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// rabbit.cpp - written and placed in the public domain by Jeffrey Walton
// based on public domain code by Martin Boesgaard, Mette Vesterager,
// Thomas Pedersen, Jesper Christiansen and Ove Scavenius.
//
// The reference materials and source files are available at
// The eSTREAM Project, http://www.ecrypt.eu.org/stream/e2-rabbit.html.
#include "pch.h"
#include "config.h"
#include "rabbit.h"
#include "secblock.h"
#include "misc.h"
ANONYMOUS_NAMESPACE_BEGIN
using CryptoPP::word32;
using CryptoPP::word64;
using CryptoPP::rotlConstant;
word32 G_func(word32 x)
{
#if 0
/* Temporary variables */
word32 a, b, h, l;
/* Construct high and low argument for squaring */
a = x & 0xFFFF;
b = x >> 16;
/* Calculate high and low result of squaring */
h = (((static_cast<word32>(a*a) >> 17U) + static_cast<word32>(a*b)) >> 15U) + b*b;
l = x*x;
/* Return high XOR low */
return static_cast<word32>(h^l);
#endif
// Thanks to Jack Lloyd for suggesting the 64-bit multiply.
word64 z = x;
z *= x;
return static_cast<word32>((z >> 32) ^ z);
}
word32 NextState(word32 c[8], word32 x[8], word32 carry)
{
/* Temporary variables */
word32 g[8], c_old[8], i;
/* Save old counter values */
for (i = 0; i<8; i++)
c_old[i] = c[i];
/* Calculate new counter values */
c[0] = static_cast<word32>(c[0] + 0x4D34D34D + carry);
c[1] = static_cast<word32>(c[1] + 0xD34D34D3 + (c[0] < c_old[0]));
c[2] = static_cast<word32>(c[2] + 0x34D34D34 + (c[1] < c_old[1]));
c[3] = static_cast<word32>(c[3] + 0x4D34D34D + (c[2] < c_old[2]));
c[4] = static_cast<word32>(c[4] + 0xD34D34D3 + (c[3] < c_old[3]));
c[5] = static_cast<word32>(c[5] + 0x34D34D34 + (c[4] < c_old[4]));
c[6] = static_cast<word32>(c[6] + 0x4D34D34D + (c[5] < c_old[5]));
c[7] = static_cast<word32>(c[7] + 0xD34D34D3 + (c[6] < c_old[6]));
carry = (c[7] < c_old[7]);
/* Calculate the g-values */
for (i = 0; i<8; i++)
g[i] = G_func(static_cast<word32>(x[i] + c[i]));
/* Calculate new state values */
x[0] = static_cast<word32>(g[0] + rotlConstant<16>(g[7]) + rotlConstant<16>(g[6]));
x[1] = static_cast<word32>(g[1] + rotlConstant<8>(g[0]) + g[7]);
x[2] = static_cast<word32>(g[2] + rotlConstant<16>(g[1]) + rotlConstant<16>(g[0]));
x[3] = static_cast<word32>(g[3] + rotlConstant<8>(g[2]) + g[1]);
x[4] = static_cast<word32>(g[4] + rotlConstant<16>(g[3]) + rotlConstant<16>(g[2]));
x[5] = static_cast<word32>(g[5] + rotlConstant<8>(g[4]) + g[3]);
x[6] = static_cast<word32>(g[6] + rotlConstant<16>(g[5]) + rotlConstant<16>(g[4]));
