cbc128.c

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/* ====================================================================
 * Copyright (c) 2008 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
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 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
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 *    distribution.
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 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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 *    "This product includes software developed by the OpenSSL Project
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#include <openssl/crypto.h>
#include "modes_lcl.h"
#include <string.h>

#ifndef MODES_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif
#include <assert.h>

#ifndef STRICT_ALIGNMENT
#  define STRICT_ALIGNMENT 0
#endif

void CRYPTO_cbc128_encrypt(const unsigned char *in, unsigned char *out,
            size_t len, const void *key,
            unsigned char ivec[16], block128_f block)
{
    size_t n;
    const unsigned char *iv = ivec;

    assert(in && out && key && ivec);

#if !defined(OPENSSL_SMALL_FOOTPRINT)
    if (STRICT_ALIGNMENT &&
        ((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) {
        while (len>=16) {
            for(n=0; n<16; ++n)
                out[n] = in[n] ^ iv[n];
            (*block)(out, out, key);
            iv = out;
            len -= 16;
            in  += 16;
            out += 16;
        }
    } else {
        while (len>=16) {
            for(n=0; n<16; n+=sizeof(size_t))
                *(size_t*)(out+n) =
                *(size_t*)(in+n) ^ *(size_t*)(iv+n);
            (*block)(out, out, key);
            iv = out;
            len -= 16;
            in  += 16;
            out += 16;
        }
    }
#endif
    while (len) {
        for(n=0; n<16 && n<len; ++n)
            out[n] = in[n] ^ iv[n];
        for(; n<16; ++n)
            out[n] = iv[n];
        (*block)(out, out, key);
        iv = out;
        if (len<=16) break;
        len -= 16;
        in  += 16;
        out += 16;
    }
    memcpy(ivec,iv,16);
}

void CRYPTO_cbc128_decrypt(const unsigned char *in, unsigned char *out,
            size_t len, const void *key,
            unsigned char ivec[16], block128_f block)
{
    size_t n;
    union { size_t align; unsigned char c[16]; } tmp;

    assert(in && out && key && ivec);

#if !defined(OPENSSL_SMALL_FOOTPRINT)
    if (in != out) {
        const unsigned char *iv = ivec;

        if (STRICT_ALIGNMENT &&
            ((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) {
            while (len>=16) {
                (*block)(in, out, key);
                for(n=0; n<16; ++n)
                    out[n] ^= iv[n];
                iv = in;
                len -= 16;
                in  += 16;
                out += 16;
            }
        }
        else {
            while (len>=16) {
                (*block)(in, out, key);
                for(n=0; n<16; n+=sizeof(size_t))
                    *(size_t *)(out+n) ^= *(size_t *)(iv+n);
                iv = in;
                len -= 16;
                in  += 16;
                out += 16;
            }
        }
        memcpy(ivec,iv,16);
    } else {
        if (STRICT_ALIGNMENT &&
            ((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) {
            unsigned char c;
            while (len>=16) {
                (*block)(in, tmp.c, key);
                for(n=0; n<16; ++n) {
                    c = in[n];
                    out[n] = tmp.c[n] ^ ivec[n];
                    ivec[n] = c;
                }
                len -= 16;
                in  += 16;
                out += 16;
            }
        }
        else {
            size_t c;
            while (len>=16) {
                (*block)(in, tmp.c, key);
                for(n=0; n<16; n+=sizeof(size_t)) {
                    c = *(size_t *)(in+n);
                    *(size_t *)(out+n) =
                    *(size_t *)(tmp.c+n) ^ *(size_t *)(ivec+n);
                    *(size_t *)(ivec+n) = c;
                }
                len -= 16;
                in  += 16;
                out += 16;
            }
        }
    }
#endif
    while (len) {
        unsigned char c;
        (*block)(in, tmp.c, key);
        for(n=0; n<16 && n<len; ++n) {
            c = in[n];
            out[n] = tmp.c[n] ^ ivec[n];
            ivec[n] = c;
        }
        if (len<=16) {
            for (; n<16; ++n)
                ivec[n] = in[n];
            break;
        }
        len -= 16;
        in  += 16;
        out += 16;
    }
}