CN116170131B - Ciphertext processing method, device, storage medium and trusted execution device - Google Patents

Abstract

This application relates to the technical field of homomorphic encryption, and discloses a ciphertext processing method, device, storage medium, and trusted execution device, including: obtaining the first homomorphic encryption obtained after the first user performs homomorphic encryption on the first data; text; the first homomorphic ciphertext contains the first user's private key parameter; obtain the conversion key obtained by the first user and the second user through key agreement, and convert the first homomorphic ciphertext by using the conversion key Convert the first homomorphic ciphertext by converting the first user private key parameter into the second user private key parameter to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext contains the second user private key parameter; convert The post-homomorphic ciphertext is sent to the second user, so that the second user performs homomorphic calculation on the converted homomorphic ciphertext and the second homomorphic ciphertext obtained by performing homomorphic encryption on the second data by the second user. This application can realize homomorphic computation between homomorphic ciphertexts of different users.

Description

Ciphertext processing method, device, storage medium and trusted execution device

technical field

The invention relates to the technical field of homomorphic encryption, in particular to a ciphertext processing method, device, storage medium and trusted execution device.

Background technique

Homomorphic Encryption (HE, Homomorphic Encryption) refers to the plaintext equivalent obtained by performing a specific operation (homomorphic calculation) on the obtained ciphertext after homomorphic encryption of the original data, and then performing homomorphic decryption on the calculation result. The data result obtained by directly performing the same calculation on the original plaintext data. As an advanced method with the highest security in privacy computing technology, homomorphic encryption can encrypt data after collection, and protect and enhance data privacy security in subsequent homomorphic computing. However, the above-mentioned homomorphic computing process is realized based on the same user, that is, the same user uses the same key for homomorphic encryption, and the data encrypted by different users using different keys cannot realize direct homomorphic computing.

Therefore, how to implement homomorphic computation between homomorphic ciphertexts of different users is a technical problem to be solved urgently by those skilled in the art.

Contents of the invention

In view of this, the object of the present invention is to provide a ciphertext processing method, device, storage medium and trusted execution device, capable of realizing homomorphic computation between homomorphic ciphertexts of different users. The specific plan is as follows:

The first aspect of the present application provides a method for processing ciphertext, including:

Obtaining the first homomorphic ciphertext obtained after the first user performs homomorphic encryption on the first data; the first homomorphic ciphertext includes the first user private key parameter;

Obtain a conversion key obtained by the first user and the second user through key negotiation, and convert the first user's private key parameter in the first homomorphic ciphertext into the second Converting the first homomorphic ciphertext according to the user private key parameter to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext includes the second user private key parameter;

Sending the converted homomorphic ciphertext to the second user, so that the second user homomorphically encrypts the converted homomorphic ciphertext and the second user homomorphically encrypts the second data. Bihomomorphic ciphertext performs homomorphic computation.

Optionally, the conversion key includes the first conversion key of the first user and the second conversion key of the second user; the first conversion key is the private key parameter of the first user and the intermediate A first logical operation result of the conversion key, the second conversion key is a second logical operation result of the second user private key parameter and the intermediate conversion key.

Optionally, the intermediate conversion key is a key determined through key negotiation when the second user sends an authorization request to the first user.

Optionally, the acquiring the conversion key obtained by the first user and the second user through key agreement includes:

If the first user and the second user can determine the intermediate conversion key through key negotiation, then obtain all the intermediate conversion keys obtained by performing logical operations on the private key parameters of the first user and the intermediate conversion key. The first conversion key and the second conversion key obtained by performing logical operations on the second user private key parameter and the intermediate conversion key;

If the first user and the second user cannot determine the intermediate transformation key through key negotiation, directly obtain the first user private key parameter as the first transformation key, and directly obtain the second transformation key. The user private key parameter is used as the second conversion key.

Optionally, the intermediate conversion key is the third logical operation result of the first private key package and the second private key package; the first private key package is composed of the first user’s private key parameters and The random factor is obtained by performing a logical operation, and the second private key package is obtained by the second user performing a logical operation on the second user private key parameter and the random factor;

Correspondingly, the first conversion key is a key expression that only includes the second user private key parameter and a random factor obtained after logical operation is performed on the first user private key parameter and the third logical operation result;

The second conversion key is a key expression that only includes the first user private key parameter and a random factor, which is obtained after logical operation is performed on the second user private key parameter and the third logical operation result.

Optionally, the formula for generating the intermediate conversion key is:

tk ₁₂ =F(s ₁ , s ₂ , r ₁ , r ₂ )

Among them, F is the key generation function, the logical operation corresponding to F is addition or subtraction, s ₁ is the first user's private key parameter, s ₂ is the second user's private key parameter, r ₁ and r ₂ are random factors.

Optionally, converting the first homomorphic ciphertext by using the conversion key to convert the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter ,include:

Using the first homomorphic ciphertext, the first conversion key, and the second conversion key to construct a ciphertext conversion relationship with a private key parameter that can be eliminated;

Converting the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter based on the ciphertext conversion relational expression.

Optionally, after the acquisition of the conversion key obtained by the first user and the second user through key agreement, the method further includes:

Obtain authentication information;

According to the authentication information, it is judged whether the second user is a user authorized by the first user, and if so, performing the conversion of the first user private key in the first homomorphic ciphertext by using the conversion key. A step of converting the first homomorphic ciphertext by converting parameters into second user private key parameters.

Optionally, the authentication information is a digital signature obtained after signing the first homomorphic ciphertext with the intermediate conversion key;

The judging whether the second user is a user authorized by the first user according to the authentication information includes:

The digital signature is verified by using the intermediate conversion key, and if the verification is successful, it is determined that the second user is authorized by the first user.

Optionally, the conversion key and the authentication information are stored in a trusted execution environment in the trusted execution device;

Obtaining the conversion key and the authentication information, including:

Obtain the conversion key and the authentication information from the trusted execution environment.

Optionally, the ciphertext processing method also includes:

Build a security authentication information table in the trusted execution environment, and use the security authentication information table to store the conversion key and the authentication information; the security authentication information table also stores the first Homomorphic ciphertext and authentication methods.

Optionally, the ciphertext processing method also includes:

The trusted execution device is initialized according to the basic specification of the trusted environment, so as to build the trusted execution environment.

Optionally, the trusted execution environment is divided into a public computing area and a trusted computing area.

Optionally, the conversion key and the authentication information are stored in the trusted computing area.

Optionally, the determining whether the second user is a user authorized by the first user according to the authentication information includes:

The step of judging whether the second user is authorized by the first user according to the authentication information is performed in the trusted computing area.

Optionally, the obtaining the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data includes:

Obtaining from the first user the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data using a homomorphic encryption algorithm;

Correspondingly, the second homomorphic ciphertext is obtained by the second user after performing homomorphic encryption on the second data by using the homomorphic encryption algorithm.

Optionally, the first homomorphic ciphertext is obtained by the first user using the homomorphic encryption algorithm to homomorphically encrypt the first encoded data of the first data; the first encoded data is Encoded data conforming to a homomorphic encryption input data format obtained after the first user performs an encoding operation on the first data.

