blowfish.cpp

各种加密算法的源代码

#include <memory.h>
#include "misc.h"
#include "blowfish.h"

Blowfish::Blowfish(const byte *key_string, unsigned int keylength, CipherDir dir)
    : pbox(ROUNDS+2), sbox(4*256)
{
    int i, j=0, k;
    word32 data, dspace[2] = {0, 0};

    memcpy(pbox, p_init, sizeof(p_init));
    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 (dir==DECRYPTION)
        for (i=0; i<(ROUNDS+2)/2; i++)
            swap(pbox[i], pbox[ROUNDS+1-i]);
}

// this version is only used to make pbox and sbox
void Blowfish::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;

    for (int i=ROUNDS/2; i; i--)
    {
        left ^= *p++;
        right ^= (((s[(byte)(left>>24)] + s[256+(byte)(left>>16)])
              ^ s[2*256+(byte)(left>>8)]) + s[3*256+(byte)left]);

        right ^= *p++;
        left ^= (((s[(byte)(right>>24)] + s[256+(byte)(right>>16)])
             ^ s[2*256+(byte)(right>>8)]) + s[3*256+(byte)right]);
    }

    left ^= *p++;
    right ^= *p ;
    out[0] = right;
    out[1] = left;
}

void Blowfish::ProcessBlock(const byte *in, byte *out)
{
#ifdef LITTLE_ENDIAN
    word32 left = Invert(*(word32 *)in);
    word32 right = Invert(*(word32 *)(in+4));
#else
    word32 left = *(word32 *)in;
    word32 right = *(word32 *)(in+4);
#endif

    const word32 *const s=sbox;
    const word32 *p=pbox;

    for (int i=ROUNDS/2; i; i--)
    {
        left ^= *p++;
        right ^= (((s[(byte)(left>>24)] + s[256+(byte)(left>>16)])
              ^ s[2*256+(byte)(left>>8)]) + s[3*256+(byte)left]);

        right ^= *p++;
        left ^= (((s[(byte)(right>>24)] + s[256+(byte)(right>>16)])
             ^ s[2*256+(byte)(right>>8)]) + s[3*256+(byte)right]);
    }

    left ^= *p++;
    right ^= *p ;

#ifdef LITTLE_ENDIAN
    *(word32 *)out = Invert(right);
    *(word32 *)(out+4) = Invert(left);
#else
    *(word32 *)out = right;
    *(word32 *)(out+4) = left;
#endif
}