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aeskey.c

/*
 -------------------------------------------------------------------------
 Copyright (c) 2001, Dr Brian Gladman <brg@gladman.me.uk>, 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. 

 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 fitness for purpose.
 -------------------------------------------------------------------------
 Issue Date: 29/07/2002

 This file contains the code for implementing the key schedule for AES 
 (Rijndael) for block and key sizes of 16, 24, and 32 bytes.
*/

#include "aesopt.h"

#if defined(BLOCK_SIZE) && (BLOCK_SIZE & 7)
#error An illegal block size has been specified.
#endif  

/* Subroutine to set the block size (if variable) in bytes, legal
   values being 16, 24 and 32. 
*/

#if !defined(BLOCK_SIZE)

aes_rval aes_blk_len(unsigned int blen, aes_ctx cx[1])
{
#if !defined(FIXED_TABLES)
    if(!tab_init) gen_tabs();
#endif

    if((blen & 7) || blen < 16 || blen > 32) 
    {     
        cx->n_blk = 0; return aes_bad;
    }

    cx->n_blk = blen;
    return aes_good;
}

#endif

/* Initialise the key schedule from the user supplied key. The key
   length is now specified in bytes - 16, 24 or 32 as appropriate.
   This corresponds to bit lengths of 128, 192 and 256 bits, and
   to Nk values of 4, 6 and 8 respectively.

   The following macros implement a single cycle in the key 
   schedule generation process. The number of cycles needed 
   for each cx->n_col and nk value is:
 
    nk =             4  5  6  7  8
    ------------------------------
    cx->n_col = 4   10  9  8  7  7
    cx->n_col = 5   14 11 10  9  9
    cx->n_col = 6   19 15 12 11 11
    cx->n_col = 7   21 19 16 13 14
    cx->n_col = 8   29 23 19 17 14
*/

#define ke4(k,i) \
{   k[4*(i)+4] = ss[0] ^= ls_box(ss[3],3) ^ rcon_tab[i]; k[4*(i)+5] = ss[1] ^= ss[0]; \
    k[4*(i)+6] = ss[2] ^= ss[1]; k[4*(i)+7] = ss[3] ^= ss[2]; \
}
#define kel4(k,i) \
{   k[4*(i)+4] = ss[0] ^= ls_box(ss[3],3) ^ rcon_tab[i]; k[4*(i)+5] = ss[1] ^= ss[0]; \
    k[4*(i)+6] = ss[2] ^= ss[1]; k[4*(i)+7] = ss[3] ^= ss[2]; \
}

#define ke6(k,i) \
{   k[6*(i)+ 6] = ss[0] ^= ls_box(ss[5],3) ^ rcon_tab[i]; k[6*(i)+ 7] = ss[1] ^= ss[0]; \
    k[6*(i)+ 8] = ss[2] ^= ss[1]; k[6*(i)+ 9] = ss[3] ^= ss[2]; \
    k[6*(i)+10] = ss[4] ^= ss[3]; k[6*(i)+11] = ss[5] ^= ss[4]; \
}
#define kel6(k,i) \
{   k[6*(i)+ 6] = ss[0] ^= ls_box(ss[5],3) ^ rcon_tab[i]; k[6*(i)+ 7] = ss[1] ^= ss[0]; \
    k[6*(i)+ 8] = ss[2] ^= ss[1]; k[6*(i)+ 9] = ss[3] ^= ss[2]; \
}

#define ke8(k,i) \
{   k[8*(i)+ 8] = ss[0] ^= ls_box(ss[7],3) ^ rcon_tab[i]; k[8*(i)+ 9] = ss[1] ^= ss[0]; \
    k[8*(i)+10] = ss[2] ^= ss[1]; k[8*(i)+11] = ss[3] ^= ss[2]; \
    k[8*(i)+12] = ss[4] ^= ls_box(ss[3],0); k[8*(i)+13] = ss[5] ^= ss[4]; \
    k[8*(i)+14] = ss[6] ^= ss[5]; k[8*(i)+15] = ss[7] ^= ss[6]; \
}
#define kel8(k,i) \
{   k[8*(i)+ 8] = ss[0] ^= ls_box(ss[7],3) ^ rcon_tab[i]; k[8*(i)+ 9] = ss[1] ^= ss[0]; \
    k[8*(i)+10] = ss[2] ^= ss[1]; k[8*(i)+11] = ss[3] ^= ss[2]; \
}