Optionally, after the second user performs homomorphic calculation on the converted homomorphic ciphertext and the second homomorphic ciphertext obtained after the second user homomorphically encrypts the second data, the method further includes:

The second user performs homomorphic decryption on the ciphertext obtained after the homomorphic calculation to obtain the decrypted plaintext.

Optionally, the second user performs homomorphic decryption on the ciphertext obtained after homomorphic calculation, and after obtaining the decrypted plaintext, further includes:

The second user performs a decoding operation on the decrypted plaintext to obtain corresponding decoded data; the decoded data is the result obtained by directly performing the same calculation as the homomorphic calculation on the first data and the second data unanimous.

The second aspect of the present application provides a trusted execution device, the trusted execution device includes a processor and a memory; wherein the memory is used to store a computer program, and the computer program is loaded and executed by the processor to Realize the foregoing ciphertext processing method.

Optionally, the processor is constructed with a trusted execution environment including a public computing area and a trusted computing area.

A third aspect of the present application provides a ciphertext processing device, including:

The ciphertext obtaining module is used to obtain the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data; the first homomorphic ciphertext includes the first user private key parameter;

The key acquisition and ciphertext conversion module is used to obtain the conversion key obtained by the first user and the second user through key agreement, and use the conversion key to convert the first homomorphic ciphertext Convert the first user private key parameter to the second user private key parameter to convert the first homomorphic ciphertext to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext contains the second user private key key parameter;

A ciphertext sending module, configured to send the converted homomorphic ciphertext to the second user, so that the second user performs the conversion on the converted homomorphic ciphertext and the second user on the second data The second homomorphic ciphertext obtained after homomorphic encryption is subjected to homomorphic calculation.

A fourth aspect of the present application provides a computer-readable storage medium, where computer-executable instructions are stored in the computer-readable storage medium, and when the computer-executable instructions are loaded and executed by a processor, the aforementioned ciphertext processing is realized method.

In this application, first obtain the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data; the first homomorphic ciphertext contains the first user's private key parameter; The conversion key obtained by the user and the second user through key agreement, and using the conversion key to convert the first user's private key parameter in the first homomorphic ciphertext into the second user's private key parameter The first homomorphic ciphertext is converted to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext contains the second user private key parameter; finally, the converted homomorphic ciphertext is sent to the a second user, so that the second user performs homomorphic computation on the converted homomorphic ciphertext and a second homomorphic ciphertext obtained by performing homomorphic encryption on second data by the second user. It can be seen that this application converts a user's homomorphic ciphertext into another user's homomorphic ciphertext through ciphertext conversion, thereby eliminating the need for data ownership users to perform complex calculations and management, and realizing different users. Homomorphic computation between homomorphic ciphertexts.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is a flow chart of a method for processing ciphertext provided by the present application;

Fig. 2 is a schematic diagram of a specific ciphertext processing method provided by the present application;

FIG. 3 is a schematic structural diagram of a ciphertext processing device provided by the present application;

FIG. 4 is a structural diagram of a trusted execution device provided by the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The homomorphic computing process in the existing homomorphic encryption technology is realized based on the same user, that is, the same user uses the same key to perform homomorphic encryption, and the data encrypted by different users using different keys cannot realize direct homomorphic computing. In view of the above-mentioned technical defects, this application provides a ciphertext processing scheme, which converts a user's homomorphic ciphertext into another user's homomorphic ciphertext that can perform homomorphic calculations by means of ciphertext conversion, thereby eliminating the need for data ownership users Execute complex calculations and management, and realize homomorphic calculations between homomorphic ciphertexts of different users.

FIG. 1 is a flow chart of a method for processing ciphertext provided in an embodiment of the present application. Referring to shown in Figure 1, the ciphertext processing method includes:

S11: Obtain a first homomorphic ciphertext obtained after the first user performs homomorphic encryption on the first data; the first homomorphic ciphertext includes a private key parameter of the first user.

In this embodiment, the first homomorphic ciphertext obtained after the first user performs homomorphic encryption on the first data is obtained first. Wherein, the first homomorphic ciphertext includes a first user private key parameter. Further, the first homomorphic ciphertext is ciphertext obtained by homomorphic encryption of the first data by the first user using a homomorphic encryption algorithm. It should be noted that, in order to improve the credibility of homomorphic computing, the above step S11 and the ciphertext processing steps in the following embodiments can be executed in a trusted execution environment, and the trusted execution environment can be executed by a trusted execution environment. Device provision, here the trusted execution device is a computing device independent of the first user and the second user, and mainly provides a trusted execution environment for trusted computing.

It can be understood that the homomorphic encryption key pair includes a private key (expressed as sk) and a public key (expressed as pk), and the key pair needs to be generated in advance. Specifically, the user public parameter p, private key can be generated for the system according to the homomorphic encryption algorithm. Key sk, public key pk, and other system public parameters para required in the subsequent stages. Randomly select the arrays S, a, and e, set the private key of the system user U as sk, and publicize the public key pk. Here, the first user is denoted as U ₁ , the private key sk ₁ of U ₁ is (1, s ₁ ), and the private key pk ₁ of U ₁ is (b, a), where b=-as ₁ +e , where s ₁ is the first user private key parameter. Similarly, the second user may be expressed as U ₂ , and other parameters are expressed in the same way. The first homomorphic ciphertext output by the first user U ₁ after performing an encryption operation on the first data (plaintext m ₁ ) according to the homomorphic encryption algorithm is:

C ₁ =v·pk ₁ + (m ₁ +e ₀ , e ₁ ) = (-vas ₁ +ve+ m ₁ +e ₀ , va+e ₁ )

Among them, v , e ₀ , e ₁ are random factors.

S12: Obtain the conversion key obtained by the first user and the second user through key negotiation, and use the conversion key to convert the first user's private key parameter in the first homomorphic ciphertext into The first homomorphic ciphertext is converted according to the parameters of the second user's private key to obtain a converted homomorphic ciphertext; the converted homomorphic ciphertext includes the second user's private key parameter.

In this embodiment, the conversion key obtained by the first user and the second user through key negotiation is further obtained, and by using the conversion key, the first user's private key in the first homomorphic ciphertext The first homomorphic ciphertext is converted by converting the key parameter into the second user private key parameter to obtain the converted homomorphic ciphertext. Under the trusted execution environment, the trusted execution device obtains the conversion key and executes the ciphertext conversion. Similarly, the converted homomorphic ciphertext contains the second user's private key parameter. Specifically, the second homomorphic ciphertext is performed by the second user using the homomorphic encryption algorithm on the second data. Obtained after homomorphic encryption. In this embodiment, the result of the ciphertext conversion is that the converted homomorphic ciphertext does not contain the first user private key parameter, but only contains the second user private key parameter, that is, the first homomorphic ciphertext in the first homomorphic ciphertext A user private key parameter is converted into a second user private key parameter. In this way, the converted homomorphic ciphertext is equivalent to the data obtained by the second user performing homomorphic encryption on the first data, so that Homomorphic calculations can be performed.

