2017-01-27 12:05:45 +00:00
|
|
|
// emsa2.cpp - originally written and placed in the public domain by Wei Dai
|
2015-11-05 06:59:46 +00:00
|
|
|
|
|
|
|
|
#include "pch.h"
|
|
|
|
|
#include "emsa2.h"
|
|
|
|
|
|
|
|
|
|
#ifndef CRYPTOPP_IMPORTS
|
|
|
|
|
|
|
|
|
|
NAMESPACE_BEGIN(CryptoPP)
|
|
|
|
|
|
2016-09-10 08:57:48 +00:00
|
|
|
void EMSA2Pad::ComputeMessageRepresentative(RandomNumberGenerator& /*rng*/,
|
2015-11-05 06:59:46 +00:00
|
|
|
const byte* recoverableMessage, size_t recoverableMessageLength,
|
|
|
|
|
HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
|
|
|
|
|
byte *representative, size_t representativeBitLength) const
|
|
|
|
|
{
|
|
|
|
|
CRYPTOPP_UNUSED(recoverableMessage), CRYPTOPP_UNUSED(recoverableMessageLength), CRYPTOPP_UNUSED(representativeBitLength);
|
2016-09-16 15:27:15 +00:00
|
|
|
CRYPTOPP_ASSERT(representativeBitLength >= MinRepresentativeBitLength(hashIdentifier.second, hash.DigestSize()));
|
2015-11-05 06:59:46 +00:00
|
|
|
|
|
|
|
|
if (representativeBitLength % 8 != 7)
|
|
|
|
|
throw PK_SignatureScheme::InvalidKeyLength("EMSA2: EMSA2 requires a key length that is a multiple of 8");
|
|
|
|
|
|
|
|
|
|
size_t digestSize = hash.DigestSize();
|
|
|
|
|
size_t representativeByteLength = BitsToBytes(representativeBitLength);
|
|
|
|
|
|
|
|
|
|
representative[0] = messageEmpty ? 0x4b : 0x6b;
|
|
|
|
|
memset(representative+1, 0xbb, representativeByteLength-digestSize-4); // pad with 0xbb
|
|
|
|
|
byte *afterP2 = representative+representativeByteLength-digestSize-3;
|
|
|
|
|
afterP2[0] = 0xba;
|
|
|
|
|
hash.Final(afterP2+1);
|
|
|
|
|
representative[representativeByteLength-2] = *hashIdentifier.first;
|
|
|
|
|
representative[representativeByteLength-1] = 0xcc;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
NAMESPACE_END
|
|
|
|
|
|
|
|
|
|
#endif
|
