support new key derivations, add new preferred versions using such

[squeep-mystery-box] / lib / mystery-box.js

diff --git a/lib/mystery-box.js b/lib/mystery-box.js
index 2343c5e164f79f9d04629a97c366a1fbd0f58595..05fe28f72c872ac80b0604af4d15bbe8f52e069f 100644 (file)
--- a/lib/mystery-box.js
+++ b/lib/mystery-box.js
@@ -63,23 +63,27 @@ class MysteryBox {
   /**
    * @param {Console} logger
    * @param {Object} options
-   * @param {String} options.encryptionSecret
+   * @param {String|String[]} options.encryptionSecret - if an array, will always encrypt with first secret, will attempt to decrypt with all; useful for rolling secrets
    * @param {Number=} options.defaultFlags
    */
   constructor(logger, options = {}) {
     this.logger = logger;
     this.options = options;
 
-    this.secret = options.encryptionSecret;
-    if (!this.secret) {
+    this.secrets = common.ensureArray(options.encryptionSecret);
+    if (!this.secrets.length) {
       throw new Error('missing encryption secret');
     }
-    // TODO: support secret rolling
 
     // Filter any unavailable algorithms
     const availableCiphers = crypto.getCiphers();
+    const availableHashes = crypto.getHashes();
+    // Add legacy scrypt to available hashes for filtering key derivations
+    availableHashes.push('scrypt');
     this.versionParameters = Object.entries(allVersions).reduce((acc, [v, p]) => {
-      if (availableCiphers.includes(p.algorithm)) {
+      const validCipher = availableCiphers.includes(p.algorithm);
+      const validKeyDeriver = availableHashes.includes(p.keyDeriver);
+      if (validCipher && validKeyDeriver) {
         acc[v] = p; // eslint-disable-line security/detect-object-injection
       }
       return acc;
@@ -110,6 +114,38 @@ class MysteryBox {
   }
 
 
+  /**
+   * Generate key data.
+   */
+  static async _keyFromSecret(deriver, secret, salt, keyBytes) {
+    switch (deriver) {
+      case 'shake256': {
+        const hash = crypto.createHash('shake256', { outputLength: keyBytes });
+        hash.update(salt);
+        hash.update(secret);
+        return hash.digest();
+      }
+
+      case 'blake2b512': {
+        const hash = crypto.createHash('blake2b512');
+        hash.update(salt);
+        hash.update(secret);
+        const digest = hash.digest();
+        // should assert that keyBytes <= 64
+        // but not concerned about that for now
+        // until we have a new algorithm with bigger key size
+        return digest.subarray(0, keyBytes);
+      }
+
+      case 'scrypt':
+        return scryptAsync(secret, salt, keyBytes);
+
+      default:
+        throw new RangeError('unsupported key deriver');
+    }
+  }
+
+
   /**
    * Put contents into a mysterious box.
    * @param {Object|Buffer} contents
@@ -176,7 +212,9 @@ class MysteryBox {
     // Authenticate all this data
     const aadBuffer = Buffer.concat([versionBuffer, flagsBuffer, iv, salt]);
 
-    const key = await scryptAsync(this.secret, salt, v.keyBytes);
+    // Always encrypt with first secret
+    const secret = this.secrets[0];
+    const key = await MysteryBox._keyFromSecret(v.keyDeriver, secret, salt, v.keyBytes);
     const cipher = crypto.createCipheriv(v.algorithm, key, iv, v.algOptions);
     cipher.setAAD(aadBuffer);
     const encrypted = cipher.update(payload);
@@ -216,7 +254,7 @@ class MysteryBox {
     const raw = Buffer.from(base64URLToBase64(box), 'base64');
     let offset = 0;
 
-    const version = raw.slice(offset, 1).readUInt8(0);
+    const version = raw.subarray(offset, 1).readUInt8(0);
     if (!(version in this.versionParameters)) {
       throw new RangeError('unsupported version');
     }
@@ -229,31 +267,47 @@ class MysteryBox {
       throw new RangeError('not enough to unpack');
     }
 
-    const flags = raw.slice(offset, offset + v.flagsBytes).readUInt8(0);
+    const flags = raw.subarray(offset, offset + v.flagsBytes).readUInt8(0);
     offset += v.flagsBytes;
 
     const { compression, payloadIsBuffer } = MysteryBox._decodeFlags(flags);
 
-    const iv = raw.slice(offset, offset + v.ivBytes);
+    const iv = raw.subarray(offset, offset + v.ivBytes);
     offset += v.ivBytes;
 
-    const salt = raw.slice(offset, offset + v.saltBytes);
+    const salt = raw.subarray(offset, offset + v.saltBytes);
     offset += v.saltBytes;
 
-    const aad = raw.slice(0, offset); // Everything up to here
+    const aad = raw.subarray(0, offset); // Everything up to here
 
-    const tag = raw.slice(offset, offset + v.tagBytes);
+    const tag = raw.subarray(offset, offset + v.tagBytes);
     offset += v.tagBytes;
 
-    const encrypted = raw.slice(offset);
+    const encrypted = raw.subarray(offset);
 
     timingsMs.preCrypt = performance.now();
-    const key = await scryptAsync(this.secret, salt, v.keyBytes);
-    const decipher = crypto.createDecipheriv(v.algorithm, key, iv, v.algOptions);
-    decipher.setAAD(aad);
-    decipher.setAuthTag(tag);
 
-    const decrypted = Buffer.concat([decipher.update(encrypted), decipher.final()]);
+    let decrypted;
+    let err;
+    let success = false;
+    for await (const secret of this.secrets) {
+      const key = await MysteryBox._keyFromSecret(v.keyDeriver, secret, salt, v.keyBytes);
+      const decipher = crypto.createDecipheriv(v.algorithm, key, iv, v.algOptions);
+      decipher.setAAD(aad);
+      decipher.setAuthTag(tag);
+
+      try {
+        decrypted = Buffer.concat([decipher.update(encrypted), decipher.final()]);
+        success = true;
+        break;
+      } catch (e) {
+        err = e;
+        continue;
+      }
+    }
+    if (!success) {
+      throw err;
+    }
 
     let payload;
     timingsMs.preCompress = timingsMs.postCrypt = performance.now();