x[7] = static_cast<word32>(g[7] + rotlConstant<8>(g[6]) + g[5]);
return carry;
}
ANONYMOUS_NAMESPACE_END
NAMESPACE_BEGIN(CryptoPP)
void RabbitPolicy::CipherSetKey(const NameValuePairs ¶ms, const byte *userKey, size_t keylen)
{
/* Generate four subkeys */
CRYPTOPP_UNUSED(params);
GetUserKey(LITTLE_ENDIAN_ORDER, m_t.begin(), 4, userKey, keylen);
/* Generate initial state variables */
m_mx[0] = m_t[0];
m_mx[2] = m_t[1];
m_mx[4] = m_t[2];
m_mx[6] = m_t[3];
m_mx[1] = static_cast<word32>(m_t[3] << 16) | (m_t[2] >> 16);
m_mx[3] = static_cast<word32>(m_t[0] << 16) | (m_t[3] >> 16);
m_mx[5] = static_cast<word32>(m_t[1] << 16) | (m_t[0] >> 16);
m_mx[7] = static_cast<word32>(m_t[2] << 16) | (m_t[1] >> 16);
/* Generate initial counter values */
m_mc[0] = rotlConstant<16>(m_t[2]);
m_mc[2] = rotlConstant<16>(m_t[3]);
m_mc[4] = rotlConstant<16>(m_t[0]);
m_mc[6] = rotlConstant<16>(m_t[1]);
m_mc[1] = (m_t[0] & 0xFFFF0000) | (m_t[1] & 0xFFFF);
m_mc[3] = (m_t[1] & 0xFFFF0000) | (m_t[2] & 0xFFFF);
m_mc[5] = (m_t[2] & 0xFFFF0000) | (m_t[3] & 0xFFFF);
m_mc[7] = (m_t[3] & 0xFFFF0000) | (m_t[0] & 0xFFFF);
/* Clear carry bit */
m_mcy = 0;
/* Iterate the system four times */
for (unsigned int i = 0; i<4; i++)
m_mcy = NextState(m_mc, m_mx, m_mcy);
/* Modify the counters */
for (unsigned int i = 0; i<8; i++)
m_mc[i] ^= m_mx[(i + 4) & 0x7];
/* Copy master instance to work instance */
for (unsigned int i = 0; i<8; i++)
{
m_wx[i] = m_mx[i];
m_wc[i] = m_mc[i];
}
m_wcy = m_mcy;
}
void RabbitPolicy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
{
byte* out = output;
for (size_t i = 0; i<iterationCount; ++i, out += 16)
{
/* Iterate the system */
m_wcy = NextState(m_wc, m_wx, m_wcy);
/* Encrypt/decrypt 16 bytes of data */
PutWord(false, LITTLE_ENDIAN_ORDER, out + 0, m_wx[0] ^ (m_wx[5] >> 16) ^ (m_wx[3] << 16));
PutWord(false, LITTLE_ENDIAN_ORDER, out + 4, m_wx[2] ^ (m_wx[7] >> 16) ^ (m_wx[5] << 16));
PutWord(false, LITTLE_ENDIAN_ORDER, out + 8, m_wx[4] ^ (m_wx[1] >> 16) ^ (m_wx[7] << 16));
PutWord(false, LITTLE_ENDIAN_ORDER, out + 12, m_wx[6] ^ (m_wx[3] >> 16) ^ (m_wx[1] << 16));
}
// If AdditiveCipherTemplate does not have an accumulated keystream
// then it will ask OperateKeystream to generate one. Optionally it
// will ask for an XOR of the input with the keystream while
// writing the result to the output buffer. In all cases the
// keystream is written to the output buffer. The optional part is
// adding the input buffer and keystream.