#if defined(ENCRYPTION_KEY_SCHEDULE)

aes_rval aes_enc_key(const unsigned char in_key[], unsigned int klen, aes_ctx cx[1])
{   aes_32t    ss[8]; 

#if !defined(FIXED_TABLES)
    if(!tab_init) gen_tabs();
#endif

#if !defined(BLOCK_SIZE)
    if(!cx->n_blk) cx->n_blk = 16;
#else
    cx->n_blk = BLOCK_SIZE;
#endif
    
    cx->n_blk = (cx->n_blk & ~3) | 1;

    cx->k_sch[0] = ss[0] = word_in(in_key     );
    cx->k_sch[1] = ss[1] = word_in(in_key +  4);
    cx->k_sch[2] = ss[2] = word_in(in_key +  8);
    cx->k_sch[3] = ss[3] = word_in(in_key + 12);

#if (BLOCK_SIZE == 16) && (ENC_UNROLL != NONE)

    switch(klen)
    {
    case 16:    ke4(cx->k_sch, 0); ke4(cx->k_sch, 1); 
                ke4(cx->k_sch, 2); ke4(cx->k_sch, 3);
                ke4(cx->k_sch, 4); ke4(cx->k_sch, 5); 
                ke4(cx->k_sch, 6); ke4(cx->k_sch, 7);
                ke4(cx->k_sch, 8); kel4(cx->k_sch, 9); 
                cx->n_rnd = 10; break;
    case 24:    cx->k_sch[4] = ss[4] = word_in(in_key + 16);
                cx->k_sch[5] = ss[5] = word_in(in_key + 20);
                ke6(cx->k_sch, 0); ke6(cx->k_sch, 1); 
                ke6(cx->k_sch, 2); ke6(cx->k_sch, 3);
                ke6(cx->k_sch, 4); ke6(cx->k_sch, 5); 
                ke6(cx->k_sch, 6); kel6(cx->k_sch, 7); 
                cx->n_rnd = 12; break;
    case 32:    cx->k_sch[4] = ss[4] = word_in(in_key + 16);
                cx->k_sch[5] = ss[5] = word_in(in_key + 20);
                cx->k_sch[6] = ss[6] = word_in(in_key + 24);
                cx->k_sch[7] = ss[7] = word_in(in_key + 28);
                ke8(cx->k_sch, 0); ke8(cx->k_sch, 1); 
                ke8(cx->k_sch, 2); ke8(cx->k_sch, 3);
                ke8(cx->k_sch, 4); ke8(cx->k_sch, 5); 
                kel8(cx->k_sch, 6); 
                cx->n_rnd = 14; break;
    default:    cx->n_rnd = 0; return aes_bad; 
    }
#else
    {   aes_32t i, l;
        cx->n_rnd = ((klen >> 2) > nc ? (klen >> 2) : nc) + 6;
        l = (nc * cx->n_rnd + nc - 1) / (klen >> 2);

        switch(klen)
        {
        case 16:    for(i = 0; i < l; ++i)
                        ke4(cx->k_sch, i);
                    break;
        case 24:    cx->k_sch[4] = ss[4] = word_in(in_key + 16);
                    cx->k_sch[5] = ss[5] = word_in(in_key + 20);
                    for(i = 0; i < l; ++i)
                        ke6(cx->k_sch, i);
                    break;
        case 32:    cx->k_sch[4] = ss[4] = word_in(in_key + 16);
                    cx->k_sch[5] = ss[5] = word_in(in_key + 20);
                    cx->k_sch[6] = ss[6] = word_in(in_key + 24);
                    cx->k_sch[7] = ss[7] = word_in(in_key + 28);
                    for(i = 0; i < l; ++i)
                        ke8(cx->k_sch,  i);
                    break;
        default:    cx->n_rnd = 0; return aes_bad; 
        }
    }
#endif

    return aes_good;
}

#endif

#if defined(DECRYPTION_KEY_SCHEDULE)

