Be strict about input in the GCMMessageCryptographer

components/gcm_driver/crypto/gcm_message_cryptographer.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/gcm_driver/crypto/gcm_message_cryptographer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 167 matching lines @@
     const base::StringPiece& recipient_public_key,
     const base::StringPiece& sender_public_key,
     const base::StringPiece& ecdh_shared_secret,
     const base::StringPiece& auth_secret,
     const base::StringPiece& salt,
     const base::StringPiece& plaintext,
     size_t* record_size,
     std::string* ciphertext) const {
   DCHECK_EQ(recipient_public_key.size(), 65u);
   DCHECK_EQ(sender_public_key.size(), 65u);
+  DCHECK_EQ(ecdh_shared_secret.size(), 32u);
+  DCHECK_EQ(auth_secret.size(), 16u);
+  DCHECK_EQ(salt.size(), 16u);
   DCHECK(record_size);
   DCHECK(ciphertext);
 
-  // TODO(peter): DCHECK the lengths of |ecdh_shared_secret|, |auth_secret| and
-  // |salt|.
-
-  if (salt.size() != kSaltSize)
-    return false;
-
   std::string prk = encryption_scheme_->DerivePseudoRandomKey(
       ecdh_shared_secret, auth_secret);
 
   std::string content_encryption_key = DeriveContentEncryptionKey(
       recipient_public_key, sender_public_key, prk, salt);
   std::string nonce =
       DeriveNonce(recipient_public_key, sender_public_key, prk, salt);
 
   std::string record = encryption_scheme_->CreateRecord(plaintext);
   std::string encrypted_record;
@@ skipping 15 matching lines @@
     const base::StringPiece& recipient_public_key,
     const base::StringPiece& sender_public_key,
     const base::StringPiece& ecdh_shared_secret,
     const base::StringPiece& auth_secret,
     const base::StringPiece& salt,
     const base::StringPiece& ciphertext,
     size_t record_size,
     std::string* plaintext) const {
   DCHECK_EQ(recipient_public_key.size(), 65u);
   DCHECK_EQ(sender_public_key.size(), 65u);
+  DCHECK_EQ(ecdh_shared_secret.size(), 32u);
+  DCHECK_EQ(auth_secret.size(), 16u);
+  DCHECK_EQ(salt.size(), 16u);
   DCHECK(plaintext);
 
-  // TODO(peter): DCHECK the lengths of |ecdh_shared_secret|, |auth_secret| and
-  // |salt|.
-
   if (record_size <= 1)
     return false;
 
   std::string prk = encryption_scheme_->DerivePseudoRandomKey(
       ecdh_shared_secret, auth_secret);
 
   std::string content_encryption_key = DeriveContentEncryptionKey(
       recipient_public_key, sender_public_key, prk, salt);
 
   std::string nonce =
@@ skipping 109 matching lines @@
 
   // https://tools.ietf.org/html/draft-ietf-httpbis-encryption-encoding-02
   // defines that the result should be XOR'ed with the record's sequence number,
   // however, Web Push encryption is limited to a single record per
   // https://tools.ietf.org/html/draft-ietf-webpush-encryption-03.
 
   return hkdf.client_write_key().as_string();
 }
 
 }  // namespace gcm