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Remove UPDATE_CBC macro and working b buffer.

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Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
This commit is contained in:
Mateusz Starzyk 2021-07-12 19:13:52 +02:00
parent 25a3dfe7dd
commit 663055f784
2 changed files with 33 additions and 42 deletions
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1
include/mbedtls/ccm.h
View File

@ -77,7 +77,6 @@ extern "C" {
typedef struct mbedtls_ccm_context
{
mbedtls_cipher_context_t MBEDTLS_PRIVATE(cipher_ctx); /*!< The cipher context used. */
unsigned char MBEDTLS_PRIVATE(b)[16]; /*!< The B working buffer */
unsigned char MBEDTLS_PRIVATE(y)[16]; /*!< The Y working buffer */
unsigned char MBEDTLS_PRIVATE(ctr)[16]; /*!< The counter buffer */
unsigned char MBEDTLS_PRIVATE(q); /*!< The Q working value */

74
library/ccm.c
View File

@ -106,22 +106,6 @@ void mbedtls_ccm_free( mbedtls_ccm_context *ctx )
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ccm_context ) );
}
/*
* Update the CBC-MAC state in y using a block in b
* (Always using b as the source helps the compiler optimise a bit better.)
*
* Macro results in smaller compiled code than static inline functions.
*/
#define UPDATE_CBC_MAC \
for( i = 0; i < 16; i++ ) \
ctx->y[i] ^= ctx->b[i]; \
\
if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen ) ) != 0 ) \
{ \
ctx->state |= CCM_STATE__ERROR; \
return( ret ); \
} \
#define CCM_STATE__CLEAR 0
#define CCM_STATE__STARTED 0x0001
#define CCM_STATE__LENGHTS_SET 0x0002
@ -155,7 +139,6 @@ static int mbedtls_ccm_crypt( mbedtls_ccm_context *ctx,
static void mbedtls_ccm_clear_state(mbedtls_ccm_context *ctx) {
ctx->state = CCM_STATE__CLEAR;
memset( ctx->b, 0, 16);
memset( ctx->y, 0, 16);
memset( ctx->ctr, 0, 16);
}
@ -177,7 +160,7 @@ static int mbedtls_ccm_calculate_first_block(mbedtls_ccm_context *ctx)
return( MBEDTLS_ERR_CCM_BAD_INPUT );
/*
* First block B_0:
* First block:
* 0 .. 0 flags
* 1 .. iv_len nonce (aka iv) - set by: mbedtls_ccm_starts()
* iv_len+1 .. 15 length
@ -188,12 +171,12 @@ static int mbedtls_ccm_calculate_first_block(mbedtls_ccm_context *ctx)
* 5 .. 3 (t - 2) / 2
* 2 .. 0 q - 1
*/
ctx->b[0] |= ( ctx->add_len > 0 ) << 6;
ctx->b[0] |= ( ( ctx->tag_len - 2 ) / 2 ) << 3;
ctx->b[0] |= ctx->q - 1;
ctx->y[0] |= ( ctx->add_len > 0 ) << 6;
ctx->y[0] |= ( ( ctx->tag_len - 2 ) / 2 ) << 3;
ctx->y[0] |= ctx->q - 1;
for( i = 0, len_left = ctx->plaintext_len; i < ctx->q; i++, len_left >>= 8 )
ctx->b[15-i] = (unsigned char)( len_left & 0xFF );
ctx->y[15-i] = (unsigned char)( len_left & 0xFF );
if( len_left > 0 )
{
@ -202,7 +185,11 @@ static int mbedtls_ccm_calculate_first_block(mbedtls_ccm_context *ctx)
}
/* Start CBC-MAC with first block*/
UPDATE_CBC_MAC;
if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen ) ) != 0 )
