Glenn Maynard
46 lines
1.5 KiB
C++
46 lines
1.5 KiB
C++
// pkcspad.cpp - written and placed in the public domain by Wei Dai
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#include "global.h"
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#include "pch.h"
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#include "pkcspad.h"
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#include <assert.h>
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namespace CryptoPP {
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template<> const byte PKCS_DigestDecoration<SHA>::decoration[] = {0x30,0x21,0x30,0x09,0x06,0x05,0x2B,0x0E,0x03,0x02,0x1A,0x05,0x00,0x04,0x14};
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template<> const unsigned int PKCS_DigestDecoration<SHA>::length = sizeof(PKCS_DigestDecoration<SHA>::decoration);
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void PKCS1v15_SignatureMessageEncodingMethod::ComputeMessageRepresentative(RandomNumberGenerator &rng,
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const byte *recoverableMessage, unsigned int recoverableMessageLength,
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HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
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byte *representative, unsigned int representativeBitLength) const
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{
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unsigned int digestSize = hash.DigestSize();
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if (digestSize + hashIdentifier.second + 10 > representativeBitLength/8)
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throw PK_Signer::KeyTooShort();
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unsigned int pkcsBlockLen = representativeBitLength;
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// convert from bit length to byte length
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if (pkcsBlockLen % 8 != 0)
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{
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representative[0] = 0;
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representative++;
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}
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pkcsBlockLen /= 8;
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representative[0] = 1; // block type 1
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byte *pPadding = representative + 1;
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byte *pDigest = representative + pkcsBlockLen - digestSize;
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byte *pHashId = pDigest - hashIdentifier.second;
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byte *pSeparator = pHashId - 1;
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// pad with 0xff
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memset(pPadding, 0xff, pSeparator-pPadding);
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*pSeparator = 0;
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memcpy(pHashId, hashIdentifier.first, hashIdentifier.second);
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hash.Final(pDigest);
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}
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}
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