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52 lines (48 loc) · 2.15 KB
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export async function sha256Hex(str) {
const buf = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(str));
return Array.from(new Uint8Array(buf)).map(b => b.toString(16).padStart(2, '0')).join('');
}
export async function keyFingerprint(key) {
return (await sha256Hex(key)).slice(0, 16);
}
export async function verifyPkceS256(codeVerifier, codeChallenge) {
// Validate code_verifier: 43-128 chars, URL-safe charset [A-Za-z0-9-._~] (RFC 7636 §4.1)
if (typeof codeVerifier !== 'string' ||
codeVerifier.length < 43 || codeVerifier.length > 128 ||
!/^[A-Za-z0-9\-._~]+$/.test(codeVerifier)) {
return null; // null = invalid_request (malformed input)
}
// Validate code_challenge: base64url-encoded SHA-256 = exactly 43 chars, no padding
if (typeof codeChallenge !== 'string' ||
codeChallenge.length !== 43 ||
!/^[A-Za-z0-9\-_]+$/.test(codeChallenge)) {
return null;
}
const hash = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(codeVerifier));
const computed = btoa(String.fromCharCode(...new Uint8Array(hash)))
.replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
const enc = new TextEncoder();
const a = enc.encode(computed), b = enc.encode(codeChallenge);
let diff = 0;
for (let i = 0; i < a.length; i++) diff |= a[i] ^ b[i];
return diff === 0; // true = match, false = wrong verifier; null = invalid_request
}
export async function timingSafeIncludes(candidate, validKeys) {
if (!candidate || !validKeys.length) return false;
const enc = new TextEncoder();
const candidateHash = await crypto.subtle.digest('SHA-256', enc.encode(candidate));
const candidateBytes = new Uint8Array(candidateHash);
let found = false;
for (const k of validKeys) {
const kHash = await crypto.subtle.digest('SHA-256', enc.encode(k));
const kBytes = new Uint8Array(kHash);
let diff = 0;
for (let i = 0; i < kBytes.length; i++) diff |= candidateBytes[i] ^ kBytes[i];
if (diff === 0) found = true;
}
return found;
}
export async function timingSafeEqualSecret(candidate, expected) {
if (!candidate || !expected) return false;
return timingSafeIncludes(candidate, [expected]);
}