aes_modes.c

AES高级加密标准的C代码

/*
 ---------------------------------------------------------------------------
 Copyright (c) 2003, Dr Brian Gladman, Worcester, UK.   All rights reserved.

 LICENSE TERMS

 The free distribution and use of this software in both source and binary
 form is allowed (with or without changes) provided that:

   1. distributions of this source code include the above copyright
      notice, this list of conditions and the following disclaimer;

   2. distributions in binary form include the above copyright
      notice, this list of conditions and the following disclaimer
      in the documentation and/or other associated materials;

   3. the copyright holder's name is not used to endorse products
      built using this software without specific written permission.

 ALTERNATIVELY, provided that this notice is retained in full, this product
 may be distributed under the terms of the GNU General Public License (GPL),
 in which case the provisions of the GPL apply INSTEAD OF those given above.

 DISCLAIMER

 This software is provided 'as is' with no explicit or implied warranties
 in respect of its properties, including, but not limited to, correctness
 and/or fitness for purpose.
 ---------------------------------------------------------------------------
 Issue 01/08/2005

 These subroutines implement multiple block AES modes for ECB, CBC, CFB,
 OFB and CTR encryption. The code relies on unsafe pointer manipulation on
 the assumption that the lowest 4 bits of a pointer can be used to assess
 memory alignment.

*/

#include <memory.h>
#include <assert.h>

#include "aesopt.h"

#if defined(__cplusplus)
extern "C"
{
#endif

#ifdef _MSC_VER
#pragma intrinsic(memcpy)
#define in_line __inline
#else
#define in_line
#endif

#define BFR_BLOCKS      8

/* These values are used to detect long word alignment in order to */
/* speed up some buffer operations. This facility may not work on  */
/* some machines so this define can be commented out if necessary  */

#define FAST_BUFFER_OPERATIONS

#pragma warning( disable : 4311 4312 )

#define lp08(x)            ((uint_8t*)(x))
#define lp32(x)            ((uint_32t*)(x))
#define align_from_04(x)   ((unsigned long)(x) & 3)

aes_rval aes_mode_reset(aes_encrypt_ctx ctx[1])
{
    ctx->inf.b[2] = 0;
    return EXIT_SUCCESS;
}

aes_rval aes_ecb_encrypt(const unsigned char *ibuf, unsigned char *obuf,
                    int len, const aes_encrypt_ctx ctx[1])
{   int nb = len >> 4;

    if(len & (AES_BLOCK_SIZE - 1))
        return EXIT_FAILURE;

    while(nb--)
    {
        aes_encrypt(ibuf, obuf, ctx);
        ibuf += AES_BLOCK_SIZE;
        obuf += AES_BLOCK_SIZE;
    }

    return EXIT_SUCCESS;
}

aes_rval aes_ecb_decrypt(const unsigned char *ibuf, unsigned char *obuf,
                    int len, const aes_decrypt_ctx ctx[1])
{   int nb = len >> 4;

    if(len & (AES_BLOCK_SIZE - 1))
        return EXIT_FAILURE;

    while(nb--)
    {
        aes_decrypt(ibuf, obuf, ctx);
        ibuf += AES_BLOCK_SIZE;
        obuf += AES_BLOCK_SIZE;
    }

    return EXIT_SUCCESS;
}

aes_rval aes_cbc_encrypt(const unsigned char *ibuf, unsigned char *obuf,
                    int len, unsigned char *iv, const aes_encrypt_ctx ctx[1])
{   int nb = len >> 4;

    if(len & (AES_BLOCK_SIZE - 1))
        return EXIT_FAILURE;

#ifdef FAST_BUFFER_OPERATIONS
    if(!align_from_04(ibuf) && !align_from_04(iv))
        while(nb--)
        {
            lp32(iv)[0] ^= lp32(ibuf)[0];
            lp32(iv)[1] ^= lp32(ibuf)[1];
            lp32(iv)[2] ^= lp32(ibuf)[2];
            lp32(iv)[3] ^= lp32(ibuf)[3];
            aes_encrypt(iv, iv, ctx);
            memcpy(obuf, iv, AES_BLOCK_SIZE);
            ibuf += AES_BLOCK_SIZE;
            obuf += AES_BLOCK_SIZE;
        }
    else
#endif
        while(nb--)
        {
            iv[ 0] ^= ibuf[ 0]; iv[ 1] ^= ibuf[ 1];
            iv[ 2] ^= ibuf[ 2]; iv[ 3] ^= ibuf[ 3];
            iv[ 4] ^= ibuf[ 4]; iv[ 5] ^= ibuf[ 5];
            iv[ 6] ^= ibuf[ 6]; iv[ 7] ^= ibuf[ 7];
            iv[ 8] ^= ibuf[ 8]; iv[ 9] ^= ibuf[ 9];
            iv[10] ^= ibuf[10]; iv[11] ^= ibuf[11];
            iv[12] ^= ibuf[12]; iv[13] ^= ibuf[13];
            iv[14] ^= ibuf[14]; iv[15] ^= ibuf[15];
            aes_encrypt(iv, iv, ctx);
            memcpy(obuf, iv, AES_BLOCK_SIZE);
            ibuf += AES_BLOCK_SIZE;
            obuf += AES_BLOCK_SIZE;
        }

    return EXIT_SUCCESS;
}

aes_rval aes_cbc_decrypt(const unsigned char *ibuf, unsigned char *obuf,
                    int len, unsigned char *iv, const aes_decrypt_ctx ctx[1])
{   unsigned char tmp[AES_BLOCK_SIZE];
    int nb = len >> 4;

    if(len & (AES_BLOCK_SIZE - 1))
        return EXIT_FAILURE;

