You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
99 lines
3.0 KiB
99 lines
3.0 KiB
5 years ago
|
// oaep.cpp - written and placed in the public domain by Wei Dai
|
||
|
|
|
||
|
|
#include "pch.h"
|
||
|
|
|
||
|
|
#ifndef CRYPTOPP_IMPORTS
|
||
|
|
|
||
|
|
#include "oaep.h"
|
||
|
|
#include "stdcpp.h"
|
||
|
|
#include "smartptr.h"
|
||
|
|
|
||
|
|
NAMESPACE_BEGIN(CryptoPP)
|
||
|
|
|
||
|
|
// ********************************************************
|
||
|
|
|
||
|
|
size_t OAEP_Base::MaxUnpaddedLength(size_t paddedLength) const
|
||
|
|
{
|
||
|
|
return SaturatingSubtract(paddedLength/8, 1+2*DigestSize());
|
||
|
|
}
|
||
|
|
|
||
|
|
void OAEP_Base::Pad(RandomNumberGenerator &rng, const byte *input, size_t inputLength, byte *oaepBlock, size_t oaepBlockLen, const NameValuePairs ¶meters) const
|
||
|
|
{
|
||
|
|
assert (inputLength <= MaxUnpaddedLength(oaepBlockLen));
|
||
|
|
|
||
|
|
// convert from bit length to byte length
|
||
|
|
if (oaepBlockLen % 8 != 0)
|
||
|
|
{
|
||
|
|
oaepBlock[0] = 0;
|
||
|
|
oaepBlock++;
|
||
|
|
}
|
||
|
|
oaepBlockLen /= 8;
|
||
|
|
|
||
|
|
member_ptr<HashTransformation> pHash(NewHash());
|
||
|
|
const size_t hLen = pHash->DigestSize();
|
||
|
|
const size_t seedLen = hLen, dbLen = oaepBlockLen-seedLen;
|
||
|
|
byte *const maskedSeed = oaepBlock;
|
||
|
|
byte *const maskedDB = oaepBlock+seedLen;
|
||
|
|
|
||
|
|
ConstByteArrayParameter encodingParameters;
|
||
|
|
parameters.GetValue(Name::EncodingParameters(), encodingParameters);
|
||
|
|
|
||
|
|
// DB = pHash || 00 ... || 01 || M
|
||
|
|
pHash->CalculateDigest(maskedDB, encodingParameters.begin(), encodingParameters.size());
|
||
|
|
memset(maskedDB+hLen, 0, dbLen-hLen-inputLength-1);
|
||
|
|
maskedDB[dbLen-inputLength-1] = 0x01;
|
||
|
|
memcpy(maskedDB+dbLen-inputLength, input, inputLength);
|
||
|
|
|
||
|
|
rng.GenerateBlock(maskedSeed, seedLen);
|
||
|
|
member_ptr<MaskGeneratingFunction> pMGF(NewMGF());
|
||
|
|
pMGF->GenerateAndMask(*pHash, maskedDB, dbLen, maskedSeed, seedLen);
|
||
|
|
pMGF->GenerateAndMask(*pHash, maskedSeed, seedLen, maskedDB, dbLen);
|
||
|
|
}
|
||
|
|
|
||
|
|
DecodingResult OAEP_Base::Unpad(const byte *oaepBlock, size_t oaepBlockLen, byte *output, const NameValuePairs ¶meters) const
|
||
|
|
{
|
||
|
|
bool invalid = false;
|
||
|
|
|
||
|
|
// convert from bit length to byte length
|
||
|
|
if (oaepBlockLen % 8 != 0)
|
||
|
|
{
|
||
|
|
invalid = (oaepBlock[0] != 0) || invalid;
|
||
|
|
oaepBlock++;
|
||
|
|
}
|
||
|
|
oaepBlockLen /= 8;
|
||
|
|
|
||
|
|
member_ptr<HashTransformation> pHash(NewHash());
|
||
|
|
const size_t hLen = pHash->DigestSize();
|
||
|
|
const size_t seedLen = hLen, dbLen = oaepBlockLen-seedLen;
|
||
|
|
|
||
|
|
invalid = (oaepBlockLen < 2*hLen+1) || invalid;
|
||
|
|
|
||
|
|
SecByteBlock t(oaepBlock, oaepBlockLen);
|
||
|
|
byte *const maskedSeed = t;
|
||
|
|
byte *const maskedDB = t+seedLen;
|
||
|
|
|
||
|
|
member_ptr<MaskGeneratingFunction> pMGF(NewMGF());
|
||
|
|
pMGF->GenerateAndMask(*pHash, maskedSeed, seedLen, maskedDB, dbLen);
|
||
|
|
pMGF->GenerateAndMask(*pHash, maskedDB, dbLen, maskedSeed, seedLen);
|
||
|
|
|
||
|
|
ConstByteArrayParameter encodingParameters;
|
||
|
|
parameters.GetValue(Name::EncodingParameters(), encodingParameters);
|
||
|
|
|
||
|
|
// DB = pHash' || 00 ... || 01 || M
|
||
|
|
byte *M = std::find(maskedDB+hLen, maskedDB+dbLen, 0x01);
|
||
|
|
invalid = (M == maskedDB+dbLen) || invalid;
|
||
|
|
invalid = (std::find_if(maskedDB+hLen, M, std::bind2nd(std::not_equal_to<byte>(), byte(0))) != M) || invalid;
|
||
|
|
invalid = !pHash->VerifyDigest(maskedDB, encodingParameters.begin(), encodingParameters.size()) || invalid;
|
||
|
|
|
||
|
|
if (invalid)
|
||
|
|
return DecodingResult();
|
||
|
|
|
||
|
|
M++;
|
||
|
|
memcpy(output, M, maskedDB+dbLen-M);
|
||
|
|
return DecodingResult(maskedDB+dbLen-M);
|
||
|
|
}
|
||
|
|
|
||
|
|
NAMESPACE_END
|
||
|
|
|
||
|
|
#endif
|