emsa2.h

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// emsa2.h - originally written and placed in the public domain by Wei Dai
 
 
#ifndef CRYPTOPP_EMSA2_H
#define CRYPTOPP_EMSA2_H
 
#include "cryptlib.h"
#include "pubkey.h"
#include "hashfwd.h"
#include "misc.h"
 
#ifdef CRYPTOPP_IS_DLL
# include "sha.h"
#endif
 
NAMESPACE_BEGIN(CryptoPP)
 
 
template <class H> class EMSA2HashId
{
public:
        static const byte id;
};
 
template <class BASE>
class EMSA2HashIdLookup : public BASE
{
public:
        struct HashIdentifierLookup
        {
                template <class H> struct HashIdentifierLookup2
                {
                        static HashIdentifier Lookup()
                        {
                                return HashIdentifier(&EMSA2HashId<H>::id, 1);
                        }
                };
        };
};
 
// EMSA2HashId can be instantiated with the following classes.
// SHA1, SHA224, SHA256, SHA384, SHA512, RIPEMD128, RIPEMD160, Whirlpool
 
#ifdef CRYPTOPP_IS_DLL
CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA1>;
CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA224>;
CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA256>;
CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA384>;
CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA512>;
#endif
 
// https://github.com/weidai11/cryptopp/issues/300 and
// https://github.com/weidai11/cryptopp/issues/533
#if defined(__clang__)
template<> const byte EMSA2HashId<SHA1>::id;
template<> const byte EMSA2HashId<SHA224>::id;
template<> const byte EMSA2HashId<SHA256>::id;
template<> const byte EMSA2HashId<SHA384>::id;
template<> const byte EMSA2HashId<SHA512>::id;
#endif
 
class CRYPTOPP_DLL EMSA2Pad : public EMSA2HashIdLookup<PK_DeterministicSignatureMessageEncodingMethod>
{
public:
        CRYPTOPP_STATIC_CONSTEXPR const char* CRYPTOPP_API StaticAlgorithmName() {return "EMSA2";}
 
        size_t MinRepresentativeBitLength(size_t hashIdentifierLength, size_t digestLength) const
                {CRYPTOPP_UNUSED(hashIdentifierLength); return 8*digestLength + 31;}
 
        void ComputeMessageRepresentative(RandomNumberGenerator &rng,
                const byte *recoverableMessage, size_t recoverableMessageLength,
                HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
                byte *representative, size_t representativeBitLength) const;
};
 
// EMSA2, for use with RWSS and RSA_ISO
// Only the following hash functions are supported by this signature standard:
//  \dontinclude emsa2.h
//  \skip EMSA2HashId can be instantiated
//  \until end of list
 
struct P1363_EMSA2 : public SignatureStandard
{
        typedef EMSA2Pad SignatureMessageEncodingMethod;
};
 
NAMESPACE_END
 
#endif