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// chacha.cpp - written and placed in the public domain by Jeffrey Walton.
// Based on Wei Dai's Salsa20 and Bernstein's reference ChaCha
// family implementation at http://cr.yp.to/chacha.html.
#include "pch.h"
#include "config.h"
#include "chacha.h"
#include "argnames.h"
#include "misc.h"
#include "cpu.h"
NAMESPACE_BEGIN(CryptoPP)
#define CHACHA_QUARTER_ROUND(a,b,c,d) \
a += b; d ^= a; d = rotlConstant<16,word32>(d); \
c += d; b ^= c; b = rotlConstant<12,word32>(b); \
a += b; d ^= a; d = rotlConstant<8,word32>(d); \
c += d; b ^= c; b = rotlConstant<7,word32>(b);
#if defined(CRYPTOPP_DEBUG) && !defined(CRYPTOPP_DOXYGEN_PROCESSING)
void ChaCha_TestInstantiations()
{
ChaCha8::Encryption x1;
ChaCha12::Encryption x2;
ChaCha20::Encryption x3;
}
#endif
template <unsigned int R>
void ChaCha_Policy<R>::CipherSetKey(const NameValuePairs ¶ms, const byte *key, size_t length)
{
CRYPTOPP_UNUSED(params);
CRYPTOPP_ASSERT(length == 16 || length == 32);
// "expand 16-byte k" or "expand 32-byte k"
m_state[0] = 0x61707865;
m_state[1] = (length == 16) ? 0x3120646e : 0x3320646e;
m_state[2] = (length == 16) ? 0x79622d36 : 0x79622d32;
m_state[3] = 0x6b206574;
GetBlock<word32, LittleEndian> get1(key);
get1(m_state[4])(m_state[5])(m_state[6])(m_state[7]);
GetBlock<word32, LittleEndian> get2(key + ((length == 32) ? 16 : 0));
get2(m_state[8])(m_state[9])(m_state[10])(m_state[11]);
}
template <unsigned int R>
void ChaCha_Policy<R>::CipherResynchronize(byte *keystreamBuffer, const byte *IV, size_t length)
{
CRYPTOPP_UNUSED(keystreamBuffer), CRYPTOPP_UNUSED(length);
CRYPTOPP_ASSERT(length==8);
GetBlock<word32, LittleEndian> get(IV);
m_state[12] = m_state[13] = 0;
get(m_state[14])(m_state[15]);
}
template<unsigned int R>
void ChaCha_Policy<R>::SeekToIteration(lword iterationCount)
{
CRYPTOPP_UNUSED(iterationCount);
throw NotImplemented(std::string(ChaCha_Info<R>::StaticAlgorithmName()) + ": SeekToIteration is not yet implemented");
// TODO: these were Salsa20, and Wei re-arranged the state array for SSE2 operations.
// If we can generate some out-of-band test vectors, then test and implement. Also
// see the test vectors in salsa.txt and the use of Seek test argument.
// m_state[8] = (word32)iterationCount;
// m_state[5] = (word32)SafeRightShift<32>(iterationCount);
}
template<unsigned int R>
unsigned int ChaCha_Policy<R>::GetAlignment() const
{
#if CRYPTOPP_SSE2_ASM_AVAILABLE && 0
if (HasSSE2())
return 16;
else
#endif
return GetAlignmentOf<word32>();
}
template<unsigned int R>
unsigned int ChaCha_Policy<R>::GetOptimalBlockSize() const
{
#if CRYPTOPP_SSE2_ASM_AVAILABLE && 0
if (HasSSE2())
return 4*BYTES_PER_ITERATION;
else
#endif
return BYTES_PER_ITERATION;
}
template<unsigned int R>
void ChaCha_Policy<R>::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
{
word32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
while (iterationCount--)
{
x0 = m_state[0]; x1 = m_state[1]; x2 = m_state[2]; x3 = m_state[3];
x4 = m_state[4]; x5 = m_state[5]; x6 = m_state[6]; x7 = m_state[7];
x8 = m_state[8]; x9 = m_state[9]; x10 = m_state[10]; x11 = m_state[11];
x12 = m_state[12]; x13 = m_state[13]; x14 = m_state[14]; x15 = m_state[15];
for (int i = static_cast<int>(ROUNDS); i > 0; i -= 2)
{
CHACHA_QUARTER_ROUND(x0, x4, x8, x12);
CHACHA_QUARTER_ROUND(x1, x5, x9, x13);
CHACHA_QUARTER_ROUND(x2, x6, x10, x14);
CHACHA_QUARTER_ROUND(x3, x7, x11, x15);
CHACHA_QUARTER_ROUND(x0, x5, x10, x15);
CHACHA_QUARTER_ROUND(x1, x6, x11, x12);
CHACHA_QUARTER_ROUND(x2, x7, x8, x13);
CHACHA_QUARTER_ROUND(x3, x4, x9, x14);
}
#undef CHACHA_OUTPUT
#define CHACHA_OUTPUT(x){\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 0, x0 + m_state[0]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 1, x1 + m_state[1]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 2, x2 + m_state[2]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 3, x3 + m_state[3]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 4, x4 + m_state[4]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 5, x5 + m_state[5]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 6, x6 + m_state[6]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 7, x7 + m_state[7]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 8, x8 + m_state[8]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 9, x9 + m_state[9]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 10, x10 + m_state[10]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 11, x11 + m_state[11]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 12, x12 + m_state[12]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 13, x13 + m_state[13]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 14, x14 + m_state[14]);\
CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, LITTLE_ENDIAN_ORDER, 15, x15 + m_state[15]);}
#ifndef CRYPTOPP_DOXYGEN_PROCESSING
CRYPTOPP_KEYSTREAM_OUTPUT_SWITCH(CHACHA_OUTPUT, BYTES_PER_ITERATION);
#endif
++m_state[12];
m_state[13] += static_cast<word32>(m_state[12] == 0);
}
}
template class ChaCha_Policy<8>;
template class ChaCha_Policy<12>;
template class ChaCha_Policy<20>;
NAMESPACE_END
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