Документация по криптоалгоритмам / CRYPTO30 / cryptlib

// cryptlib.cpp - written and placed in the public domain by Wei Dai

#include "pch.h"
#include "cryptlib.h"
#include "misc.h"

#include <memory>

NAMESPACE_BEGIN(CryptoPP)

unsigned int RandomNumberGenerator::GetBit()
{
	return Parity(GetByte());
}

void RandomNumberGenerator::GetBlock(byte *output, unsigned int size)
{
	while (size--)
		*output++ = GetByte();
}

word32 RandomNumberGenerator::GetLong(word32 min, word32 max)
{
	word32 range = max-min;
	const int maxBytes = BytePrecision(range);
	const int maxBits = BitPrecision(range);

	word32 value;

	do
	{
		value = 0;
		for (int i=0; i<maxBytes; i++)
			value = (value << 8) | GetByte();

		value = Crop(value, maxBits);
	} while (value > range);

	return value+min;
}

void StreamCipher::ProcessString(byte *outString, const byte *inString, unsigned int length)
{
	while(length--)
		*outString++ = ProcessByte(*inString++);
}

void StreamCipher::ProcessString(byte *inoutString, unsigned int length)
{
	while(length--)
		*inoutString++ = ProcessByte(*inoutString);
}

bool MessageAuthenticationCode::Verify(const byte *macIn)
{
	SecByteBlock mac(DigestSize());
	Final(mac);
	return memcmp(mac, macIn, DigestSize()) == 0;
}

void BufferedTransformation::TransferTo(BufferedTransformation &target)
{
	SecByteBlock buf(256);
	unsigned int l;

	while ((l=Get(buf, 256)) != 0)
		target.Put(buf, l);
}

unsigned int BufferedTransformation::TransferTo(BufferedTransformation &target, unsigned int size)
{
	SecByteBlock buf(256);
	unsigned int l, total = 0;

	while (size && (l=Get(buf, STDMIN(size, 256U))))
	{
		target.Put(buf, l);
		size -= l;
		total += l;
	}
	return total;
}

void BufferedTransformation::PutShort(word16 value, bool highFirst)
{
	if (highFirst)
	{
		Put(value>>8);
		Put(byte(value));
	}
	else
	{
		Put(byte(value));
		Put(value>>8);
	}
}

void BufferedTransformation::PutLong(word32 value, bool highFirst)
{
	if (highFirst)
	{
		for (int i=0; i<4; i++)
			Put(byte(value>>((3-i)*8)));
	}
	else
	{
		for (int i=0; i<4; i++)
			Put(byte(value>>(i*8)));
	}
}

int BufferedTransformation::GetShort(word16 &value, bool highFirst)
{
	if (MaxRetrieveable()<2)
		return 0;

	byte buf[2];
	Get(buf, 2);

	if (highFirst)
		value = (buf[0] << 8) | buf[1];
	else
		value = (buf[1] << 8) | buf[0];

	return 2;
}

int BufferedTransformation::GetLong(word32 &value, bool highFirst)
{
	if (MaxRetrieveable()<4)
		return 0;

	byte buf[4];
	Get(buf, 4);

	if (highFirst)
		value = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf [3];
	else
		value = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf [0];

	return 4;
}

unsigned int BufferedTransformation::Skip(unsigned int skipMax)
{
	byte b;
	unsigned int skipActual=0;

	while (skipMax-- && Get(b))
		skipActual++;
	return skipActual;
}

unsigned int PK_FixedLengthCryptoSystem::MaxPlainTextLength(unsigned int cipherTextLength) const
{
	if (cipherTextLength == CipherTextLength())
		return MaxPlainTextLength();
	else
		return 0;
}

unsigned int PK_FixedLengthCryptoSystem::CipherTextLength(unsigned int plainTextLength) const
{
	if (plainTextLength <= MaxPlainTextLength())
		return CipherTextLength();
	else
		return 0;
}

unsigned int PK_FixedLengthDecryptor::Decrypt(const byte *cipherText, unsigned int cipherTextLength, byte *plainText)
{
	if (cipherTextLength != CipherTextLength())
		return 0;

	return Decrypt(cipherText, plainText);
}

void PK_Signer::SignMessage(RandomNumberGenerator &rng, const byte *message, unsigned int messageLen, byte *signature) const
{
	std::auto_ptr<HashModule> accumulator(NewMessageAccumulator());
	accumulator->Update(message, messageLen);
	Sign(rng, accumulator.release(), signature);
}

bool PK_Verifier::VerifyMessage(const byte *message, unsigned int messageLen, const byte *sig) const
{
	std::auto_ptr<HashModule> accumulator(NewMessageAccumulator());
	accumulator->Update(message, messageLen);
	return Verify(accumulator.release(), sig);
}

NAMESPACE_END