#if (DEC_ROUND != NO_TABLES)
#define d_vars  dec_imvars
#define ff(x)   inv_mcol(x)
#else
#define ff(x)   (x)
#define d_vars
#endif

#if 1
#define kdf4(k,i) \
{   ss[0] = ss[0] ^ ss[2] ^ ss[1] ^ ss[3]; ss[1] = ss[1] ^ ss[3]; ss[2] = ss[2] ^ ss[3]; ss[3] = ss[3]; \
    ss[4] = ls_box(ss[(i+3) % 4], 3) ^ rcon_tab[i]; ss[i % 4] ^= ss[4]; \
    ss[4] ^= k[4*(i)];   k[4*(i)+4] = ff(ss[4]); ss[4] ^= k[4*(i)+1]; k[4*(i)+5] = ff(ss[4]); \
    ss[4] ^= k[4*(i)+2]; k[4*(i)+6] = ff(ss[4]); ss[4] ^= k[4*(i)+3]; k[4*(i)+7] = ff(ss[4]); \
}
#define kd4(k,i) \
{   ss[4] = ls_box(ss[(i+3) % 4], 3) ^ rcon_tab[i]; ss[i % 4] ^= ss[4]; ss[4] = ff(ss[4]); \
    k[4*(i)+4] = ss[4] ^= k[4*(i)]; k[4*(i)+5] = ss[4] ^= k[4*(i)+1]; \
    k[4*(i)+6] = ss[4] ^= k[4*(i)+2]; k[4*(i)+7] = ss[4] ^= k[4*(i)+3]; \
}
#define kdl4(k,i) \
{   ss[4] = ls_box(ss[(i+3) % 4], 3) ^ rcon_tab[i]; ss[i % 4] ^= ss[4]; \
    k[4*(i)+4] = (ss[0] ^= ss[1]) ^ ss[2] ^ ss[3]; k[4*(i)+5] = ss[1] ^ ss[3]; \
    k[4*(i)+6] = ss[0]; k[4*(i)+7] = ss[1]; \
}
#else
#define kdf4(k,i) \
{   ss[0] ^= ls_box(ss[3],3) ^ rcon_tab[i]; k[4*(i)+ 4] = ff(ss[0]); ss[1] ^= ss[0]; k[4*(i)+ 5] = ff(ss[1]); \
    ss[2] ^= ss[1]; k[4*(i)+ 6] = ff(ss[2]); ss[3] ^= ss[2]; k[4*(i)+ 7] = ff(ss[3]); \
}
#define kd4(k,i) \
{   ss[4] = ls_box(ss[3],3) ^ rcon_tab[i]; \
    ss[0] ^= ss[4]; ss[4] = ff(ss[4]); k[4*(i)+ 4] = ss[4] ^= k[4*(i)]; \
    ss[1] ^= ss[0]; k[4*(i)+ 5] = ss[4] ^= k[4*(i)+ 1]; \
    ss[2] ^= ss[1]; k[4*(i)+ 6] = ss[4] ^= k[4*(i)+ 2]; \
    ss[3] ^= ss[2]; k[4*(i)+ 7] = ss[4] ^= k[4*(i)+ 3]; \
}
#define kdl4(k,i) \
{   ss[0] ^= ls_box(ss[3],3) ^ rcon_tab[i]; k[4*(i)+ 4] = ss[0]; ss[1] ^= ss[0]; k[4*(i)+ 5] = ss[1]; \
    ss[2] ^= ss[1]; k[4*(i)+ 6] = ss[2]; ss[3] ^= ss[2]; k[4*(i)+ 7] = ss[3]; \
}
#endif