In this embodiment, the conversion key includes the first conversion key of the first user and the second conversion key of the second user; the first conversion key is the first user's private key parameter and The logical operation result of the intermediate conversion key, the second conversion key is the logical operation result of the second user private key parameter and the intermediate conversion key. Logical operations can be addition, subtraction, multiplication, division, etc., which is not limited in this embodiment, and the intermediate conversion key is expressed as tk _ij (i, j represent users), for example, the first conversion key can finally be expressed as s ₁ -tk ₁₂ . The second conversion key can finally be expressed as s ₂ -tk ₁₂ . Further, the intermediate conversion key is a key determined through key negotiation when the second user sends an authorization request to the first user, that is, the intermediate conversion key is Generated. Of course, the intermediate conversion key can also be issued by a third-party organization like a private key. In this way, the intermediate conversion key triggers the second user to send an authorization request to the first user. A key generated by a third-party institution, the above-mentioned third-party institution may be a trusted institution such as a bank.

What needs to be specially explained here is that in order to avoid potential security risks caused by private key leakage, the first user U ₁ and the second user U ₂ do not share their respective private keys when performing key negotiation to determine the intermediate conversion key , but to further generate a private key bag, and determine the intermediate conversion key by sharing the private key bag, so that direct sharing of the private key can be avoided. That is to say, the intermediate conversion key is the third logical operation result of the first private key package and the second private key package, wherein the first private key package is obtained by the first user with the first user private key parameters and random factors are obtained by logical operation, and the second private key package is obtained by the second user by logical operation of second user private key parameters and random factors. On this basis, the first conversion key is a key expression that only includes the second user private key parameters and random factors obtained after performing logical operations on the first user private key parameters and the third logical operation result; The second conversion key is a key expression that only includes the first user private key parameter and a random factor, which is obtained after logical operation is performed on the second user private key parameter and the third logical operation result. That is to say, the purpose of performing logical operations on the first user private key parameter and the third logical operation result is to eliminate the first user private key parameter, so that the first conversion key only includes the second user private key parameter and Key expression for the random factor. Similarly, the purpose of performing logical operations on the second user private key parameters and the third logical operation result is to eliminate the second user private key parameters, so that the second conversion key only includes the first user private key parameters and the random The key expression for the factor. This is the implementation basis for subsequent ciphertext conversion.

For example, when the first user U ₁ authorizes the second user U ₂ to obtain the use rights such as decryption and calculation of the ciphertext C ₁ , the two parties generate a shared intermediate conversion key tk ₁₂ through a secure form such as key negotiation, and the intermediate conversion key The generation formula of is as follows:

tk ₁₂ =F(s ₁ , s ₂ , r ₁ , r ₂ )

Among them, F is the key generation function, the logical operation corresponding to F is addition or subtraction, r ₁ and r ₂ are random factors.

When the third logical operation corresponding to F is addition:

tk ₁₂ = F(s ₁ , s ₂ , r ₁ , r ₂ ) = (s ₁ + r ₁ ) + (s ₂ + r ₂ )

Among them, s ₁ + r ₁ is the first private key package, s ₂ + r ₂ is the second private key package, and the F here makes the result of the third logic operation be the combination of s ₁ + r ₁ and s ₂ + r ₂ The result of summing.

Under this example, in order to make the first conversion key only include the second user private key parameter, the key expression of the first conversion key can only be s ₁ -tk ₁₂ . Similarly, in order to make the second conversion key only include the first user private key parameter, the key expression of the second conversion key can only be s ₂ -tk ₁₂ . This embodiment does not limit each logic operation, as long as the corresponding first conversion key and the second conversion key can be obtained. For example, when tk ₁₂ =F'(s ₁ , s ₂ , r ₁ , r ₂ )=(s ₂ + r ₂ )-(s ₁ + r ₁ ), the key expression of the first transformation key is s ₁ +tk ₁₂ , and the key expression of the second conversion key is s ₂ +tk ₁₂ .

In this embodiment, if the first user and the second user can determine the intermediate conversion key through key negotiation, then obtain The first conversion key obtained by logical operation and the second conversion key obtained by performing logical operation on the second user private key parameter and the intermediate conversion key. If the first user and the second user cannot determine the intermediate transformation key through key negotiation, directly obtain the first user private key parameter as the first transformation key, and directly obtain the second transformation key. The user private key parameter is used as the second conversion key. Under the framework of a third-party organization, if the first user and the second user can determine the intermediate conversion key through key agreement, then obtain the first conversion key from the third-party organization and the second conversion key; the first conversion key is obtained by logical operation of the first user private key parameter and the intermediate conversion key by the third party organization, and the second conversion key is obtained by the The third-party institution performs logical operations on the second user's private key parameter and the intermediate conversion key, that is, the above-mentioned method. If the first user and the second user cannot obtain the intermediate conversion key through key agreement, then obtain the first conversion key and the second conversion key from the third party organization; The third-party organization directly uses the first user private key parameter as the first conversion key and uses the second user private key parameter as the second conversion key. That is, when the participants cannot achieve secure key agreement, the other tk _ij is 0, and the participants and the trusted execution device securely share their respective private keys.

On this basis, before performing ciphertext conversion, it is necessary to use the first homomorphic ciphertext, the first conversion key and the second conversion key to construct a ciphertext with a private key parameter that can eliminate the relationship converting a relational expression, and then converting the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter based on the ciphertext conversion relational expression. The ciphertext conversion relational expression in this embodiment can be constructed as follows:

-vas ₁ +ve+m ₁ +e ₀ +(va+e)(s ₁ -tk ₁₂ )-(va+e)(s ₂ -tk ₁₂ )

After simplifying the calculation of the above ciphertext conversion relational expression, the relational expression is:

-vas ₂ +ve+ m ₁ +e ₀ +es ₁ +es ₂

Considering e _s = e ₀ + es ₁ +es ₂ as a noise interference item (negligible), the final transformation is as follows:

-vas ₂ +ve+ m ₁ +e _s

Finally, replace -vas ₁ +ve+m ₊ e ₀ in C ₁ with -vas ₂ +ve+m+e s to obtain the converted homomorphic ciphertext.

What needs to be explained here is that for the authorized user group U _J (J={j,j+1,...,j+n-1}, n is the number of users in the authorized user group), decryption, calculation, etc. use permissions, the transform key generation function expands to:

tk ₁₂ =F(s _i , s _j , s _j+1 ,...,s _j+n-1 , r _j , r _j+1 ,...,r _j+n-1 )

For authorized user groups in this embodiment, a conversion method between homomorphic ciphertexts encrypted with different keys can be designed based on a trusted execution environment, and a shared conversion key can be generated during the data authorization and use phase, and the key can be Securely stored in the trusted execution device, the conversion key can convert all homomorphic ciphertexts of the same version/security level into homomorphic ones that can be decrypted/calculated by authorized user groups in the trusted execution environment of the trusted execution device Ciphertext, which greatly reduces the calculation and management burden of data ownership users, and at the same time improves the user-friendliness and practicality of data sharing, analysis and use.

S13: Send the converted homomorphic ciphertext to the second user, so that the second user performs homomorphic encryption on the converted homomorphic ciphertext and the second user performs homomorphic encryption on second data to obtain The second homomorphic ciphertext performs homomorphic computation.

