blowfish.cpp

// blowfish.cpp - originally written and placed in the public domain by Wei Dai
 
#include "pch.h"
#include "blowfish.h"
#include "misc.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
void Blowfish::Base::UncheckedSetKey(const byte *key_string, unsigned int keylength, const NameValuePairs &)
{
    AssertValidKeyLength(keylength);
 
    unsigned i, j=0, k;
    word32 data, dspace[2] = {0, 0};
 
    std::memcpy(pbox, p_init, sizeof(p_init));
    std::memcpy(sbox, s_init, sizeof(s_init));
 
    // Xor key string into encryption key vector
    for (i=0 ; i<ROUNDS+2 ; ++i)
    {
        data = 0 ;
        for (k=0 ; k<4 ; ++k )
            data = (data << 8) | key_string[j++ % keylength];
        pbox[i] ^= data;
    }
 
    crypt_block(dspace, pbox);
 
    for (i=0; i<ROUNDS; i+=2)
        crypt_block(pbox+i, pbox+i+2);
 
    crypt_block(pbox+ROUNDS, sbox);
 
    for (i=0; i<4*256-2; i+=2)
        crypt_block(sbox+i, sbox+i+2);
 
    if (!IsForwardTransformation())
        for (i=0; i<(ROUNDS+2)/2; i++)
            std::swap(pbox[i], pbox[ROUNDS+1-i]);
}
 
// this version is only used to make pbox and sbox
void Blowfish::Base::crypt_block(const word32 in[2], word32 out[2]) const
{
    word32 left = in[0];
    word32 right = in[1];
 
    const word32 *const s=sbox;
    const word32 *p=pbox;
 
    left ^= p[0];
 
    for (unsigned i=0; i<ROUNDS/2; i++)
    {
        right ^= (((s[GETBYTE(left,3)] + s[256+GETBYTE(left,2)])
              ^ s[2*256+GETBYTE(left,1)]) + s[3*256+GETBYTE(left,0)])
              ^ p[2*i+1];
 
        left ^= (((s[GETBYTE(right,3)] + s[256+GETBYTE(right,2)])
             ^ s[2*256+GETBYTE(right,1)]) + s[3*256+GETBYTE(right,0)])
             ^ p[2*i+2];
    }
 
    right ^= p[ROUNDS+1];
 
    out[0] = right;
    out[1] = left;
}
 
void Blowfish::Base::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
    typedef BlockGetAndPut<word32, BigEndian> Block;
 
    word32 left, right;
    Block::Get(inBlock)(left)(right);
 
    const word32 *const s=sbox;
    const word32 *p=pbox;
 
    left ^= p[0];
 
    for (unsigned i=0; i<ROUNDS/2; i++)
    {
        right ^= (((s[GETBYTE(left,3)] + s[256+GETBYTE(left,2)])
              ^ s[2*256+GETBYTE(left,1)]) + s[3*256+GETBYTE(left,0)])
              ^ p[2*i+1];
 
        left ^= (((s[GETBYTE(right,3)] + s[256+GETBYTE(right,2)])
             ^ s[2*256+GETBYTE(right,1)]) + s[3*256+GETBYTE(right,0)])
             ^ p[2*i+2];
    }
 
    right ^= p[ROUNDS+1];
 
    Block::Put(xorBlock, outBlock)(right)(left);
}
 
NAMESPACE_END