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Double perf for AES-XEX

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As seen from the first benchmark run, AES-XEX was running pourly (even
slower than AES-CBC). This commit doubles the performances of the
current implementation.
This commit is contained in:
Aorimn 2016-02-02 23:01:09 +01:00 committed by Jaeden Amero
parent daf7045372
commit 380162c34c
1 changed files with 21 additions and 12 deletions
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33
library/aes.c
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@ -999,36 +999,45 @@ int mbedtls_aes_crypt_xex( mbedtls_aes_context *crypt_ctx,
const unsigned char *input,
unsigned char *output )
{
int i;
unsigned char t_buf[16];
unsigned char scratch[16];
union xex_buf128 {
uint8_t u8[16];
uint64_t u64[2];
};
union xex_buf128 scratch;
union xex_buf128 t_buf;
union xex_buf128 *inbuf;
union xex_buf128 *outbuf;
inbuf = (union xex_buf128*)input;
outbuf = (union xex_buf128*)output;
if( length % 16 )
return( MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH );
mbedtls_aes_crypt_ecb( tweak_ctx, MBEDTLS_AES_ENCRYPT, iv, t_buf );
mbedtls_aes_crypt_ecb( tweak_ctx, MBEDTLS_AES_ENCRYPT, iv, t_buf.u8 );
goto first;
do
{
mbedtls_gf128mul_x_ble( t_buf, t_buf );
mbedtls_gf128mul_x_ble( t_buf.u8, t_buf.u8 );
first:
/* PP <- T xor P */
for( i = 0; i < 16; i++ )
scratch[i] = (unsigned char)( input[i] ^ t_buf[i] );
scratch.u64[0] = (uint64_t)( inbuf->u64[0] ^ t_buf.u64[0] );
scratch.u64[1] = (uint64_t)( inbuf->u64[1] ^ t_buf.u64[1] );
/* CC <- E(Key2,PP) */
mbedtls_aes_crypt_ecb( crypt_ctx, mode, scratch, output );
mbedtls_aes_crypt_ecb( crypt_ctx, mode, scratch.u8, outbuf->u8 );
/* C <- T xor CC */
for( i = 0; i < 16; i++ )
output[i] = (unsigned char)( output[i] ^ t_buf[i] );
outbuf->u64[0] = (uint64_t)( outbuf->u64[0] ^ t_buf.u64[0] );
outbuf->u64[1] = (uint64_t)( outbuf->u64[1] ^ t_buf.u64[1] );
input += 16;
output += 16;
inbuf += 1;
outbuf += 1;
length -= 16;
} while( length > 0 );