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// pubkey.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#ifndef CRYPTOPP_IMPORTS
#include "pubkey.h"
NAMESPACE_BEGIN(CryptoPP)
void P1363_MGF1KDF2_Common(HashTransformation &hash, byte *output, size_t outputLength, const byte *input, size_t inputLength, const byte *derivationParams, size_t derivationParamsLength, bool mask, unsigned int counterStart)
{
ArraySink *sink;
HashFilter filter(hash, sink = mask ? new ArrayXorSink(output, outputLength) : new ArraySink(output, outputLength));
word32 counter = counterStart;
while (sink->AvailableSize() > 0)
{
filter.Put(input, inputLength);
filter.PutWord32(counter++);
filter.Put(derivationParams, derivationParamsLength);
filter.MessageEnd();
}
}
bool PK_DeterministicSignatureMessageEncodingMethod::VerifyMessageRepresentative(
HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
byte *representative, size_t representativeBitLength) const
{
SecByteBlock computedRepresentative(BitsToBytes(representativeBitLength));
ComputeMessageRepresentative(NullRNG(), NULL, 0, hash, hashIdentifier, messageEmpty, computedRepresentative, representativeBitLength);
return VerifyBufsEqual(representative, computedRepresentative, computedRepresentative.size());
}
bool PK_RecoverableSignatureMessageEncodingMethod::VerifyMessageRepresentative(
HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
byte *representative, size_t representativeBitLength) const
{
SecByteBlock recoveredMessage(MaxRecoverableLength(representativeBitLength, hashIdentifier.second, hash.DigestSize()));
DecodingResult result = RecoverMessageFromRepresentative(
hash, hashIdentifier, messageEmpty, representative, representativeBitLength, recoveredMessage);
return result.isValidCoding && result.messageLength == 0;
}
void TF_SignerBase::InputRecoverableMessage(PK_MessageAccumulator &messageAccumulator, const byte *recoverableMessage, size_t recoverableMessageLength) const
{
PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
HashIdentifier id = GetHashIdentifier();
const MessageEncodingInterface &encoding = GetMessageEncodingInterface();
if (MessageRepresentativeBitLength() < encoding.MinRepresentativeBitLength(id.second, ma.AccessHash().DigestSize()))
throw PK_SignatureScheme::KeyTooShort();
size_t maxRecoverableLength = encoding.MaxRecoverableLength(MessageRepresentativeBitLength(), GetHashIdentifier().second, ma.AccessHash().DigestSize());
if (maxRecoverableLength == 0)
{throw NotImplemented("TF_SignerBase: this algorithm does not support messsage recovery or the key is too short");}
if (recoverableMessageLength > maxRecoverableLength)
throw InvalidArgument("TF_SignerBase: the recoverable message part is too long for the given key and algorithm");
ma.m_recoverableMessage.Assign(recoverableMessage, recoverableMessageLength);
encoding.ProcessRecoverableMessage(
ma.AccessHash(),
recoverableMessage, recoverableMessageLength,
NULL, 0, ma.m_semisignature);
}
size_t TF_SignerBase::SignAndRestart(RandomNumberGenerator &rng, PK_MessageAccumulator &messageAccumulator, byte *signature, bool restart) const
{
PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
HashIdentifier id = GetHashIdentifier();
const MessageEncodingInterface &encoding = GetMessageEncodingInterface();
if (MessageRepresentativeBitLength() < encoding.MinRepresentativeBitLength(id.second, ma.AccessHash().DigestSize()))
throw PK_SignatureScheme::KeyTooShort();
SecByteBlock representative(MessageRepresentativeLength());
encoding.ComputeMessageRepresentative(rng,
ma.m_recoverableMessage, ma.m_recoverableMessage.size(),
ma.AccessHash(), id, ma.m_empty,
representative, MessageRepresentativeBitLength());
ma.m_empty = true;
Integer r(representative, representative.size());
size_t signatureLength = SignatureLength();
GetTrapdoorFunctionInterface().CalculateRandomizedInverse(rng, r).Encode(signature, signatureLength);