In this embodiment, after the ciphertext conversion, the converted homomorphic ciphertext can be sent to the second user, so that the second user can compare the converted homomorphic ciphertext with the first The second user performs homomorphic computation on the second homomorphic ciphertext obtained after performing homomorphic encryption on the second data.

It can be seen that in the embodiment of the present application, the first homomorphic ciphertext obtained after the first user performs homomorphic encryption on the first data is firstly obtained; the first homomorphic ciphertext contains the private key parameters of the first user; The conversion key obtained by the first user and the second user through key negotiation, and using the conversion key to convert the first user's private key parameter in the first homomorphic ciphertext into the second user's private key The first homomorphic ciphertext is converted by means of parameters to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext contains the second user private key parameter; finally, the converted homomorphic ciphertext is sent to the second user, so that the second user performs homomorphic computation on the converted homomorphic ciphertext and a second homomorphic ciphertext obtained after the second user performs homomorphic encryption on second data. In this embodiment of the present application, one user's homomorphic ciphertext is converted into another user's homomorphic ciphertext that can perform homomorphic calculations, so that the data ownership user is not required to perform complex calculations and management, and the homomorphic ciphertext of different users is realized. homomorphic calculation.

FIG. 2 is a flow chart of a specific ciphertext processing method provided by the embodiment of the present application. Referring to shown in Figure 2, the ciphertext processing method includes:

S21: Acquire from the first user the first homomorphic ciphertext obtained by the first user using a homomorphic encryption algorithm to homomorphically encrypt the first data; the first homomorphic ciphertext includes the first user's private key parameter .

In this embodiment, regarding the specific process of the above step S21, reference may be made to the corresponding content disclosed in the foregoing embodiments, and details are not repeated here. What needs to be added here is that before performing homomorphic encryption, the first user also needs to perform an encoding operation on the first data, so that the obtained first encoded data conforms to the input data format of homomorphic encryption. That is, the first homomorphic ciphertext is obtained by the first user using the homomorphic encryption algorithm to homomorphically encrypt the first coded data of the first data; the first coded data is the first Encoded data conforming to the input data format of homomorphic encryption obtained by a user after performing an encoding operation on the first data. That is, according to the homomorphic encryption algorithm, the data of the system user U is encoded into plaintext that meets the encryption input requirements.

S22: Obtain the conversion key and authentication information obtained by the first user and the second user through key agreement from the trusted execution environment in the trusted execution device.

In this embodiment, the conversion key and authentication information obtained by the first user and the second user through key agreement need to be obtained from the trusted execution environment in the trusted execution device. The trusted execution environment is to construct a security area in the processor of the trusted execution device through software and hardware methods, so as to ensure that the programs and data loaded inside are protected in terms of confidentiality and integrity. Specifically, the trusted execution device can be initialized according to the basic specification of the trusted environment to build the trusted execution environment, and the conversion key and the authentication information are stored in the trusted execution device Trusted Execution Environment. Further, the trusted execution environment is divided into a public computing area and a trusted computing area, and the conversion key and the authentication information are stored in the trusted computing area.

That is, initialize the trusted execution device according to the basic specification of the trusted environment, set up the public computing area and the trusted computing area, securely store the conversion key in the storage device of the trusted computing area, and initialize the conversion key and ciphertext at the same time , authentication information (signature/version/security level, etc.), etc. In this embodiment, a security authentication information table can also be constructed in the trusted execution environment, and the conversion key and the authentication information can be stored by using the security authentication information table. In addition, the security authentication information The table also stores the first homomorphic ciphertext and the authentication method. The following table is an example of a security authentication information table:

S23: Determine whether the second user is a user authorized by the first user according to the authentication information, and if so, use the conversion key to encrypt the first user in the first homomorphic ciphertext The first homomorphic ciphertext is converted by converting the key parameter into the second user private key parameter to obtain the converted homomorphic ciphertext.

In this embodiment, after the conversion key and authentication information are obtained, it is judged according to the authentication information whether the second user is authorized by the first user, and if so, by using the conversion key The first homomorphic ciphertext is converted by converting the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter to obtain a converted homomorphic ciphertext. Wherein, the step of judging whether the second user is authorized by the first user according to the authentication information is performed in the trusted computing area. That is to say, the authenticity of the message is authenticated by the trusted execution environment through the message authentication function. If the verification is passed, the trusted execution environment reads the conversion key, and then the trusted execution environment converts the first user's ciphertext into the second The user's ciphertext.

In this embodiment, the authentication information may be a digital signature obtained by signing the first homomorphic ciphertext with the intermediate conversion key, and the authentication method at this time is signature (as shown in the above table). When performing verification, the digital signature is verified by using the intermediate conversion key, and if the verification is successful, it is determined that the second user is authorized by the first user. After the trusted execution device receives the ciphertext conversion request from the authorized user, it first queries the security authentication information table in the trusted execution environment. If the authentication information (signature) is verified, it executes the ciphertext conversion, otherwise it exits.

S24: Send the converted homomorphic ciphertext to the second user, so that the second user performs homomorphic encryption on the converted homomorphic ciphertext and the second user performs homomorphic encryption on second data to obtain The second homomorphic ciphertext is subjected to homomorphic calculation, and the ciphertext obtained after the homomorphic calculation is subjected to homomorphic decryption to obtain the decrypted plaintext.

In this embodiment, regarding the specific process of the above step S24, reference may be made to the corresponding content disclosed in the foregoing embodiments, and details are not repeated here. It should be added that after obtaining the decrypted plaintext, it is also necessary to perform a decoding operation on the decrypted plaintext to obtain corresponding decoded data; the decoded data is directly related to the first data and the second data. Performing the same computation as a homomorphic computation yields the same result.

Referring to Figure 3, the embodiment of the present application also discloses a ciphertext processing device correspondingly, including:

The ciphertext obtaining module 11 is used to obtain the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data; the first homomorphic ciphertext includes the first user private key parameter;

A key acquisition and ciphertext conversion module 12, configured to obtain a conversion key obtained by the first user and the second user through key agreement, and convert the first homomorphic encryption In the article, the first user private key parameter is converted into the second user private key parameter to convert the first homomorphic ciphertext to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext includes the second user private key parameter;

The ciphertext sending module 13 is configured to send the converted homomorphic ciphertext to the second user, so that the second user can understand the converted homomorphic ciphertext and the second user can understand the second data The second homomorphic ciphertext obtained after homomorphic encryption is subjected to homomorphic calculation.

It can be seen that in the embodiment of the present application, the first homomorphic ciphertext obtained after the first user performs homomorphic encryption on the first data is firstly obtained; the first homomorphic ciphertext contains the private key parameters of the first user; The conversion key obtained by the first user and the second user through key negotiation, and using the conversion key to convert the first user's private key parameter in the first homomorphic ciphertext into the second user's private key The first homomorphic ciphertext is converted by means of parameters to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext contains the second user private key parameter; finally, the converted homomorphic ciphertext is sent to the second user, so that the second user performs homomorphic computation on the converted homomorphic ciphertext and a second homomorphic ciphertext obtained after the second user performs homomorphic encryption on second data. In this embodiment of the present application, the homomorphic ciphertext of one user is converted into the homomorphic ciphertext that another user can perform homomorphic calculations by means of ciphertext conversion, thereby eliminating the need for data ownership users to perform complex calculations and management, and realizing the ciphertext of different users. Homomorphic computation between homomorphic ciphertexts.

