return_type aes_decrypt( const unsigned char in[N_BLOCK], unsigned char out[N_BLOCK], const aes_context ctx[1] )
{
if( ctx->rnd )
{
uint_8t s1[N_BLOCK], r;
copy_and_key( s1, in, ctx->ksch + ctx->rnd * N_BLOCK );
inv_shift_sub_rows( s1 );
for( r = ctx->rnd ; --r ; )
#if defined( VERSION_1 )
{
add_round_key( s1, ctx->ksch + r * N_BLOCK );
inv_mix_sub_columns( s1 );
}
#else
{ uint_8t s2[N_BLOCK];
copy_and_key( s2, s1, ctx->ksch + r * N_BLOCK );
inv_mix_sub_columns( s1, s2 );
}
#endif
copy_and_key( out, s1, ctx->ksch );
}
else
return (return_type) -1;
return 0;
}
void aes_decrypt_128( const unsigned char in[N_BLOCK], unsigned char out[N_BLOCK],
const unsigned char key[N_BLOCK], unsigned char o_key[N_BLOCK] )
{
uint_8t s1[N_BLOCK], r, rc = 0x6c;
if(o_key != key)
block16_copy( o_key, key );
copy_and_key( s1, in, o_key );
inv_shift_sub_rows( s1 );
for( r = 10 ; --r ; )
#if defined( VERSION_1 )
{
update_decrypt_key_128( o_key, &rc );
add_round_key( s1, o_key );
inv_mix_sub_columns( s1 );
}
#else
{ uint_8t s2[N_BLOCK];
update_decrypt_key_128( o_key, &rc );
copy_and_key( s2, s1, o_key );
inv_mix_sub_columns( s1, s2 );
}
#endif
update_decrypt_key_128( o_key, &rc );
copy_and_key( out, s1, o_key );
}
/* Decrypt a single block of 16 bytes with 'on the fly'
256 bit keying
*/
void aes_decrypt_256( const unsigned char in[N_BLOCK], unsigned char out[N_BLOCK],
const unsigned char key[2 * N_BLOCK], unsigned char o_key[2 * N_BLOCK] )
{
uint_8t s1[N_BLOCK], r, rc = 0x80;
if(o_key != key)
{
block16_copy( o_key, key );
block16_copy( o_key + 16, key + 16 );
}
copy_and_key( s1, in, o_key );
inv_shift_sub_rows( s1 );
for( r = 14 ; --r ; )
#if defined( VERSION_1 )
{
if( ( r & 1 ) )
{
update_decrypt_key_256( o_key, &rc );
add_round_key( s1, o_key + 16 );
}
else
add_round_key( s1, o_key );
inv_mix_sub_columns( s1 );
}
#else
{ uint_8t s2[N_BLOCK];
if( ( r & 1 ) )
{
update_decrypt_key_256( o_key, &rc );
copy_and_key( s2, s1, o_key + 16 );
}
else
copy_and_key( s2, s1, o_key );
inv_mix_sub_columns( s1, s2 );
}
#endif
copy_and_key( out, s1, o_key );
}
byte AES::decrypt (byte cipher [N_BLOCK], byte plain [N_BLOCK])
{
if (round) {
byte s1 [N_BLOCK] ;
copy_and_key (s1, cipher, (byte*) (key_sched + round * N_BLOCK)) ;
inv_shift_sub_rows (s1) ;
for (byte r = round ; --r ; ) {
byte s2 [N_BLOCK] ;
copy_and_key (s2, s1, (byte*) (key_sched + r * N_BLOCK)) ;
inv_mix_sub_columns (s1, s2) ;
}
copy_and_key (plain, s1, (byte*) (key_sched)) ;
} else {
return AES_FAILURE ;
}
return AES_SUCCESS ;
}
/**
* Decrypts a single block of 16 bytes
* @param in Buffer holding the input data
* @param out Buffer holding the output data
* @param ctx AES context
* @return Status from the result
*/
aes_result AES::aes_decrypt( const unsigned char in[N_BLOCK], unsigned char out[N_BLOCK], const aes_context ctx[1] )
{
if( ctx->rnd )
{
uint_8t s1[N_BLOCK], r;
copy_and_key( s1, in, ctx->ksch + ctx->rnd * N_BLOCK );
inv_shift_sub_rows( s1 );
for( r = ctx->rnd ; --r ; )
{
add_round_key( s1, ctx->ksch + r * N_BLOCK );
inv_mix_sub_columns( s1 );
}
copy_and_key( out, s1, ctx->ksch );
}
else
return -1;
return 0;
}