#define kdf6(k,i) \
{   ss[0] ^= ls_box(ss[5],3) ^ rcon_tab[i]; k[6*(i)+ 6] = ff(ss[0]); ss[1] ^= ss[0]; k[6*(i)+ 7] = ff(ss[1]); \
    ss[2] ^= ss[1]; k[6*(i)+ 8] = ff(ss[2]); ss[3] ^= ss[2]; k[6*(i)+ 9] = ff(ss[3]); \
    ss[4] ^= ss[3]; k[6*(i)+10] = ff(ss[4]); ss[5] ^= ss[4]; k[6*(i)+11] = ff(ss[5]); \
}
#define kd6(k,i) \
{   ss[6] = ls_box(ss[5],3) ^ rcon_tab[i]; \
    ss[0] ^= ss[6]; ss[6] = ff(ss[6]); k[6*(i)+ 6] = ss[6] ^= k[6*(i)]; \
    ss[1] ^= ss[0]; k[6*(i)+ 7] = ss[6] ^= k[6*(i)+ 1]; \
    ss[2] ^= ss[1]; k[6*(i)+ 8] = ss[6] ^= k[6*(i)+ 2]; \
    ss[3] ^= ss[2]; k[6*(i)+ 9] = ss[6] ^= k[6*(i)+ 3]; \
    ss[4] ^= ss[3]; k[6*(i)+10] = ss[6] ^= k[6*(i)+ 4]; \
    ss[5] ^= ss[4]; k[6*(i)+11] = ss[6] ^= k[6*(i)+ 5]; \
}
#define kdl6(k,i) \
{   ss[0] ^= ls_box(ss[5],3) ^ rcon_tab[i]; k[6*(i)+ 6] = ss[0]; ss[1] ^= ss[0]; k[6*(i)+ 7] = ss[1]; \
    ss[2] ^= ss[1]; k[6*(i)+ 8] = ss[2]; ss[3] ^= ss[2]; k[6*(i)+ 9] = ss[3]; \
}

#define kdf8(k,i) \
{   ss[0] ^= ls_box(ss[7],3) ^ rcon_tab[i]; k[8*(i)+ 8] = ff(ss[0]); ss[1] ^= ss[0]; k[8*(i)+ 9] = ff(ss[1]); \
    ss[2] ^= ss[1]; k[8*(i)+10] = ff(ss[2]); ss[3] ^= ss[2]; k[8*(i)+11] = ff(ss[3]); \
    ss[4] ^= ls_box(ss[3],0); k[8*(i)+12] = ff(ss[4]); ss[5] ^= ss[4]; k[8*(i)+13] = ff(ss[5]); \
    ss[6] ^= ss[5]; k[8*(i)+14] = ff(ss[6]); ss[7] ^= ss[6]; k[8*(i)+15] = ff(ss[7]); \
}
#define kd8(k,i) \
{   aes_32t g = ls_box(ss[7],3) ^ rcon_tab[i]; \
    ss[0] ^= g; g = ff(g); k[8*(i)+ 8] = g ^= k[8*(i)]; \
    ss[1] ^= ss[0]; k[8*(i)+ 9] = g ^= k[8*(i)+ 1]; \
    ss[2] ^= ss[1]; k[8*(i)+10] = g ^= k[8*(i)+ 2]; \
    ss[3] ^= ss[2]; k[8*(i)+11] = g ^= k[8*(i)+ 3]; \
    g = ls_box(ss[3],0); \
    ss[4] ^= g; g = ff(g); k[8*(i)+12] = g ^= k[8*(i)+ 4]; \
    ss[5] ^= ss[4]; k[8*(i)+13] = g ^= k[8*(i)+ 5]; \
    ss[6] ^= ss[5]; k[8*(i)+14] = g ^= k[8*(i)+ 6]; \
    ss[7] ^= ss[6]; k[8*(i)+15] = g ^= k[8*(i)+ 7]; \
}
#define kdl8(k,i) \
{   ss[0] ^= ls_box(ss[7],3) ^ rcon_tab[i]; k[8*(i)+ 8] = ss[0]; ss[1] ^= ss[0]; k[8*(i)+ 9] = ss[1]; \
    ss[2] ^= ss[1]; k[8*(i)+10] = ss[2]; ss[3] ^= ss[2]; k[8*(i)+11] = ss[3]; \
}

aes_rval aes_dec_key(const unsigned char in_key[], unsigned int klen, aes_ctx cx[1])
{   aes_32t    ss[8]; 
    d_vars