return signatureLength;
}
void TF_VerifierBase::InputSignature(PK_MessageAccumulator &messageAccumulator, const byte *signature, size_t signatureLength) const
{
PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
HashIdentifier id = GetHashIdentifier();
const MessageEncodingInterface &encoding = GetMessageEncodingInterface();
if (MessageRepresentativeBitLength() < encoding.MinRepresentativeBitLength(id.second, ma.AccessHash().DigestSize()))
throw PK_SignatureScheme::KeyTooShort();
ma.m_representative.New(MessageRepresentativeLength());
Integer x = GetTrapdoorFunctionInterface().ApplyFunction(Integer(signature, signatureLength));
if (x.BitCount() > MessageRepresentativeBitLength())
x = Integer::Zero(); // don't return false here to prevent timing attack
x.Encode(ma.m_representative, ma.m_representative.size());
}
bool TF_VerifierBase::VerifyAndRestart(PK_MessageAccumulator &messageAccumulator) const
{
PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
HashIdentifier id = GetHashIdentifier();
const MessageEncodingInterface &encoding = GetMessageEncodingInterface();
if (MessageRepresentativeBitLength() < encoding.MinRepresentativeBitLength(id.second, ma.AccessHash().DigestSize()))
throw PK_SignatureScheme::KeyTooShort();
bool result = encoding.VerifyMessageRepresentative(
ma.AccessHash(), id, ma.m_empty, ma.m_representative, MessageRepresentativeBitLength());
ma.m_empty = true;
return result;
}
DecodingResult TF_VerifierBase::RecoverAndRestart(byte *recoveredMessage, PK_MessageAccumulator &messageAccumulator) const
{
PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
HashIdentifier id = GetHashIdentifier();
const MessageEncodingInterface &encoding = GetMessageEncodingInterface();
if (MessageRepresentativeBitLength() < encoding.MinRepresentativeBitLength(id.second, ma.AccessHash().DigestSize()))
throw PK_SignatureScheme::KeyTooShort();
DecodingResult result = encoding.RecoverMessageFromRepresentative(
ma.AccessHash(), id, ma.m_empty, ma.m_representative, MessageRepresentativeBitLength(), recoveredMessage);
ma.m_empty = true;
return result;
}
DecodingResult TF_DecryptorBase::Decrypt(RandomNumberGenerator &rng, const byte *ciphertext, size_t ciphertextLength, byte *plaintext, const NameValuePairs ¶meters) const
{
if (ciphertextLength != FixedCiphertextLength())
throw InvalidArgument(AlgorithmName() + ": ciphertext length of " + IntToString(ciphertextLength) + " doesn't match the required length of " + IntToString(FixedCiphertextLength()) + " for this key");
SecByteBlock paddedBlock(PaddedBlockByteLength());
Integer x = GetTrapdoorFunctionInterface().CalculateInverse(rng, Integer(ciphertext, ciphertextLength));
if (x.ByteCount() > paddedBlock.size())
x = Integer::Zero(); // don't return false here to prevent timing attack
x.Encode(paddedBlock, paddedBlock.size());
return GetMessageEncodingInterface().Unpad(paddedBlock, PaddedBlockBitLength(), plaintext, parameters);
}
void TF_EncryptorBase::Encrypt(RandomNumberGenerator &rng, const byte *plaintext, size_t plaintextLength, byte *ciphertext, const NameValuePairs ¶meters) const
{
if (plaintextLength > FixedMaxPlaintextLength())
{
if (FixedMaxPlaintextLength() < 1)
throw InvalidArgument(AlgorithmName() + ": this key is too short to encrypt any messages");
else
throw InvalidArgument(AlgorithmName() + ": message length of " + IntToString(plaintextLength) + " exceeds the maximum of " + IntToString(FixedMaxPlaintextLength()) + " for this public key");
}
SecByteBlock paddedBlock(PaddedBlockByteLength());
GetMessageEncodingInterface().Pad(rng, plaintext, plaintextLength, paddedBlock, PaddedBlockBitLength(), parameters);
GetTrapdoorFunctionInterface().ApplyRandomizedFunction(rng, Integer(paddedBlock, paddedBlock.size())).Encode(ciphertext, FixedCiphertextLength());
}
NAMESPACE_END
#endif
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