if ((operation & EnumToInt(INPUT_NULL)) != EnumToInt(INPUT_NULL))
xorbuf(output, input, GetBytesPerIteration() * iterationCount);
}
void RabbitWithIVPolicy::CipherSetKey(const NameValuePairs ¶ms, const byte *userKey, size_t keylen)
{
/* Generate four subkeys */
CRYPTOPP_UNUSED(params);
GetUserKey(LITTLE_ENDIAN_ORDER, m_t.begin(), 4, userKey, keylen);
/* Generate initial state variables */
m_mx[0] = m_t[0];
m_mx[2] = m_t[1];
m_mx[4] = m_t[2];
m_mx[6] = m_t[3];
m_mx[1] = static_cast<word32>(m_t[3] << 16) | (m_t[2] >> 16);
m_mx[3] = static_cast<word32>(m_t[0] << 16) | (m_t[3] >> 16);
m_mx[5] = static_cast<word32>(m_t[1] << 16) | (m_t[0] >> 16);
m_mx[7] = static_cast<word32>(m_t[2] << 16) | (m_t[1] >> 16);
/* Generate initial counter values */
m_mc[0] = rotlConstant<16>(m_t[2]);
m_mc[2] = rotlConstant<16>(m_t[3]);
m_mc[4] = rotlConstant<16>(m_t[0]);
m_mc[6] = rotlConstant<16>(m_t[1]);
m_mc[1] = (m_t[0] & 0xFFFF0000) | (m_t[1] & 0xFFFF);
m_mc[3] = (m_t[1] & 0xFFFF0000) | (m_t[2] & 0xFFFF);
m_mc[5] = (m_t[2] & 0xFFFF0000) | (m_t[3] & 0xFFFF);
m_mc[7] = (m_t[3] & 0xFFFF0000) | (m_t[0] & 0xFFFF);
/* Clear carry bit */
m_mcy = 0;
/* Iterate the system four times */
for (unsigned int i = 0; i<4; i++)
m_mcy = NextState(m_mc, m_mx, m_mcy);
/* Modify the counters */
for (unsigned int i = 0; i<8; i++)
m_mc[i] ^= m_mx[(i + 4) & 0x7];
/* Copy master instance to work instance */
for (unsigned int i = 0; i<8; i++)
{
m_wx[i] = m_mx[i];
m_wc[i] = m_mc[i];
}
m_wcy = m_mcy;
}
void RabbitWithIVPolicy::CipherResynchronize(byte *keystreamBuffer, const byte *iv, size_t length)
{
CRYPTOPP_UNUSED(keystreamBuffer);
CRYPTOPP_UNUSED(length);
CRYPTOPP_ASSERT(length == 8);
/* Generate four subvectors */
GetBlock<word32, LittleEndian> v(iv); v(m_t[0])(m_t[2]);
m_t[1] = (m_t[0] >> 16) | (m_t[2] & 0xFFFF0000);
m_t[3] = (m_t[2] << 16) | (m_t[0] & 0x0000FFFF);
/* Modify counter values */
m_wc[0] = m_mc[0] ^ m_t[0];
m_wc[1] = m_mc[1] ^ m_t[1];
m_wc[2] = m_mc[2] ^ m_t[2];
m_wc[3] = m_mc[3] ^ m_t[3];
m_wc[4] = m_mc[4] ^ m_t[0];
m_wc[5] = m_mc[5] ^ m_t[1];
m_wc[6] = m_mc[6] ^ m_t[2];
m_wc[7] = m_mc[7] ^ m_t[3];
/* Copy state variables */
for (unsigned int i = 0; i<8; i++)
m_wx[i] = m_mx[i];
m_wcy = m_mcy;
/* Iterate the system four times */
for (unsigned int i = 0; i<4; i++)
m_wcy = NextState(m_wc, m_wx, m_wcy);
}
void RabbitWithIVPolicy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
{
byte* out = output;
for (unsigned int i = 0; i<iterationCount; ++i, out += 16)
{
/* Iterate the system */
m_wcy = NextState(m_wc, m_wx, m_wcy);
/* Encrypt/decrypt 16 bytes of data */
PutWord(false, LITTLE_ENDIAN_ORDER, out + 0, m_wx[0] ^ (m_wx[5] >> 16) ^ (m_wx[3] << 16));
PutWord(false, LITTLE_ENDIAN_ORDER, out + 4, m_wx[2] ^ (m_wx[7] >> 16) ^ (m_wx[5] << 16));
PutWord(false, LITTLE_ENDIAN_ORDER, out + 8, m_wx[4] ^ (m_wx[1] >> 16) ^ (m_wx[7] << 16));
PutWord(false, LITTLE_ENDIAN_ORDER, out + 12, m_wx[6] ^ (m_wx[3] >> 16) ^ (m_wx[1] << 16));
}
// If AdditiveCipherTemplate does not have an accumulated keystream
// then it will ask OperateKeystream to generate one. Optionally it
// will ask for an XOR of the input with the keystream while
// writing the result to the output buffer. In all cases the
// keystream is written to the output buffer. The optional part is
// adding the input buffer and keystream.
if ((operation & EnumToInt(INPUT_NULL)) != EnumToInt(INPUT_NULL))
xorbuf(output, input, GetBytesPerIteration() * iterationCount);
}
NAMESPACE_END
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