DecodingResult TF_VerifierBase::RecoverAndRestart(byte *recoveredMessage, PK_MessageAccumulator &messageAccumulator) const
{
PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
DecodingResult result = GetMessageEncodingInterface().RecoverMessageFromRepresentative(
ma.AccessHash(), GetHashIdentifier(), ma.m_empty, ma.m_representative, MessageRepresentativeBitLength(), recoveredMessage);
ma.m_empty = true;
return result;
}
bool TF_VerifierBase::VerifyAndRestart(PK_MessageAccumulator &messageAccumulator) const
{
PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
bool result = GetMessageEncodingInterface().VerifyMessageRepresentative(
ma.AccessHash(), GetHashIdentifier(), 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;
}
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());
}
unsigned int TF_SignerBase::SignAndRestart(RandomNumberGenerator &rng, PK_MessageAccumulator &messageAccumulator, byte *signature, bool restart) const
{
PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
SecByteBlock representative(MessageRepresentativeLength());
GetMessageEncodingInterface().ComputeMessageRepresentative(rng,
ma.m_recoverableMessage, ma.m_recoverableMessage.size(),
ma.AccessHash(), GetHashIdentifier(), ma.m_empty,
representative, MessageRepresentativeBitLength());
ma.m_empty = true;
Integer r(representative, representative.size());
unsigned int signatureLength = SignatureLength();
GetTrapdoorFunctionInterface().CalculateRandomizedInverse(rng, r).Encode(signature, signatureLength);
return signatureLength;
}
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_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);
}