In some specific embodiments, the ciphertext processing device also includes:

An authentication information acquisition module, configured to acquire authentication information;

An authentication module, configured to judge whether the second user is a user authorized by the first user according to the authentication information, and if yes, convert the first homomorphic ciphertext by using the conversion key A step of converting the first homomorphic ciphertext by converting the first user private key parameter into the second user private key parameter.

In some specific embodiments, the conversion key in the ciphertext processing device includes a first conversion key of the first user and a second conversion key of the second user; the first conversion The key is the first logical operation result of the first user private key parameter and the intermediate conversion key, and the second conversion key is the second logical operation result of the second user private key parameter and the intermediate conversion key.

In some specific embodiments, the intermediate conversion key in the ciphertext processing apparatus is a key determined through key agreement when the second user sends an authorization request to the first user.

In some specific embodiments, the ciphertext acquisition module 11 specifically includes:

The first obtaining unit is configured to obtain the intermediate conversion key by comparing the private key parameter of the first user with the intermediate conversion key if the first user and the second user can determine the intermediate conversion key through key negotiation. The first conversion key obtained by performing a logical operation on the key and the second conversion key obtained by performing a logical operation on the second user private key parameter and the intermediate conversion key;

The second acquiring unit is configured to directly acquire the private key parameter of the first user as the first conversion key if the first user and the second user cannot determine the intermediate conversion key through key negotiation. key, and directly obtain the second user private key parameter as the second conversion key.

In some specific embodiments, the intermediate conversion key in the ciphertext processing device is the third logical operation result of the first private key package and the second private key package; the first private key package is obtained by the The first user obtains the logical operation of the first user private key parameter and the random factor, and the second private key package is obtained by the second user through the logical operation of the second user private key parameter and the random factor;

Correspondingly, the first conversion key is a key expression that only includes the second user private key parameter and a random factor obtained after logical operation is performed on the first user private key parameter and the third logical operation result;

The second conversion key is a key expression that only includes the first user private key parameter and a random factor, which is obtained after logical operation is performed on the second user private key parameter and the third logical operation result.

In some specific embodiments, the generation formula of the intermediate conversion key in the ciphertext processing device is:

tk ₁₂ =F(s ₁ , s ₂ , r ₁ , r ₂ )

Among them, F is the key generation function, the logical operation corresponding to F is addition or subtraction, s ₁ is the first user's private key parameter, s ₂ is the second user's private key parameter, r ₁ and r ₂ are random factors.

In some specific embodiments, the key acquisition and ciphertext conversion module 12 specifically further includes:

A relational expression construction submodule, configured to use the first homomorphic ciphertext, the first conversion key, and the second conversion key to construct a ciphertext conversion relational expression with a private key parameter that can eliminate the relationship;

A conversion submodule, configured to convert the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter based on the ciphertext conversion relational expression.

In some specific embodiments, the authentication information is a digital signature obtained after signing the first homomorphic ciphertext with the intermediate transformation key;

The authentication module is specifically configured to use the intermediate conversion key to verify the digital signature, and if the verification passes, determine that the second user is authorized by the first user.

In some specific embodiments, the conversion key and the authentication information in the ciphertext processing apparatus are stored in a trusted execution environment in the trusted execution device.

In some specific embodiments, the ciphertext processing device further includes:

A table construction module, configured to construct a security authentication information table in the trusted execution environment, and use the security authentication information table to store the conversion key and the authentication information; the security authentication information table also contains The first homomorphic ciphertext and the authentication method are stored;

The initialization module is configured to initialize the trusted execution device according to the basic specification of the trusted environment, so as to build the trusted execution environment.

In some specific embodiments, the trusted execution environment in the ciphertext processing device is divided into a public computing area and a trusted computing area, and the conversion key and the authentication information are stored in the trusted computing area .

In some specific embodiments, the authentication module is specifically configured to perform the step of judging whether the second user is a user authorized by the first user according to the authentication information in the trusted computing area.

In some specific embodiments, the ciphertext acquisition module 11 is also used for:

Obtaining from the first user the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data using a homomorphic encryption algorithm;

Correspondingly, the second homomorphic ciphertext is obtained by the second user using the homomorphic encryption algorithm to homomorphically encrypt the second data;

The first homomorphic ciphertext is obtained by the first user using the homomorphic encryption algorithm to homomorphically encrypt the first encoded data of the first data; the first encoded data is the first Encoded data conforming to the input data format of homomorphic encryption obtained after the user performs an encoding operation on the first data.

In some specific embodiments, the ciphertext processing device also includes:

The decryption module is used for the second user to perform homomorphic decryption on the ciphertext obtained after the homomorphic calculation to obtain the decrypted plaintext;

The decoding module is used for the second user to perform a decoding operation on the decrypted plaintext to obtain corresponding decoded data, and the decoded data is the same as directly performing homomorphic calculation on the first data and the second data The calculated results are consistent.

Furthermore, the embodiment of the present application also provides a trusted execution device. Fig. 4 is a structural diagram of an electronic device 20 according to an exemplary embodiment, and the content in the diagram should not be regarded as any limitation on the application scope of the present application.

FIG. 4 is a schematic structural diagram of a trusted execution device 20 provided in an embodiment of the present application. The trusted execution device 20 may specifically include: at least one processor 21 , at least one memory 22 , a power supply 23 , a communication interface 24 , an input/output interface 25 and a communication bus 26 . Wherein, the memory 22 is used to store a computer program, and the computer program is loaded and executed by the processor 21 to at least realize the following steps:

Obtaining the first homomorphic ciphertext obtained after the first user performs homomorphic encryption on the first data; the first homomorphic ciphertext includes the first user private key parameter;

Obtain a conversion key obtained by the first user and the second user through key negotiation, and convert the first user's private key parameter in the first homomorphic ciphertext into the second Converting the first homomorphic ciphertext according to the user private key parameter to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext includes the second user private key parameter;

Sending the converted homomorphic ciphertext to the second user, so that the second user homomorphically encrypts the converted homomorphic ciphertext and the second user homomorphically encrypts the second data. Bihomomorphic ciphertext performs homomorphic computation.

It can be seen that the trusted execution device in the embodiment of the present application first obtains the first homomorphic ciphertext obtained after the first user performs homomorphic encryption on the first data; the first homomorphic ciphertext contains the first user's private key parameter; then obtain the conversion key obtained by the first user and the second user through key negotiation, and use the conversion key to parameterize the first user's private key in the first homomorphic ciphertext The first homomorphic ciphertext is converted into the second user private key parameter to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext contains the second user private key parameter; and finally the The converted homomorphic ciphertext is sent to the second user, so that the second user performs homomorphic encryption on the converted homomorphic ciphertext and the second user performs homomorphic encryption on the second data. The ciphertext is homomorphically computed. The embodiment of this application integrates the trusted execution technology and the homomorphic encryption technology, and the trusted execution device converts a user's homomorphic ciphertext into another user's homomorphic calculation in a secure environment through ciphertext conversion. The homomorphic ciphertext of different users does not need data ownership users to perform complex calculations and management, and realizes homomorphic calculation between homomorphic ciphertexts of different users.