{
ctx->state |= CCM_STATE__ERROR;
return( ret );
}
return (0);
}
@ -248,9 +235,9 @@ int mbedtls_ccm_starts( mbedtls_ccm_context *ctx,
ctx->ctr[15] = 1;
/*
* See mbedtls_ccm_calculate_first_block() for B block layout description
* See mbedtls_ccm_calculate_first_block() for block layout description
*/
memcpy( ctx->b + 1, iv, iv_len );
memcpy( ctx->y + 1, iv, iv_len );
ctx->state |= CCM_STATE__STARTED;
return mbedtls_ccm_calculate_first_block(ctx);
@ -304,9 +291,8 @@ int mbedtls_ccm_update_ad( mbedtls_ccm_context *ctx,
{
if( ctx->processed == 0 )
{
memset( ctx->b, 0, 16 );
ctx->b[0] = (unsigned char)( ( ctx->add_len >> 8 ) & 0xFF );
ctx->b[1] = (unsigned char)( ( ctx->add_len ) & 0xFF );
ctx->y[0] ^= (unsigned char)( ( ctx->add_len >> 8 ) & 0xFF );
ctx->y[1] ^= (unsigned char)( ( ctx->add_len ) & 0xFF );
ctx->processed += 2;
}
@ -320,15 +306,20 @@ int mbedtls_ccm_update_ad( mbedtls_ccm_context *ctx,
if( use_len > add_len )
use_len = add_len;
memcpy( ctx->b + offset, add, use_len );
for( i = 0; i < use_len; i++ )
ctx->y[i + offset] ^= add[i];
ctx->processed += use_len;
add_len -= use_len;
add += use_len;
if( use_len + offset == 16 || ctx->processed - 2 == ctx->add_len )
{
UPDATE_CBC_MAC;
memset( ctx->b, 0, 16 );
if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen ) ) != 0 )
{
ctx->state |= CCM_STATE__ERROR;
return( ret );
}
}
}
}
@ -356,11 +347,6 @@ int mbedtls_ccm_update( mbedtls_ccm_context *ctx,
CCM_VALIDATE_RET( output_length != NULL );
*output_len = input_len;
if( ctx->processed == 0 )
{
memset( ctx->b, 0, 16 );
}
while ( input_len > 0 )
{
offset = ctx->processed % 16;
@ -371,16 +357,23 @@ int mbedtls_ccm_update( mbedtls_ccm_context *ctx,
use_len = input_len;
ctx->processed += use_len;
memcpy( ctx->b + offset, input, use_len );
if( ctx->mode == MBEDTLS_CCM_ENCRYPT || \
ctx->mode == MBEDTLS_CCM_STAR_ENCRYPT )
{
for( i = 0; i < use_len; i++ )
ctx->y[i + offset] ^= input[i];
if( use_len + offset == 16 || ctx->processed == ctx->plaintext_len )
{
UPDATE_CBC_MAC;
if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen ) ) != 0 )
{
ctx->state |= CCM_STATE__ERROR;
return( ret );
}
}
ret = mbedtls_ccm_crypt( ctx, offset, use_len, ctx->b + offset, output );
ret = mbedtls_ccm_crypt( ctx, offset, use_len, input, output );
if( ret != 0 )
return ret;
}
@ -388,7 +381,7 @@ int mbedtls_ccm_update( mbedtls_ccm_context *ctx,
if( ctx->mode == MBEDTLS_CCM_DECRYPT || \
ctx->mode == MBEDTLS_CCM_STAR_DECRYPT )
{
ret = mbedtls_ccm_crypt( ctx, offset, use_len, ctx->b + offset, output );
ret = mbedtls_ccm_crypt( ctx, offset, use_len, input, output );
if( ret != 0 )
return ret;
@ -410,7 +403,6 @@ int mbedtls_ccm_update( mbedtls_ccm_context *ctx,
for( i = 0; i < ctx->q; i++ )
if( ++(ctx->ctr)[15-i] != 0 )
break;
memset( ctx->b, 0, 16 );
}
input_len -= use_len;