#if !defined(FIXED_TABLES)
    if(!tab_init) gen_tabs();
#endif

#if !defined(BLOCK_SIZE)
    if(!cx->n_blk) cx->n_blk = 16;
#else
    cx->n_blk = BLOCK_SIZE;
#endif

    cx->n_blk = (cx->n_blk & ~3) | 2;

    cx->k_sch[0] = ss[0] = word_in(in_key     );
    cx->k_sch[1] = ss[1] = word_in(in_key +  4);
    cx->k_sch[2] = ss[2] = word_in(in_key +  8);
    cx->k_sch[3] = ss[3] = word_in(in_key + 12);

#if (BLOCK_SIZE == 16) && (DEC_UNROLL != NONE)

    switch(klen)
    {
    case 16:    kdf4(cx->k_sch, 0); kd4(cx->k_sch, 1); 
                kd4(cx->k_sch, 2); kd4(cx->k_sch, 3);
                kd4(cx->k_sch, 4); kd4(cx->k_sch, 5); 
                kd4(cx->k_sch, 6); kd4(cx->k_sch, 7);
                kd4(cx->k_sch, 8); kdl4(cx->k_sch, 9); 
                cx->n_rnd = 10; break;
    case 24:    cx->k_sch[4] = ff(ss[4] = word_in(in_key + 16));
                cx->k_sch[5] = ff(ss[5] = word_in(in_key + 20));
                kdf6(cx->k_sch, 0); kd6(cx->k_sch, 1); 
                kd6(cx->k_sch, 2); kd6(cx->k_sch, 3);
                kd6(cx->k_sch, 4); kd6(cx->k_sch, 5); 
                kd6(cx->k_sch, 6); kdl6(cx->k_sch, 7); 
                cx->n_rnd = 12; break;
    case 32:    cx->k_sch[4] = ff(ss[4] = word_in(in_key + 16));
                cx->k_sch[5] = ff(ss[5] = word_in(in_key + 20));
                cx->k_sch[6] = ff(ss[6] = word_in(in_key + 24));
                cx->k_sch[7] = ff(ss[7] = word_in(in_key + 28));
                kdf8(cx->k_sch, 0); kd8(cx->k_sch, 1); 
                kd8(cx->k_sch, 2); kd8(cx->k_sch, 3);
                kd8(cx->k_sch, 4); kd8(cx->k_sch, 5); 
                kdl8(cx->k_sch, 6); 
                cx->n_rnd = 14; break;
    default:    cx->n_rnd = 0; return aes_bad; 
    }
#else
    {   aes_32t i, l;
        cx->n_rnd = ((klen >> 2) > nc ? (klen >> 2) : nc) + 6;
        l = (nc * cx->n_rnd + nc - 1) / (klen >> 2);

        switch(klen)
        {
        case 16: 
                    for(i = 0; i < l; ++i)
                        ke4(cx->k_sch, i);
                    break;
        case 24:    cx->k_sch[4] = ss[4] = word_in(in_key + 16);
                    cx->k_sch[5] = ss[5] = word_in(in_key + 20);
                    for(i = 0; i < l; ++i)
                        ke6(cx->k_sch, i);
                    break;
        case 32:    cx->k_sch[4] = ss[4] = word_in(in_key + 16);
                    cx->k_sch[5] = ss[5] = word_in(in_key + 20);
                    cx->k_sch[6] = ss[6] = word_in(in_key + 24);
                    cx->k_sch[7] = ss[7] = word_in(in_key + 28);
                    for(i = 0; i < l; ++i)
                        ke8(cx->k_sch,  i);
                    break;
        default:    cx->n_rnd = 0; return aes_bad; 
        }
#if (DEC_ROUND != NO_TABLES)
        for(i = nc; i < nc * cx->n_rnd; ++i)
            cx->k_sch[i] = inv_mcol(cx->k_sch[i]);
#endif
    }
#endif

    return aes_good;
}

#endif

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