Optionally, the conversion key includes the first conversion key of the first user and the second conversion key of the second user; the first conversion key is the private key parameter of the first user and the intermediate A first logical operation result of the conversion key, the second conversion key is a second logical operation result of the second user private key parameter and the intermediate conversion key.

Optionally, the intermediate conversion key is a key determined through key negotiation when the second user sends an authorization request to the first user.

Optionally, the acquiring the conversion key obtained by the first user and the second user through key agreement includes:

If the first user and the second user can determine the intermediate conversion key through key negotiation, then obtain all the intermediate conversion keys obtained by performing logical operations on the private key parameters of the first user and the intermediate conversion key. The first conversion key and the second conversion key obtained by performing logical operations on the second user private key parameter and the intermediate conversion key;

If the first user and the second user cannot determine the intermediate transformation key through key negotiation, directly obtain the first user private key parameter as the first transformation key, and directly obtain the second transformation key. The user private key parameter is used as the second conversion key.

Optionally, the intermediate conversion key is the third logical operation result of the first private key package and the second private key package; the first private key package is composed of the first user’s private key parameters and The random factor is obtained by performing a logical operation, and the second private key package is obtained by the second user performing a logical operation on the second user private key parameter and the random factor;

Correspondingly, the first conversion key is a key expression that only includes the second user private key parameter and a random factor obtained after logical operation is performed on the first user private key parameter and the third logical operation result;

The second conversion key is a key expression that only includes the first user private key parameter and a random factor, which is obtained after logical operation is performed on the second user private key parameter and the third logical operation result.

Optionally, the formula for generating the intermediate conversion key is:

tk ₁₂ =F(s ₁ , s ₂ , r ₁ , r ₂ )

Among them, F is the key generation function, the logical operation corresponding to F is addition or subtraction, s ₁ is the first user's private key parameter, s ₂ is the second user's private key parameter, r ₁ and r ₂ are random factors.

Optionally, converting the first homomorphic ciphertext by using the conversion key to convert the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter ,include:

Using the first homomorphic ciphertext, the first conversion key, and the second conversion key to construct a ciphertext conversion relationship with a private key parameter that can be eliminated;

Converting the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter based on the ciphertext conversion relational expression.

Optionally, after the acquisition of the conversion key obtained by the first user and the second user through key agreement, the method further includes:

Obtain authentication information;

According to the authentication information, it is judged whether the second user is a user authorized by the first user, and if so, performing the conversion of the first user private key in the first homomorphic ciphertext by using the conversion key. A step of converting the first homomorphic ciphertext by converting parameters into second user private key parameters.

Optionally, the authentication information is a digital signature obtained after signing the first homomorphic ciphertext with the intermediate conversion key;

The judging whether the second user is a user authorized by the first user according to the authentication information includes:

The digital signature is verified by using the intermediate conversion key, and if the verification is successful, it is determined that the second user is authorized by the first user.

Optionally, the conversion key and the authentication information are stored in a trusted execution environment in the trusted execution device;

Obtaining the conversion key and the authentication information, including:

Obtain the conversion key and the authentication information from the trusted execution environment.

Optionally, the ciphertext processing method also includes:

Build a security authentication information table in the trusted execution environment, and use the security authentication information table to store the conversion key and the authentication information; the security authentication information table also stores the first Homomorphic ciphertext and authentication methods.

Optionally, the ciphertext processing method also includes:

The trusted execution device is initialized according to the basic specification of the trusted environment, so as to build the trusted execution environment.

Optionally, the trusted execution environment is divided into a public computing area and a trusted computing area.

Optionally, the conversion key and the authentication information are stored in the trusted computing area.

Optionally, the determining whether the second user is a user authorized by the first user according to the authentication information includes:

The step of judging whether the second user is authorized by the first user according to the authentication information is performed in the trusted computing area.

Optionally, the obtaining the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data includes:

Obtaining from the first user the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data using a homomorphic encryption algorithm;

Correspondingly, the second homomorphic ciphertext is obtained by the second user after performing homomorphic encryption on the second data by using the homomorphic encryption algorithm.

Optionally, the first homomorphic ciphertext is obtained by the first user using the homomorphic encryption algorithm to homomorphically encrypt the first encoded data of the first data; the first encoded data is Encoded data conforming to a homomorphic encryption input data format obtained after the first user performs an encoding operation on the first data.

Optionally, after the second user performs homomorphic calculation on the converted homomorphic ciphertext and the second homomorphic ciphertext obtained after the second user homomorphically encrypts the second data, the method further includes:

The second user performs homomorphic decryption on the ciphertext obtained after the homomorphic calculation to obtain the decrypted plaintext.

Optionally, the second user performs homomorphic decryption on the ciphertext obtained after homomorphic calculation, and after obtaining the decrypted plaintext, further includes:

The second user performs a decoding operation on the decrypted plaintext to obtain corresponding decoded data; the decoded data is the result obtained by directly performing the same calculation as the homomorphic calculation on the first data and the second data unanimous.

In this embodiment, the power supply 23 is used to provide operating voltage for each hardware device on the trusted execution device 20; the communication interface 24 can create a data transmission channel between the trusted execution device 20 and external devices, and the communication it follows The protocol is any communication protocol that can be applied to the technical solution of this application, and it is not specifically limited here; the input and output interface 25 is used to obtain external input data or output data to the external, and its specific interface type can be configured according to specific application needs. selection, and is not specifically limited here.

In addition, the memory 22, as a resource storage carrier, can be a read-only memory, random access memory, magnetic disk or optical disk, etc., and the resources stored thereon can include the operating system 221, computer programs 222 and data 223, etc., and the storage method can be short-term storage or permanent storage.

Among them, the operating system 221 is used to manage and control each hardware device and computer program 222 on the trusted execution device 20, so as to realize the calculation and processing of the massive data 223 in the memory 22 by the processor 21, which can be WindowsServer, Netware, Unix , Linux, etc. In addition to computer programs that can be used to complete the ciphertext processing methods performed by the trusted execution device 20 disclosed in any of the foregoing embodiments, the computer program 222 may further include computer programs that can be used to complete other specific tasks. The data 223 may include the first homomorphic ciphertext collected by the electronic device 20 .

Further, the embodiment of the present application also discloses a storage medium, in which a computer program is stored, and when the computer program is loaded and executed by a processor, at least the following steps are implemented:

Obtaining the first homomorphic ciphertext obtained after the first user performs homomorphic encryption on the first data; the first homomorphic ciphertext includes the first user private key parameter;

Obtain a conversion key obtained by the first user and the second user through key negotiation, and convert the first user's private key parameter in the first homomorphic ciphertext into the second Converting the first homomorphic ciphertext according to the user private key parameter to obtain the converted homomorphic ciphertext; the converted homomorphic ciphertext includes the second user private key parameter;

Sending the converted homomorphic ciphertext to the second user, so that the second user homomorphically encrypts the converted homomorphic ciphertext and the second user homomorphically encrypts the second data. Bihomomorphic ciphertext performs homomorphic computation.

