crypto/symmetric_key.h

   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 <string>
   9
  10 #include "base/basictypes.h"
  11 #include "crypto/crypto_export.h"
  12
  13 #if defined(NACL_WIN64)
  14 // See comments for crypto_nacl_win64 in crypto.gyp.
  15 // Must test for NACL_WIN64 before OS_WIN since former is a subset of latter.
  16 #include "crypto/scoped_capi_types.h"
  17 #elif defined(USE_NSS_CERTS) || \
  18     (!defined(USE_OPENSSL) && (defined(OS_WIN) || defined(OS_MACOSX)))
  19 #include "crypto/scoped_nss_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. |key_size_in_bits| must be a multiple of 8.
  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. |key_size_in_bits| must be a
  46   // multiple of 8. The caller is responsible for deleting the returned
  47   // SymmetricKey.
  48   static SymmetricKey* DeriveKeyFromPassword(Algorithm algorithm,
  49                                              const std::string& password,
  50                                              const std::string& salt,
  51                                              size_t iterations,
  52                                              size_t key_size_in_bits);
  53
  54   // Imports an array of key bytes in |raw_key|. This key may have been
  55   // generated by GenerateRandomKey or DeriveKeyFromPassword and exported with
  56   // GetRawKey, or via another compatible method. The key must be of suitable
  57   // size for use with |algorithm|. The caller owns the returned SymmetricKey.
  58   static SymmetricKey* Import(Algorithm algorithm, const std::string& raw_key);
  59
  60 #if defined(NACL_WIN64)
  61   HCRYPTKEY key() const { return key_.get(); }
  62 #elif defined(USE_OPENSSL)
  63   const std::string& key() { return key_; }
  64 #elif defined(USE_NSS_CERTS) || defined(OS_WIN) || defined(OS_MACOSX)
  65   PK11SymKey* key() const { return key_.get(); }
  66 #endif
  67
  68   // Extracts the raw key from the platform specific data.
  69   // Warning: |raw_key| holds the raw key as bytes and thus must be handled
  70   // carefully.
  71   bool GetRawKey(std::string* raw_key);
  72
  73  private:
  74 #if defined(NACL_WIN64)
  75   SymmetricKey(HCRYPTPROV provider, HCRYPTKEY key,
  76                const void* key_data, size_t key_size_in_bytes);
  77
  78   ScopedHCRYPTPROV provider_;
  79   ScopedHCRYPTKEY key_;
  80
  81   // Contains the raw key, if it is known during initialization and when it
  82   // is likely that the associated |provider_| will be unable to export the
  83   // |key_|. This is the case of HMAC keys when the key size exceeds 16 bytes
  84   // when using the default RSA provider.
  85   // TODO(rsleevi): See if KP_EFFECTIVE_KEYLEN is the reason why CryptExportKey
  86   // fails with NTE_BAD_KEY/NTE_BAD_LEN
  87   std::string raw_key_;
  88 #elif defined(USE_OPENSSL)
  89   SymmetricKey() {}
  90   std::string key_;
  91 #elif defined(USE_NSS_CERTS) || defined(OS_WIN) || defined(OS_MACOSX)
  92   explicit SymmetricKey(PK11SymKey* key);
  93   ScopedPK11SymKey key_;
  94 #endif
  95
  96   DISALLOW_COPY_AND_ASSIGN(SymmetricKey);
  97 };
  98
  99 }  // namespace crypto
 100
 101 #endif  // CRYPTO_SYMMETRIC_KEY_H_