Make string_util::WriteInto() DCHECK() that the supplied |length_with_null| > 1, meaning that the...

crypto/symmetric_key_openssl.cc

 // Copyright (c) 2011 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 "crypto/symmetric_key.h"
 
 #include <openssl/evp.h>
 #include <openssl/rand.h>
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string_util.h"
 #include "crypto/openssl_util.h"
 
 namespace crypto {
 
 SymmetricKey::~SymmetricKey() {
   std::fill(key_.begin(), key_.end(), '\0');  // Zero out the confidential key.
 }
 
 // static
 SymmetricKey* SymmetricKey::GenerateRandomKey(Algorithm algorithm,
                                               size_t key_size_in_bits) {
   DCHECK_EQ(AES, algorithm);
-  int key_size_in_bytes = key_size_in_bits / 8;
-  DCHECK_EQ(static_cast<int>(key_size_in_bits), key_size_in_bytes * 8);
+  size_t key_size_in_bytes = key_size_in_bits / 8;
+  DCHECK_EQ(key_size_in_bits, key_size_in_bytes * 8);
 
-  if (key_size_in_bits == 0)
+  if (key_size_in_bytes == 0)
     return NULL;
 
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
   scoped_ptr<SymmetricKey> key(new SymmetricKey);
   uint8* key_data =
       reinterpret_cast<uint8*>(WriteInto(&key->key_, key_size_in_bytes + 1));
 
-  int rv = RAND_bytes(key_data, key_size_in_bytes);
+  int rv = RAND_bytes(key_data, static_cast<int>(key_size_in_bytes));
   return rv == 1 ? key.release() : NULL;
 }
 
 // static
 SymmetricKey* SymmetricKey::DeriveKeyFromPassword(Algorithm algorithm,
                                                   const std::string& password,
                                                   const std::string& salt,
                                                   size_t iterations,
                                                   size_t key_size_in_bits) {
   DCHECK(algorithm == AES || algorithm == HMAC_SHA1);
-  int key_size_in_bytes = key_size_in_bits / 8;
-  DCHECK_EQ(static_cast<int>(key_size_in_bits), key_size_in_bytes * 8);
+  size_t key_size_in_bytes = key_size_in_bits / 8;
+  DCHECK_EQ(key_size_in_bits, key_size_in_bytes * 8);
+
+  if (key_size_in_bytes == 0)
+    return NULL;
 
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
   scoped_ptr<SymmetricKey> key(new SymmetricKey);
   uint8* key_data =
       reinterpret_cast<uint8*>(WriteInto(&key->key_, key_size_in_bytes + 1));
   int rv = PKCS5_PBKDF2_HMAC_SHA1(password.data(), password.length(),
                                   reinterpret_cast<const uint8*>(salt.data()),
                                   salt.length(), iterations,
-                                  key_size_in_bytes, key_data);
+                                  static_cast<int>(key_size_in_bytes),
+                                  key_data);
   return rv == 1 ? key.release() : NULL;
 }
 
 // static
 SymmetricKey* SymmetricKey::Import(Algorithm algorithm,
                                    const std::string& raw_key) {
   scoped_ptr<SymmetricKey> key(new SymmetricKey);
   key->key_ = raw_key;
   return key.release();
 }
 
 bool SymmetricKey::GetRawKey(std::string* raw_key) {
   *raw_key = key_;
   return true;
 }
 
 }  // namespace crypto