Optionally, the conversion key includes the first conversion key of the first user and the second conversion key of the second user; the first conversion key is the private key parameter of the first user and the intermediate A first logical operation result of the conversion key, the second conversion key is a second logical operation result of the second user private key parameter and the intermediate conversion key.

Optionally, the intermediate conversion key is a key determined through key negotiation when the second user sends an authorization request to the first user.

Optionally, the acquiring the conversion key obtained by the first user and the second user through key agreement includes:

If the first user and the second user can determine the intermediate conversion key through key negotiation, then obtain all the intermediate conversion keys obtained by performing logical operations on the private key parameters of the first user and the intermediate conversion key. The first conversion key and the second conversion key obtained by performing logical operations on the second user private key parameter and the intermediate conversion key;

If the first user and the second user cannot determine the intermediate transformation key through key negotiation, directly obtain the first user private key parameter as the first transformation key, and directly obtain the second transformation key. The user private key parameter is used as the second conversion key.

Optionally, the intermediate conversion key is the third logical operation result of the first private key package and the second private key package; the first private key package is composed of the first user’s private key parameters and The random factor is obtained by performing a logical operation, and the second private key package is obtained by the second user performing a logical operation on the second user private key parameter and the random factor;

Correspondingly, the first conversion key is a key expression that only includes the second user private key parameter and a random factor obtained after logical operation is performed on the first user private key parameter and the third logical operation result;

The second conversion key is a key expression that only includes the first user private key parameter and a random factor, which is obtained after logical operation is performed on the second user private key parameter and the third logical operation result.

Optionally, the formula for generating the intermediate conversion key is:

tk ₁₂ =F(s ₁ , s ₂ , r ₁ , r ₂ )

Among them, F is the key generation function, the logical operation corresponding to F is addition or subtraction, s ₁ is the first user's private key parameter, s ₂ is the second user's private key parameter, r ₁ and r ₂ are random factors.

Optionally, converting the first homomorphic ciphertext by using the conversion key to convert the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter ,include:

Using the first homomorphic ciphertext, the first conversion key, and the second conversion key to construct a ciphertext conversion relationship with a private key parameter that can be eliminated;

Converting the first user private key parameter in the first homomorphic ciphertext into a second user private key parameter based on the ciphertext conversion relational expression.

Optionally, after the acquisition of the conversion key obtained by the first user and the second user through key agreement, the method further includes:

Obtain authentication information;

According to the authentication information, it is judged whether the second user is a user authorized by the first user, and if so, performing the conversion of the first user private key in the first homomorphic ciphertext by using the conversion key. A step of converting the first homomorphic ciphertext by converting parameters into second user private key parameters.

Optionally, the authentication information is a digital signature obtained after signing the first homomorphic ciphertext with the intermediate conversion key;

The judging whether the second user is a user authorized by the first user according to the authentication information includes:

The digital signature is verified by using the intermediate conversion key, and if the verification is successful, it is determined that the second user is authorized by the first user.

Optionally, the conversion key and the authentication information are stored in a trusted execution environment in the trusted execution device;

Obtaining the conversion key and the authentication information, including:

Obtain the conversion key and the authentication information from the trusted execution environment.

Optionally, the ciphertext processing method also includes:

Build a security authentication information table in the trusted execution environment, and use the security authentication information table to store the conversion key and the authentication information; the security authentication information table also stores the first Homomorphic ciphertext and authentication methods.

Optionally, the ciphertext processing method also includes:

The trusted execution device is initialized according to the basic specification of the trusted environment, so as to build the trusted execution environment.

Optionally, the trusted execution environment is divided into a public computing area and a trusted computing area.

Optionally, the conversion key and the authentication information are stored in the trusted computing area.

Optionally, the determining whether the second user is a user authorized by the first user according to the authentication information includes:

The step of judging whether the second user is authorized by the first user according to the authentication information is performed in the trusted computing area.

Optionally, the obtaining the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data includes:

Obtaining from the first user the first homomorphic ciphertext obtained after the first user homomorphically encrypts the first data using a homomorphic encryption algorithm;

Correspondingly, the second homomorphic ciphertext is obtained by the second user after performing homomorphic encryption on the second data by using the homomorphic encryption algorithm.

Optionally, the first homomorphic ciphertext is obtained by the first user using the homomorphic encryption algorithm to homomorphically encrypt the first encoded data of the first data; the first encoded data is Encoded data conforming to a homomorphic encryption input data format obtained after the first user performs an encoding operation on the first data.

Optionally, after the second user performs homomorphic calculation on the converted homomorphic ciphertext and the second homomorphic ciphertext obtained after the second user homomorphically encrypts the second data, the method further includes:

The second user performs homomorphic decryption on the ciphertext obtained after the homomorphic calculation to obtain the decrypted plaintext.

Optionally, the second user performs homomorphic decryption on the ciphertext obtained after homomorphic calculation, and after obtaining the decrypted plaintext, further includes:

The second user performs a decoding operation on the decrypted plaintext to obtain corresponding decoded data; the decoded data is the result obtained by directly performing the same calculation as the homomorphic calculation on the first data and the second data unanimous.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same or similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for relevant details, please refer to the description of the method part.

Finally, it should also be noted that in this text, relational terms such as first and second etc. are only used to distinguish one entity or operation from another, and do not necessarily require or imply that these entities or operations, any such actual relationship or order exists. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

The ciphertext processing method, device, storage medium and trusted execution device provided by the present invention have been introduced in detail above. In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used To help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary, this specification The content should not be construed as a limitation of the invention.

Claims (21)

1. A ciphertext processing method, comprising:

acquiring a first homomorphic ciphertext obtained after homomorphic encryption of first data by a first user; the first homomorphic ciphertext comprises a first user private key parameter;

obtaining a conversion key obtained by the first user and the second user through a key negotiation mode, and converting the first homomorphic ciphertext through a mode of converting a first user private key parameter in the first homomorphic ciphertext into a second user private key parameter by using the conversion key to obtain a converted homomorphic ciphertext; the homomorphic ciphertext after conversion comprises a second user private key parameter;

Sending the converted homomorphic ciphertext to the second user, so that the second user carries out homomorphic calculation on the converted homomorphic ciphertext and a second homomorphic ciphertext obtained after the second user carries out homomorphic encryption on second data;

the obtaining the conversion key obtained by the first user and the second user through a key negotiation mode comprises the following steps: if the first user and the second user can determine the intermediate conversion key through a key negotiation mode, a first conversion key obtained by carrying out logic operation on a first user private key parameter and the intermediate conversion key and a second conversion key obtained by carrying out logic operation on a second user private key parameter and the intermediate conversion key are obtained; if the first user and the second user cannot determine the intermediate conversion key in a key negotiation mode, directly acquiring a first user private key parameter as a first conversion key, and directly acquiring a second user private key parameter as a second conversion key;

the converting the first homomorphic ciphertext by converting the first user private key parameter in the first homomorphic ciphertext into the second user private key parameter by using the conversion key includes: constructing a ciphertext conversion relation with a private key parameter elimination relation by using the first homomorphic ciphertext, the first conversion key and the second conversion key; and converting the first user private key parameter in the first homomorphic secret into a second user private key parameter based on the ciphertext conversion relation.

