crypto/symmetric_key.h

   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 #ifndef CRYPTO_SYMMETRIC_KEY_H_
   6 #define CRYPTO_SYMMETRIC_KEY_H_
   7 #pragma once
   8
   9 #include <string>
  10
  11 #include "base/basictypes.h"
  12 #include "crypto/crypto_export.h"
  13
  14 #if defined(USE_NSS)
  15 #include "crypto/scoped_nss_types.h"
  16 #elif defined(OS_MACOSX)
  17 #include <Security/cssmtype.h>
  18 #elif defined(OS_WIN)
  19 #include "crypto/scoped_capi_types.h"
  20 #endif
  21
  22 namespace crypto {
  23
  24 // Wraps a platform-specific symmetric key and allows it to be held in a
  25 // scoped_ptr.
  26 class CRYPTO_EXPORT SymmetricKey {
  27  public:
  28   // Defines the algorithm that a key will be used with. See also
  29   // classs Encrptor.
  30   enum Algorithm {
  31     AES,
  32     HMAC_SHA1,
  33   };
  34
  35   virtual ~SymmetricKey();
  36
  37   // Generates a random key suitable to be used with |algorithm| and of
  38   // |key_size_in_bits| bits.
  39   // The caller is responsible for deleting the returned SymmetricKey.
  40   static SymmetricKey* GenerateRandomKey(Algorithm algorithm,
  41                                          size_t key_size_in_bits);
  42
  43   // Derives a key from the supplied password and salt using PBKDF2, suitable
  44   // for use with specified |algorithm|. Note |algorithm| is not the algorithm
  45   // used to derive the key from the password. The caller is responsible for
  46   // deleting the returned SymmetricKey.
  47   static SymmetricKey* DeriveKeyFromPassword(Algorithm algorithm,
  48                                              const std::string& password,
  49                                              const std::string& salt,
  50                                              size_t iterations,
  51                                              size_t key_size_in_bits);
  52
  53   // Imports an array of key bytes in |raw_key|. This key may have been
  54   // generated by GenerateRandomKey or DeriveKeyFromPassword and exported with
  55   // GetRawKey, or via another compatible method. The key must be of suitable
  56   // size for use with |algorithm|. The caller owns the returned SymmetricKey.
  57   static SymmetricKey* Import(Algorithm algorithm, const std::string& raw_key);
  58
  59 #if defined(USE_OPENSSL)
  60   const std::string& key() { return key_; }
  61 #elif defined(USE_NSS)
  62   PK11SymKey* key() const { return key_.get(); }
  63 #elif defined(OS_MACOSX)
  64   CSSM_DATA cssm_data() const;
  65 #elif defined(OS_WIN)
  66   HCRYPTKEY key() const { return key_.get(); }
  67 #endif
  68
  69   // Extracts the raw key from the platform specific data.
  70   // Warning: |raw_key| holds the raw key as bytes and thus must be handled
  71   // carefully.
  72   bool GetRawKey(std::string* raw_key);
  73
  74  private:
  75 #if defined(USE_OPENSSL)
  76   SymmetricKey() {}
  77   std::string key_;
  78 #elif defined(USE_NSS)
  79   explicit SymmetricKey(PK11SymKey* key);
  80   ScopedPK11SymKey key_;
  81 #elif defined(OS_MACOSX)
  82   SymmetricKey(const void* key_data, size_t key_size_in_bits);
  83   std::string key_;
  84 #elif defined(OS_WIN)
  85   SymmetricKey(HCRYPTPROV provider, HCRYPTKEY key,
  86                const void* key_data, size_t key_size_in_bytes);
  87
  88   ScopedHCRYPTPROV provider_;
  89   ScopedHCRYPTKEY key_;
  90
  91   // Contains the raw key, if it is known during initialization and when it
  92   // is likely that the associated |provider_| will be unable to export the
  93   // |key_|. This is the case of HMAC keys when the key size exceeds 16 bytes
  94   // when using the default RSA provider.
  95   // TODO(rsleevi): See if KP_EFFECTIVE_KEYLEN is the reason why CryptExportKey
  96   // fails with NTE_BAD_KEY/NTE_BAD_LEN
  97   std::string raw_key_;
  98 #endif
  99
 100   DISALLOW_COPY_AND_ASSIGN(SymmetricKey);
 101 };
 102
 103 }  // namespace crypto
 104
 105 #endif  // CRYPTO_SYMMETRIC_KEY_H_