1 // Copyright (c) 2012 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 #ifndef CRYPTO_SYMMETRIC_KEY_H_
6 #define CRYPTO_SYMMETRIC_KEY_H_
7 
8 #include <stddef.h>
9 
10 #include <memory>
11 #include <string>
12 
13 #include "base/macros.h"
14 #include "build/build_config.h"
15 #include "crypto/crypto_export.h"
16 
17 namespace crypto {
18 
19 // Wraps a platform-specific symmetric key and allows it to be held in a
20 // scoped_ptr.
21 class CRYPTO_EXPORT SymmetricKey {
22  public:
23   // Defines the algorithm that a key will be used with. See also
24   // classs Encrptor.
25   enum Algorithm {
26     AES,
27     HMAC_SHA1,
28   };
29 
30   virtual ~SymmetricKey();
31 
32   // Generates a random key suitable to be used with |algorithm| and of
33   // |key_size_in_bits| bits. |key_size_in_bits| must be a multiple of 8.
34   // The caller is responsible for deleting the returned SymmetricKey.
35   static std::unique_ptr<SymmetricKey> GenerateRandomKey(
36       Algorithm algorithm,
37       size_t key_size_in_bits);
38 
39   // Derives a key from the supplied password and salt using PBKDF2, suitable
40   // for use with specified |algorithm|. Note |algorithm| is not the algorithm
41   // used to derive the key from the password. |key_size_in_bits| must be a
42   // multiple of 8. The caller is responsible for deleting the returned
43   // SymmetricKey.
44   static std::unique_ptr<SymmetricKey> DeriveKeyFromPassword(
45       Algorithm algorithm,
46       const std::string& password,
47       const std::string& salt,
48       size_t iterations,
49       size_t key_size_in_bits);
50 
51   // Imports an array of key bytes in |raw_key|. This key may have been
52   // generated by GenerateRandomKey or DeriveKeyFromPassword and exported with
53   // key(). The key must be of suitable size for use with |algorithm|.
54   // The caller owns the returned SymmetricKey.
55   static std::unique_ptr<SymmetricKey> Import(Algorithm algorithm,
56                                               const std::string& raw_key);
57 
58   // Returns the raw platform specific key data.
key()59   const std::string& key() const { return key_; }
60 
61  private:
62   SymmetricKey();
63 
64   std::string key_;
65 
66   DISALLOW_COPY_AND_ASSIGN(SymmetricKey);
67 };
68 
69 }  // namespace crypto
70 
71 #endif  // CRYPTO_SYMMETRIC_KEY_H_
72