hc256.cpp

// hc256.cpp - written and placed in the public domain by Jeffrey Walton
//             based on public domain code by Hongjun Wu.
//
//             The reference materials and source files are available at
//             The eSTREAM Project, http://www.ecrypt.eu.org/stream/hc256.html.
 
#include "pch.h"
#include "config.h"
 
#include "hc256.h"
#include "secblock.h"
#include "misc.h"
 
ANONYMOUS_NAMESPACE_BEGIN
 
using CryptoPP::word32;
using CryptoPP::rotrConstant;
 
inline word32 f1(word32 x)
{
    return rotrConstant<7>(x) ^ rotrConstant<18>(x) ^ (x >> 3);
}
 
inline word32 f2(word32 x)
{
    return rotrConstant<17>(x) ^ rotrConstant<19>(x) ^ (x >> 10);
}
 
ANONYMOUS_NAMESPACE_END
 
NAMESPACE_BEGIN(CryptoPP)
 
inline word32 HC256Policy::H1(word32 u)
{
    word32 tem;
    byte a, b, c, d;
    a = (byte)(u);
    b = (byte)(u >> 8);
    c = (byte)(u >> 16);
    d = (byte)(u >> 24);
    tem = m_Q[a] + m_Q[256 + b] + m_Q[512 + c] + m_Q[768 + d];
    return (tem);
}
 
inline word32 HC256Policy::H2(word32 u)
{
    word32 tem;
    byte a, b, c, d;
    a = (byte)(u);
    b = (byte)(u >> 8);
    c = (byte)(u >> 16);
    d = (byte)(u >> 24);
    tem = m_P[a] + m_P[256 + b] + m_P[512 + c] + m_P[768 + d];
    return (tem);
}
 
inline word32 HC256Policy::Generate() /*one step of the cipher*/
{
    word32 i, i3, i10, i12, i1023;
    word32 output;
 
    i = m_ctr & 0x3ff;
    i3 = (i - 3) & 0x3ff;
    i10 = (i - 10) & 0x3ff;
    i12 = (i - 12) & 0x3ff;
    i1023 = (i - 1023) & 0x3ff;
 
    if (m_ctr < 1024) {
        m_P[i] = m_P[i] + m_P[i10] + (rotrConstant<10>(m_P[i3]) ^ rotrConstant<23>(m_P[i1023])) + m_Q[(m_P[i3] ^ m_P[i1023]) & 0x3ff];
        output = H1(m_P[i12]) ^ m_P[i];
    }
    else {
        m_Q[i] = m_Q[i] + m_Q[i10] + (rotrConstant<10>(m_Q[i3]) ^ rotrConstant<23>(m_Q[i1023])) + m_P[(m_Q[i3] ^ m_Q[i1023]) & 0x3ff];
        output = H2(m_Q[i12]) ^ m_Q[i];
    }
    m_ctr = (m_ctr + 1) & 0x7ff;
    return (output);
}
 
void HC256Policy::CipherSetKey(const NameValuePairs &params, const byte *userKey, size_t keylen)
{
    CRYPTOPP_UNUSED(params); CRYPTOPP_UNUSED(keylen);
    CRYPTOPP_ASSERT(keylen == 32);
 
    for (unsigned int i = 0; i < 8; i++)
        m_key[i] = 0;
 
    for (unsigned int i = 0; i < 32; i++)
    {
        m_key[i >> 2] = m_key[i >> 2] | userKey[i];
        m_key[i >> 2] = rotlConstant<8>(m_key[i >> 2]);
    }
}
 
void HC256Policy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
{
    while (iterationCount--)
    {
        PutWord(false, LITTLE_ENDIAN_ORDER, output +  0, Generate());
        PutWord(false, LITTLE_ENDIAN_ORDER, output +  4, Generate());
        PutWord(false, LITTLE_ENDIAN_ORDER, output +  8, Generate());
        PutWord(false, LITTLE_ENDIAN_ORDER, output + 12, Generate());
 
        // 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, BYTES_PER_ITERATION);
            input += BYTES_PER_ITERATION;
        }
 
        output += BYTES_PER_ITERATION;
    }
}
 
void HC256Policy::CipherResynchronize(byte *keystreamBuffer, const byte *iv, size_t length)
{
    CRYPTOPP_UNUSED(keystreamBuffer); CRYPTOPP_UNUSED(length);
    CRYPTOPP_ASSERT(length == 32);
 
    /* initialize the iv */
    word32 W[2560];
    for (unsigned int i = 0; i < 8; i++)
        m_iv[i] = 0;
 
    for (unsigned int i = 0; i < 32; i++)
    {
        m_iv[i >> 2] = m_iv[i >> 2] | iv[i];
        m_iv[i >> 2] = rotlConstant<8>(m_iv[i >> 2]);
    }
 
    /* setup the table P and Q */
 
    for (unsigned int i = 0; i < 8; i++)
        W[i] = m_key[i];
    for (unsigned int i = 8; i < 16; i++)
        W[i] = m_iv[i - 8];
 
    for (unsigned int i = 16; i < 2560; i++)
        W[i] = f2(W[i - 2]) + W[i - 7] + f1(W[i - 15]) + W[i - 16] + i;
 
    for (unsigned int i = 0; i < 1024; i++)
        m_P[i] = W[i + 512];
    for (unsigned int i = 0; i < 1024; i++)
        m_Q[i] = W[i + 1536];
 
    m_ctr = 0;
 
    /* run the cipher 4096 steps before generating the output */
    for (unsigned int i = 0; i < 4096; i++)
        Generate();
}
 
NAMESPACE_END