2. The ciphertext processing method of claim 1, wherein the conversion key comprises a first conversion key of the first user and a second conversion key of the second user; the first conversion key is a first logical operation result of the first user private key parameter and the intermediate conversion key, and the second conversion key is a second logical operation result of the second user private key parameter and the intermediate conversion key.

3. The ciphertext processing method of claim 2, wherein the intermediate conversion key is a key determined by a key agreement manner when the second user sends an authorization request to the first user.

4. The ciphertext processing method of claim 2 wherein the intermediate conversion key is a third logical operation result of the first private key package and the second private key package; the first private key package is obtained by carrying out logic operation on a first user private key parameter and a random factor by the first user, and the second private key package is obtained by carrying out logic operation on a second user private key parameter and the random factor by the second user;

correspondingly, the first conversion key is a key expression which is obtained by carrying out logic operation on the first user private key parameter and the third logic operation result and only comprises the second user private key parameter and the random factor;

The second conversion key is a key expression which is obtained by carrying out logic operation on the second user private key parameter and the third logic operation result and only comprises the first user private key parameter and the random factor.

5. The ciphertext processing method of claim 4, wherein the intermediate conversion key has a generation formula of:

tk ₁₂ =F（s ₁ ，s ₂ ，r ₁ ，r ₂ ）

wherein F is a key generation function, the logical operation corresponding to F is addition or subtraction, s ₁ S is a first user private key parameter ₂ R is the second user private key parameter ₁ And r ₂ Is a random factor.

6. The ciphertext processing method of claim 2, wherein after the obtaining the conversion key obtained by the first user and the second user by the key negotiation method, further comprises:

acquiring authentication information;

judging whether the second user is the user authorized by the first user according to the authentication information, and if so, executing the step of converting the first homomorphic ciphertext in a mode of converting the first user private key parameter in the first homomorphic ciphertext into the second user private key parameter by utilizing the conversion key.

7. The ciphertext processing method of claim 6, wherein the authentication information is a digital signature obtained by signing the first homomorphic ciphertext with the intermediate conversion key;

The step of judging whether the second user is a user authorized by the first user according to the authentication information comprises the following steps:

and verifying the digital signature by using the intermediate conversion key, and if the verification passes, judging that the second user is the user authorized by the first user.

8. The ciphertext processing method of claim 6, wherein the conversion key and the authentication information are stored in a trusted execution environment in a trusted execution device;

obtaining the conversion key and the authentication information includes:

the conversion key and the authentication information are acquired from the trusted execution environment.

9. The ciphertext processing method of claim 8, further comprising:

constructing a security authentication information table in the trusted execution environment, and storing the conversion key and the authentication information by utilizing the security authentication information table; the security authentication information table also stores the first homomorphic ciphertext and an authentication mode.

10. The ciphertext processing method of claim 8, further comprising:

and initializing the trusted execution device according to the trusted environment basic specification to construct the trusted execution environment.

11. The ciphertext processing method of claim 8, wherein the trusted execution environment is divided into a common computing area and a trusted computing area.

12. The ciphertext processing method of claim 11, wherein the conversion key and the authentication information are stored in the trusted computing zone.

13. The ciphertext processing method of claim 9, wherein the determining whether the second user is a user authorized by the first user based on the authentication information comprises:

the step of determining whether the second user is a user authorized by the first user based on the authentication information is performed in a trusted computing area.

14. The ciphertext processing method according to any one of claims 1 to 13, wherein the obtaining a first homomorphic ciphertext obtained by homomorphically encrypting first data by a first user comprises:

acquiring the first homomorphic ciphertext obtained by the first user after homomorphic encryption of the first data by using a homomorphic encryption algorithm from the first user;

correspondingly, the second homomorphic ciphertext is obtained by homomorphic encryption of the second data by the second user through the homomorphic encryption algorithm.

15. The ciphertext processing method of claim 14 wherein the first homomorphic ciphertext is obtained by the first user homomorphic encrypting first encoded data of the first data using the homomorphic encryption algorithm; the first coded data is coded data which is obtained after the first user executes coding operation on the first data and accords with homomorphic encryption input data format.

16. The ciphertext processing method according to any one of claims 1 to 13, wherein after the second user homomorphic calculating the converted homomorphic ciphertext and a second homomorphic ciphertext obtained by homomorphic encrypting second data by the second user, further comprising:

and the second user homomorphic decrypts the ciphertext obtained after homomorphic calculation to obtain a decrypted plaintext.

17. The ciphertext processing method of claim 16, wherein the second user homomorphically decrypting the homomorphically calculated ciphertext to obtain decrypted plaintext, further comprising:

the second user executes decoding operation on the decrypted plaintext to obtain corresponding decoded data; the decoded data is consistent with the result of directly performing the same calculation as the homomorphic calculation on the first data and the second data.

18. A trusted execution device, the trusted execution device comprising a processor and a memory; wherein the memory is for storing a computer program that is loaded and executed by the processor to implement the ciphertext processing method of any one of claims 1 to 17.

19. The trusted execution device of claim 18, wherein the processor builds a trusted execution environment comprising a common computing area and a trusted computing area.

20. A ciphertext processing apparatus, comprising:

the ciphertext acquisition module is used for acquiring a first homomorphic ciphertext obtained after homomorphic encryption of the first data by the first user; the first homomorphic ciphertext comprises a first user private key parameter;

the key acquisition and ciphertext conversion module is used for acquiring a conversion key obtained by the first user and the second user in a key negotiation mode, and converting the first homomorphic ciphertext in a mode of converting a first user private key parameter in the first homomorphic ciphertext into a second user private key parameter by utilizing the conversion key to obtain a converted homomorphic ciphertext; the homomorphic ciphertext after conversion comprises a second user private key parameter;

The ciphertext sending module is used for sending the converted homomorphic ciphertext to the second user so that the second user can homomorphic calculate the converted homomorphic ciphertext and the second homomorphic ciphertext obtained by homomorphic encryption of the second data by the second user;

the key acquisition and ciphertext conversion module specifically further comprises: the first obtaining unit is used for obtaining a first conversion key obtained by carrying out logic operation on a first user private key parameter and the intermediate conversion key and a second conversion key obtained by carrying out logic operation on a second user private key parameter and the intermediate conversion key if the first user and the second user can determine the intermediate conversion key through a key negotiation mode; the second obtaining unit is used for directly obtaining a first user private key parameter as a first conversion key and directly obtaining a second user private key parameter as a second conversion key if the first user and the second user cannot determine the intermediate conversion key in a key negotiation mode; the key acquisition and ciphertext conversion module specifically further comprises: the relation construction submodule is used for constructing a ciphertext conversion relation with a private key parameter elimination relation by utilizing the first homomorphic ciphertext, the first conversion key and the second conversion key; and the conversion sub-module is used for converting the first user private key parameter in the first homomorphic secret into the second user private key parameter based on the ciphertext conversion relation.

21. A computer readable storage medium storing computer executable instructions which when loaded and executed by a processor implement the ciphertext processing method of any one of claims 1 to 17.

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