fix: encrypt GitHub tokens at rest and implement secure token rotation

lib/github-token-encryption.js

@@ -0,0 +1,179 @@
+/**
+ * lib/github-token-encryption.js
+ *
+ * Secure GitHub token storage and retrieval.
+ * Prevents exposure of GitHub Personal Access Tokens (PATs) from env file leaks.
+ * Tokens are encrypted before being used or cached.
+ */
+
+import { randomBytes, createCipheriv, createDecipheriv } from 'crypto';
+
+/**
+ * Encrypt GitHub token for storage.
+ * @param {string} token - GitHub PAT or token
+ * @returns {string} Encrypted token in hex format
+ */
+export function encryptGitHubToken(token) {
+  if (!token || typeof token !== 'string') {
+    throw new Error('Invalid GitHub token');
+  }
+
+  try {
+    const key = process.env.GITHUB_TOKEN_ENCRYPTION_KEY;
+
+    if (!key) {
+      console.warn(
+        'GITHUB_TOKEN_ENCRYPTION_KEY not configured. ' +
+          'GitHub tokens should be encrypted in production.'
+      );
+      return token; // Return plaintext if encryption not configured (dev only)
+    }
+
+    const keyBuffer = Buffer.from(key, 'base64');
+    if (keyBuffer.length !== 32) {
+      throw new Error('Encryption key must be 32 bytes');
+    }
+
+    const iv = randomBytes(16);
+    const cipher = createCipheriv('aes-256-cbc', keyBuffer, iv);
+
+    let encrypted = cipher.update(token, 'utf8', 'hex');
+    encrypted += cipher.final('hex');
+
+    // Combine IV + encrypted token
+    return iv.toString('hex') + ':' + encrypted;
+  } catch (error) {
+    throw new Error(`Token encryption failed: ${error.message}`);
+  }
+}
+
+/**
+ * Decrypt GitHub token for use.
+ * @param {string} encryptedToken - Encrypted token in hex format
+ * @returns {string} Decrypted GitHub token
+ */
+export function decryptGitHubToken(encryptedToken) {
+  try {
+    const key = process.env.GITHUB_TOKEN_ENCRYPTION_KEY;
+
+    // If encryption not configured, return as-is (dev fallback)
+    if (!key) {
+      return encryptedToken;
+    }
+
+    const keyBuffer = Buffer.from(key, 'base64');
+
+    const [ivHex, encryptedHex] = encryptedToken.split(':');
+    if (!ivHex || !encryptedHex) {
+      throw new Error('Invalid encrypted token format');
+    }
+
+    const iv = Buffer.from(ivHex, 'hex');
+    const decipher = createDecipheriv('aes-256-cbc', keyBuffer, iv);
+
+    let decrypted = decipher.update(encryptedHex, 'hex', 'utf8');
+    decrypted += decipher.final('utf8');
+
+    return decrypted;
+  } catch (error) {
+    throw new Error(`Token decryption failed: ${error.message}`);
+  }
+}
+
+/**
+ * Parse comma-separated tokens and return encrypted array.
+ * Handles legacy comma-separated format and encrypts each token.
+ * @param {string} tokenString - Comma-separated tokens or single token
+ * @returns {Array<Object>} Array of {token: string, encryptedToken: string}
+ */
+export function parseAndEncryptTokens(tokenString) {
+  if (!tokenString || typeof tokenString !== 'string') {
+    throw new Error('Token string is required');
+  }
+
+  const tokens = tokenString
+    .split(',')
+    .map((t) => t.trim())
+    .filter((t) => t.length > 0);
+
+  if (tokens.length === 0) {
+    throw new Error('No valid tokens found');
+  }
+
+  // Validate token format (should start with ghp_ or ghu_)
+  for (const token of tokens) {
+    if (!token.startsWith('ghp_') && !token.startsWith('ghu_')) {
+      console.warn(`Token does not appear to be valid GitHub PAT: ${token.substring(0, 5)}...`);
+    }
+  }
+
+  // Encrypt each token
+  return tokens.map((token) => ({
+    token, // Keep plaintext temporarily for return value
+    encryptedToken: encryptGitHubToken(token),
+    rotationIndex: tokens.indexOf(token),
+  }));
+}
+
+/**
+ * Get next GitHub token from encrypted rotation list.
+ * Used to rotate tokens and distribute rate limits.
+ * @param {Array<string>} encryptedTokens - Array of encrypted tokens
+ * @param {number} currentIndex - Current rotation index
+ * @returns {Object} {token: string, nextIndex: number}
+ */
+export function getNextToken(encryptedTokens, currentIndex = 0) {
+  if (!Array.isArray(encryptedTokens) || encryptedTokens.length === 0) {
+    throw new Error('No encrypted tokens available');
+  }
+
+  const nextIndex = (currentIndex + 1) % encryptedTokens.length;
+  const encryptedToken = encryptedTokens[nextIndex];
+
+  return {
+    token: decryptGitHubToken(encryptedToken),
+    nextIndex,
+  };
+}
+
+/**
+ * Validate that a token is properly encrypted.
+ * @param {string} encryptedToken - Token to validate
+ * @returns {boolean} True if token appears to be encrypted
+ */
+export function isEncryptedToken(encryptedToken) {
+  if (!encryptedToken || typeof encryptedToken !== 'string') {
+    return false;
+  }
+
+  // Encrypted tokens have format: hex:hex
+  const parts = encryptedToken.split(':');
+  if (parts.length !== 2) {
+    return false;
+  }
+
+  // Both parts should be valid hex
+  for (const part of parts) {
+    if (!/^[a-f0-9]+$/i.test(part)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+/**
+ * CRITICAL: Never log or expose full GitHub tokens.
+ * Logging utility that safely redacts tokens.
+ * @param {string} token - Token to redact for logging
+ * @returns {string} Redacted token for safe logging
+ */
+export function redactToken(token) {
+  if (!token || token.length < 10) {
+    return '***';
+  }
+
+  const start = token.substring(0, 4);
+  const end = token.substring(token.length - 4);
+  return `${start}...${end}`;
+}