Crypto++  8.2
Free C++ class library of cryptographic schemes
hmac.h
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1 // hmac.h - originally written and placed in the public domain by Wei Dai
2 
3 /// \file hmac.h
4 /// \brief Classes for HMAC message authentication codes
5 
6 #ifndef CRYPTOPP_HMAC_H
7 #define CRYPTOPP_HMAC_H
8 
9 #include "seckey.h"
10 #include "secblock.h"
11 
12 NAMESPACE_BEGIN(CryptoPP)
13 
14 /// \brief HMAC information
15 /// \details HMAC_Base derives from VariableKeyLength and MessageAuthenticationCode
16 /// \since Crypto++ 2.1
17 class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE HMAC_Base : public VariableKeyLength<16, 0, INT_MAX>, public MessageAuthenticationCode
18 {
19 public:
20  virtual ~HMAC_Base() {}
21 
22  /// \brief Construct a HMAC_Base
23  HMAC_Base() : m_innerHashKeyed(false) {}
24  void UncheckedSetKey(const byte *userKey, unsigned int keylength, const NameValuePairs &params);
25 
26  void Restart();
27  void Update(const byte *input, size_t length);
28  void TruncatedFinal(byte *mac, size_t size);
29  unsigned int OptimalBlockSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().OptimalBlockSize();}
30  unsigned int DigestSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().DigestSize();}
31 
32 protected:
33  virtual HashTransformation & AccessHash() =0;
34  byte * AccessIpad() {return m_buf;}
35  byte * AccessOpad() {return m_buf + AccessHash().BlockSize();}
36  byte * AccessInnerHash() {return m_buf + 2*AccessHash().BlockSize();}
37 
38 private:
39  void KeyInnerHash();
40 
41  SecByteBlock m_buf;
42  bool m_innerHashKeyed;
43 };
44 
45 /// \brief HMAC
46 /// \tparam T HashTransformation derived class
47 /// \details HMAC derives from MessageAuthenticationCodeImpl. It calculates the HMAC using
48 /// <tt>HMAC(K, text) = H(K XOR opad, H(K XOR ipad, text))</tt>.
49 /// \sa <a href="http://www.weidai.com/scan-mirror/mac.html#HMAC">HMAC</a>
50 /// \since Crypto++ 2.1
51 template <class T>
52 class HMAC : public MessageAuthenticationCodeImpl<HMAC_Base, HMAC<T> >
53 {
54 public:
55  CRYPTOPP_CONSTANT(DIGESTSIZE=T::DIGESTSIZE);
56  CRYPTOPP_CONSTANT(BLOCKSIZE=T::BLOCKSIZE);
57 
58  virtual ~HMAC() {}
59 
60  /// \brief Construct a HMAC
61  HMAC() {}
62  /// \brief Construct a HMAC
63  /// \param key the HMAC key
64  /// \param length the size of the HMAC key
65  HMAC(const byte *key, size_t length=HMAC_Base::DEFAULT_KEYLENGTH)
66  {this->SetKey(key, length);}
67 
68  static std::string StaticAlgorithmName() {return std::string("HMAC(") + T::StaticAlgorithmName() + ")";}
69  std::string AlgorithmName() const {return std::string("HMAC(") + m_hash.AlgorithmName() + ")";}
70  std::string AlgorithmProvider() const {return m_hash.AlgorithmProvider();}
71 
72 private:
73  HashTransformation & AccessHash() {return m_hash;}
74 
75  T m_hash;
76 };
77 
78 NAMESPACE_END
79 
80 #endif
virtual unsigned int BlockSize() const
Provides the block size of the compression function.
Definition: cryptlib.h:1165
Interface for message authentication codes.
Definition: cryptlib.h:1294
HMAC_Base()
Construct a HMAC_Base.
Definition: hmac.h:23
virtual void SetKey(const byte *key, size_t length, const NameValuePairs &params=g_nullNameValuePairs)
Sets or reset the key of this object.
Definition: cryptlib.cpp:58
HMAC()
Construct a HMAC.
Definition: hmac.h:61
unsigned int DigestSize() const
Provides the digest size of the hash.
Definition: hmac.h:30
SecBlock<byte> typedef.
Definition: secblock.h:1091
Classes and functions for secure memory allocations.
HMAC information.
Definition: hmac.h:17
Classes and functions for implementing secret key algorithms.
static const int DEFAULT_KEYLENGTH
The default key length used by the algorithm provided as a constant.
Definition: seckey.h:184
HMAC(const byte *key, size_t length=HMAC_Base::DEFAULT_KEYLENGTH)
Construct a HMAC.
Definition: hmac.h:65
Provides a base implementation of Algorithm and SimpleKeyingInterface for message authentication code...
Definition: seckey.h:362
std::string AlgorithmName() const
Provides the name of this algorithm.
Definition: hmac.h:69
unsigned int OptimalBlockSize() const
Provides the input block size most efficient for this hash.
Definition: hmac.h:29
Inherited by keyed algorithms with variable key length.
Definition: seckey.h:165
HMAC.
Definition: hmac.h:52
Interface for hash functions and data processing part of MACs.
Definition: cryptlib.h:1112
std::string AlgorithmProvider() const
Retrieve the provider of this algorithm.
Definition: hmac.h:70
Crypto++ library namespace.
Interface for retrieving values given their names.
Definition: cryptlib.h:321