crypto/symmetric_key_openssl.cc

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "crypto/symmetric_key.h"
   6
   7 #include <openssl/evp.h>
   8 #include <openssl/rand.h>
   9
  10 #include <algorithm>
  11
  12 #include "base/logging.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/strings/string_util.h"
  15 #include "crypto/openssl_util.h"
  16
  17 namespace crypto {
  18
  19 SymmetricKey::~SymmetricKey() {
  20   std::fill(key_.begin(), key_.end(), '\0');  // Zero out the confidential key.
  21 }
  22
  23 // static
  24 SymmetricKey* SymmetricKey::GenerateRandomKey(Algorithm algorithm,
  25                                               size_t key_size_in_bits) {
  26   DCHECK_EQ(AES, algorithm);
  27
  28   // Whitelist supported key sizes to avoid accidentaly relying on
  29   // algorithms available in NSS but not BoringSSL and vice
  30   // versa. Note that BoringSSL does not support AES-192.
  31   if (key_size_in_bits != 128 && key_size_in_bits != 256)
  32     return NULL;
  33
  34   size_t key_size_in_bytes = key_size_in_bits / 8;
  35   DCHECK_EQ(key_size_in_bits, key_size_in_bytes * 8);
  36
  37   if (key_size_in_bytes == 0)
  38     return NULL;
  39
  40   OpenSSLErrStackTracer err_tracer(FROM_HERE);
  41   scoped_ptr<SymmetricKey> key(new SymmetricKey);
  42   uint8* key_data =
  43       reinterpret_cast<uint8*>(WriteInto(&key->key_, key_size_in_bytes + 1));
  44
  45   int rv = RAND_bytes(key_data, static_cast<int>(key_size_in_bytes));
  46   return rv == 1 ? key.release() : NULL;
  47 }
  48
  49 // static
  50 SymmetricKey* SymmetricKey::DeriveKeyFromPassword(Algorithm algorithm,
  51                                                   const std::string& password,
  52                                                   const std::string& salt,
  53                                                   size_t iterations,
  54                                                   size_t key_size_in_bits) {
  55   DCHECK(algorithm == AES || algorithm == HMAC_SHA1);
  56
  57   if (algorithm == AES) {
  58     // Whitelist supported key sizes to avoid accidentaly relying on
  59     // algorithms available in NSS but not BoringSSL and vice
  60     // versa. Note that BoringSSL does not support AES-192.
  61     if (key_size_in_bits != 128 && key_size_in_bits != 256)
  62       return NULL;
  63   }
  64
  65   size_t key_size_in_bytes = key_size_in_bits / 8;
  66   DCHECK_EQ(key_size_in_bits, key_size_in_bytes * 8);
  67
  68   if (key_size_in_bytes == 0)
  69     return NULL;
  70
  71   OpenSSLErrStackTracer err_tracer(FROM_HERE);
  72   scoped_ptr<SymmetricKey> key(new SymmetricKey);
  73   uint8* key_data =
  74       reinterpret_cast<uint8*>(WriteInto(&key->key_, key_size_in_bytes + 1));
  75   int rv = PKCS5_PBKDF2_HMAC_SHA1(password.data(), password.length(),
  76                                   reinterpret_cast<const uint8*>(salt.data()),
  77                                   salt.length(), iterations,
  78                                   static_cast<int>(key_size_in_bytes),
  79                                   key_data);
  80   return rv == 1 ? key.release() : NULL;
  81 }
  82
  83 // static
  84 SymmetricKey* SymmetricKey::Import(Algorithm algorithm,
  85                                    const std::string& raw_key) {
  86   if (algorithm == AES) {
  87     // Whitelist supported key sizes to avoid accidentaly relying on
  88     // algorithms available in NSS but not BoringSSL and vice
  89     // versa. Note that BoringSSL does not support AES-192.
  90     if (raw_key.size() != 128/8 && raw_key.size() != 256/8)
  91       return NULL;
  92   }
  93
  94   scoped_ptr<SymmetricKey> key(new SymmetricKey);
  95   key->key_ = raw_key;
  96   return key.release();
  97 }
  98
  99 bool SymmetricKey::GetRawKey(std::string* raw_key) {
 100   *raw_key = key_;
 101   return true;
 102 }
 103
 104 }  // namespace crypto