pkcspad.cpp
// pkcspad.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#ifndef CRYPTOPP_PKCSPAD_CPP // SunCC workaround: compiler could cause this file to be included twice
#define CRYPTOPP_PKCSPAD_CPP
#include "pkcspad.h"
#include "misc.h"
#include <assert.h>
NAMESPACE_BEGIN(CryptoPP)
// more in dll.cpp
template<> const byte PKCS_DigestDecoration<Weak1::MD2>::decoration[] = {0x30,0x20,0x30,0x0c,0x06,0x08,0x2a,0x86,0x48,0x86,0xf7,0x0d,0x02,0x02,0x05,0x00,0x04,0x10};
template<> const unsigned int PKCS_DigestDecoration<Weak1::MD2>::length = sizeof(PKCS_DigestDecoration<Weak1::MD2>::decoration);
template<> const byte PKCS_DigestDecoration<Weak1::MD5>::decoration[] = {0x30,0x20,0x30,0x0c,0x06,0x08,0x2a,0x86,0x48,0x86,0xf7,0x0d,0x02,0x05,0x05,0x00,0x04,0x10};
template<> const unsigned int PKCS_DigestDecoration<Weak1::MD5>::length = sizeof(PKCS_DigestDecoration<Weak1::MD5>::decoration);
template<> const byte PKCS_DigestDecoration<RIPEMD160>::decoration[] = {0x30,0x21,0x30,0x09,0x06,0x05,0x2b,0x24,0x03,0x02,0x01,0x05,0x00,0x04,0x14};
template<> const unsigned int PKCS_DigestDecoration<RIPEMD160>::length = sizeof(PKCS_DigestDecoration<RIPEMD160>::decoration);
template<> const byte PKCS_DigestDecoration<Tiger>::decoration[] = {0x30,0x29,0x30,0x0D,0x06,0x09,0x2B,0x06,0x01,0x04,0x01,0xDA,0x47,0x0C,0x02,0x05,0x00,0x04,0x18};
template<> const unsigned int PKCS_DigestDecoration<Tiger>::length = sizeof(PKCS_DigestDecoration<Tiger>::decoration);
size_t PKCS_EncryptionPaddingScheme::MaxUnpaddedLength(size_t paddedLength) const
{
return SaturatingSubtract(paddedLength/8, 10U);
}
void PKCS_EncryptionPaddingScheme::Pad(RandomNumberGenerator& rng, const byte *input, size_t inputLen, byte *pkcsBlock, size_t pkcsBlockLen, const NameValuePairs& parameters) const
{
CRYPTOPP_UNUSED(parameters);
assert (inputLen <= MaxUnpaddedLength(pkcsBlockLen)); // this should be checked by caller
// convert from bit length to byte length
if (pkcsBlockLen % 8 != 0)
{
pkcsBlock[0] = 0;
pkcsBlock++;
}
pkcsBlockLen /= 8;
pkcsBlock[0] = 2; // block type 2
// pad with non-zero random bytes
for (unsigned i = 1; i < pkcsBlockLen-inputLen-1; i++)
pkcsBlock[i] = (byte)rng.GenerateWord32(1, 0xff);
pkcsBlock[pkcsBlockLen-inputLen-1] = 0; // separator
memcpy(pkcsBlock+pkcsBlockLen-inputLen, input, inputLen);
}
DecodingResult PKCS_EncryptionPaddingScheme::Unpad(const byte *pkcsBlock, size_t pkcsBlockLen, byte *output, const NameValuePairs& parameters) const
{
CRYPTOPP_UNUSED(parameters);
bool invalid = false;
size_t maxOutputLen = MaxUnpaddedLength(pkcsBlockLen);
// convert from bit length to byte length
if (pkcsBlockLen % 8 != 0)
{
invalid = (pkcsBlock[0] != 0) || invalid;
pkcsBlock++;
}
pkcsBlockLen /= 8;
// Require block type 2.
invalid = (pkcsBlock[0] != 2) || invalid;
// skip past the padding until we find the separator
size_t i=1;
while (i<pkcsBlockLen && pkcsBlock[i++]) { // null body
}
assert(i==pkcsBlockLen || pkcsBlock[i-1]==0);
size_t outputLen = pkcsBlockLen - i;
invalid = (outputLen > maxOutputLen) || invalid;
if (invalid)
return DecodingResult();
memcpy (output, pkcsBlock+i, outputLen);
return DecodingResult(outputLen);
}
// ********************************************************
#ifndef CRYPTOPP_IMPORTS
void PKCS1v15_SignatureMessageEncodingMethod::ComputeMessageRepresentative(RandomNumberGenerator &rng,
const byte *recoverableMessage, size_t recoverableMessageLength,
HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
byte *representative, size_t representativeBitLength) const
{
CRYPTOPP_UNUSED(rng), CRYPTOPP_UNUSED(recoverableMessage), CRYPTOPP_UNUSED(recoverableMessageLength);
CRYPTOPP_UNUSED(messageEmpty), CRYPTOPP_UNUSED(hashIdentifier);
assert(representativeBitLength >= MinRepresentativeBitLength(hashIdentifier.second, hash.DigestSize()));
size_t pkcsBlockLen = representativeBitLength;
// convert from bit length to byte length
if (pkcsBlockLen % 8 != 0)
{
representative[0] = 0;
representative++;
}
pkcsBlockLen /= 8;
representative[0] = 1; // block type 1
unsigned int digestSize = hash.DigestSize();
byte *pPadding = representative + 1;
byte *pDigest = representative + pkcsBlockLen - digestSize;
byte *pHashId = pDigest - hashIdentifier.second;
byte *pSeparator = pHashId - 1;
// pad with 0xff
memset(pPadding, 0xff, pSeparator-pPadding);
*pSeparator = 0;
memcpy(pHashId, hashIdentifier.first, hashIdentifier.second);
hash.Final(pDigest);
}
#endif
NAMESPACE_END
#endif
PKCS_EncryptionPaddingScheme::MaxUnpaddedLength
size_t MaxUnpaddedLength(size_t paddedLength) const
max size of unpadded message in bytes, given max size of padded message in bits (1 less than size of ...
Definition: pkcspad.cpp:27
HashTransformation
Interface for hash functions and data processing part of MACs.
Definition: cryptlib.h:922
RandomNumberGenerator
Interface for random number generators.
Definition: cryptlib.h:1186
misc.h
Utility functions for the Crypto++ library.
DecodingResult
Returns a decoding results.
Definition: cryptlib.h:236
RandomNumberGenerator::GenerateWord32
virtual word32 GenerateWord32(word32 min=0, word32 max=0xffffffffUL)
Generate a random 32 bit word in the range min to max, inclusive.
Definition: cryptlib.cpp:302
PKCS_DigestDecoration
Definition: pkcspad.h:29
HashTransformation::DigestSize
virtual unsigned int DigestSize() const =0
Provides the digest size of the hash.
CryptoPP
Crypto++ library namespace.
SaturatingSubtract
T1 SaturatingSubtract(const T1 &a, const T2 &b)
Performs a saturating subtract clamped at 0.
Definition: misc.h:961
NameValuePairs
Interface for retrieving values given their names.
Definition: cryptlib.h:277
HashTransformation::Final
virtual void Final(byte *digest)
Computes the hash of the current message.
Definition: cryptlib.h:954