1// hmac.h - written and placed in the public domain by Wei Dai
2
3#ifndef CRYPTOPP_HMAC_H
4#define CRYPTOPP_HMAC_H
5
6#include "seckey.h"
7#include "secblock.h"
8
9NAMESPACE_BEGIN(CryptoPP)
10
11//! _
12class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE HMAC_Base : public VariableKeyLength<16, 0, INT_MAX>, public MessageAuthenticationCode
13{
14public:
15	HMAC_Base() : m_innerHashKeyed(false) {}
16	void UncheckedSetKey(const byte *userKey, unsigned int keylength, const NameValuePairs &params);
17
18	void Restart();
19	void Update(const byte *input, size_t length);
20	void TruncatedFinal(byte *mac, size_t size);
21	unsigned int OptimalBlockSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().OptimalBlockSize();}
22	unsigned int DigestSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().DigestSize();}
23
24protected:
25	virtual HashTransformation & AccessHash() =0;
26	byte * AccessIpad() {return m_buf;}
27	byte * AccessOpad() {return m_buf + AccessHash().BlockSize();}
28	byte * AccessInnerHash() {return m_buf + 2*AccessHash().BlockSize();}
29
30private:
31	void KeyInnerHash();
32
33	SecByteBlock m_buf;
34	bool m_innerHashKeyed;
35};
36
37//! <a href="http://www.weidai.com/scan-mirror/mac.html#HMAC">HMAC</a>
38/*! HMAC(K, text) = H(K XOR opad, H(K XOR ipad, text)) */
39template <class T>
40class HMAC : public MessageAuthenticationCodeImpl<HMAC_Base, HMAC<T> >
41{
42public:
43	CRYPTOPP_CONSTANT(DIGESTSIZE=T::DIGESTSIZE)
44	CRYPTOPP_CONSTANT(BLOCKSIZE=T::BLOCKSIZE)
45
46	HMAC() {}
47	HMAC(const byte *key, size_t length=HMAC_Base::DEFAULT_KEYLENGTH)
48		{this->SetKey(key, length);}
49
50	static std::string StaticAlgorithmName() {return std::string("HMAC(") + T::StaticAlgorithmName() + ")";}
51	std::string AlgorithmName() const {return std::string("HMAC(") + m_hash.AlgorithmName() + ")";}
52
53private:
54	HashTransformation & AccessHash() {return m_hash;}
55
56	T m_hash;
57};
58
59NAMESPACE_END
60
61#endif
62