@vfarcic/dot-ai/dist/interfaces/oauth/jwt.js

AI-powered development productivity platform that enhances software development workflows through intelligent automation and AI-driven assistance

"use strict";
/**
 * JWT signing and verification using node:crypto HMAC-SHA256.
 *
 * No external libraries — implements the minimal JWT subset needed
 * for dot-ai access tokens (HS256 only).
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.getJwtSecret = getJwtSecret;
exports._resetCachedSecret = _resetCachedSecret;
exports.signJwt = signJwt;
exports.verifyJwt = verifyJwt;
const node_crypto_1 = require("node:crypto");
const JWT_HEADER = Buffer.from(JSON.stringify({ alg: 'HS256', typ: 'JWT' })).toString('base64url');
/** Cached auto-generated secret (per-process). */
let cachedSecret;
/**
 * Returns the JWT signing secret.
 * Uses DOT_AI_JWT_SECRET env var if set, otherwise generates
 * a random 32-byte hex secret cached for the process lifetime.
 */
function getJwtSecret() {
    const envSecret = process.env.DOT_AI_JWT_SECRET;
    if (envSecret) {
        return envSecret;
    }
    if (!cachedSecret) {
        cachedSecret = (0, node_crypto_1.randomBytes)(32).toString('hex');
    }
    return cachedSecret;
}
/**
 * Reset the cached secret. Only for testing.
 * @internal
 */
function _resetCachedSecret() {
    cachedSecret = undefined;
}
/**
 * Sign a JWT with HMAC-SHA256.
 *
 * @param claims - The JWT payload claims
 * @param secret - The signing secret
 * @returns Encoded JWT string (header.payload.signature)
 */
function signJwt(claims, secret) {
    const payload = Buffer.from(JSON.stringify(claims)).toString('base64url');
    const data = `${JWT_HEADER}.${payload}`;
    const signature = (0, node_crypto_1.createHmac)('sha256', secret)
        .update(data)
        .digest('base64url');
    return `${data}.${signature}`;
}
/**
 * Verify a JWT signed with HMAC-SHA256.
 *
 * Performs timing-safe signature comparison and expiry check.
 *
 * @param token - The JWT string to verify
 * @param secret - The signing secret
 * @returns Decoded claims if valid, null otherwise
 */
function verifyJwt(token, secret) {
    const parts = token.split('.');
    if (parts.length !== 3) {
        return null;
    }
    const [header, payload, signature] = parts;
    // Recompute expected signature
    const data = `${header}.${payload}`;
    const expectedSignature = (0, node_crypto_1.createHmac)('sha256', secret)
        .update(data)
        .digest('base64url');
    // Timing-safe comparison
    const sigBuffer = Buffer.from(signature, 'base64url');
    const expectedBuffer = Buffer.from(expectedSignature, 'base64url');
    if (sigBuffer.length !== expectedBuffer.length) {
        // Dummy comparison to maintain constant time
        (0, node_crypto_1.timingSafeEqual)(expectedBuffer, expectedBuffer);
        return null;
    }
    if (!(0, node_crypto_1.timingSafeEqual)(sigBuffer, expectedBuffer)) {
        return null;
    }
    // Decode and validate claims
    let claims;
    try {
        claims = JSON.parse(Buffer.from(payload, 'base64url').toString('utf8'));
    }
    catch {
        return null;
    }
    // Validate identity claims
    if (typeof claims.sub !== 'string' || claims.sub.length === 0) {
        return null;
    }
    if (claims.groups !== undefined && !Array.isArray(claims.groups)) {
        return null;
    }
    // Check expiration (strict: exp === now is treated as expired)
    const now = Math.floor(Date.now() / 1000);
    if (typeof claims.exp !== 'number' || claims.exp <= now) {
        return null;
    }
    return claims;
}