#ifdef FAST_BUFFER_OPERATIONS
    if(!align_from_04(obuf) && !align_from_04(iv))
        while(nb--)
        {
            memcpy(tmp, ibuf, AES_BLOCK_SIZE);
            aes_decrypt(ibuf, obuf, ctx);
            lp32(obuf)[0] ^= lp32(iv)[0];
            lp32(obuf)[1] ^= lp32(iv)[1];
            lp32(obuf)[2] ^= lp32(iv)[2];
            lp32(obuf)[3] ^= lp32(iv)[3];
            memcpy(iv, tmp, AES_BLOCK_SIZE);
            ibuf += AES_BLOCK_SIZE;
            obuf += AES_BLOCK_SIZE;
        }
    else
#endif
        while(nb--)
        {
            memcpy(tmp, ibuf, AES_BLOCK_SIZE);
            aes_decrypt(ibuf, obuf, ctx);
            obuf[ 0] ^= iv[ 0]; obuf[ 1] ^= iv[ 1];
            obuf[ 2] ^= iv[ 2]; obuf[ 3] ^= iv[ 3];
            obuf[ 4] ^= iv[ 4]; obuf[ 5] ^= iv[ 5];
            obuf[ 6] ^= iv[ 6]; obuf[ 7] ^= iv[ 7];
            obuf[ 8] ^= iv[ 8]; obuf[ 9] ^= iv[ 9];
            obuf[10] ^= iv[10]; obuf[11] ^= iv[11];
            obuf[12] ^= iv[12]; obuf[13] ^= iv[13];
            obuf[14] ^= iv[14]; obuf[15] ^= iv[15];
            memcpy(iv, tmp, AES_BLOCK_SIZE);
            ibuf += AES_BLOCK_SIZE;
            obuf += AES_BLOCK_SIZE;
        }

    return EXIT_SUCCESS;
}

aes_rval aes_cfb_encrypt(const unsigned char *ibuf, unsigned char *obuf,
                    int len, unsigned char *iv, aes_encrypt_ctx ctx[1])
{   int cnt = 0, b_pos = (int)ctx->inf.b[2], nb;

    if(b_pos)           /* complete any partial block   */
    {
        while(b_pos < AES_BLOCK_SIZE && cnt < len)
            *obuf++ = iv[b_pos++] ^= *ibuf++, cnt++;

        b_pos = (b_pos == AES_BLOCK_SIZE ? 0 : b_pos);
    }

    if(nb = (len - cnt) >> 4)   /* process whole blocks */
    {
#ifdef FAST_BUFFER_OPERATIONS
        if(!align_from_04(ibuf) && !align_from_04(obuf) && !align_from_04(iv))
            while(cnt + AES_BLOCK_SIZE <= len)
            {
                assert(b_pos == 0);
                aes_encrypt(iv, iv, ctx);
                lp32(obuf)[0] = lp32(iv)[0] ^= lp32(ibuf)[0];
                lp32(obuf)[1] = lp32(iv)[1] ^= lp32(ibuf)[1];
                lp32(obuf)[2] = lp32(iv)[2] ^= lp32(ibuf)[2];
                lp32(obuf)[3] = lp32(iv)[3] ^= lp32(ibuf)[3];
                ibuf += AES_BLOCK_SIZE;
                obuf += AES_BLOCK_SIZE;
                cnt  += AES_BLOCK_SIZE;
            }
        else
#endif
            while(cnt + AES_BLOCK_SIZE <= len)
            {
                assert(b_pos == 0);
                aes_encrypt(iv, iv, ctx);
                obuf[ 0] = iv[ 0] ^= ibuf[ 0]; obuf[ 1] = iv[ 1] ^= ibuf[ 1];
                obuf[ 2] = iv[ 2] ^= ibuf[ 2]; obuf[ 3] = iv[ 3] ^= ibuf[ 3];
                obuf[ 4] = iv[ 4] ^= ibuf[ 4]; obuf[ 5] = iv[ 5] ^= ibuf[ 5];
                obuf[ 6] = iv[ 6] ^= ibuf[ 6]; obuf[ 7] = iv[ 7] ^= ibuf[ 7];
                obuf[ 8] = iv[ 8] ^= ibuf[ 8]; obuf[ 9] = iv[ 9] ^= ibuf[ 9];
                obuf[10] = iv[10] ^= ibuf[10]; obuf[11] = iv[11] ^= ibuf[11];
                obuf[12] = iv[12] ^= ibuf[12]; obuf[13] = iv[13] ^= ibuf[13];
                obuf[14] = iv[14] ^= ibuf[14]; obuf[15] = iv[15] ^= ibuf[15];
                ibuf += AES_BLOCK_SIZE;