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Store set lenghts in ccm context.

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Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
This commit is contained in:
Mateusz Starzyk 2021-07-06 12:45:11 +02:00
parent 88c4d624f8
commit eb2ca96d69
2 changed files with 20 additions and 30 deletions
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5
include/mbedtls/ccm.h
View File

@ -81,7 +81,10 @@ typedef struct mbedtls_ccm_context
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 */
size_t MBEDTLS_PRIVATE(plaintext_len); /*!< The counter buffer */
size_t MBEDTLS_PRIVATE(plaintext_len); /*!< Total plaintext length */
size_t MBEDTLS_PRIVATE(add_len); /*!< Total authentication data length */
size_t MBEDTLS_PRIVATE(tag_len); /*!< Total tag length */
size_t MBEDTLS_PRIVATE(processed); /*!< How many bytes of input data were processed (chunked input) */
int MBEDTLS_PRIVATE(mode); /*!< The operation to perform:
#MBEDTLS_CCM_ENCRYPT or
#MBEDTLS_CCM_DECRYPT or

45
library/ccm.c
View File

@ -172,10 +172,20 @@ static int mbedtls_ccm_calculate_first_block(mbedtls_ccm_context *ctx)
/*
* First block B_0:
* 0 .. 0 flags - set by: mbedtls_ccm_starts() and mbedtls_ccm_set_lenghts()
* 0 .. 0 flags
* 1 .. iv_len nonce (aka iv) - set by: mbedtls_ccm_starts()
* iv_len+1 .. 15 length - set by: mbedtls_ccm_calculate_first_block()
* iv_len+1 .. 15 length
*
* With flags as (bits):
* 7 0
* 6 add present?
* 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;
for( i = 0, len_left = ctx->plaintext_len; i < ctx->q; i++, len_left >>= 8 )
ctx->b[15-i] = (unsigned char)( len_left & 0xFF );
@ -225,19 +235,8 @@ int mbedtls_ccm_starts( mbedtls_ccm_context *ctx,
ctx->ctr[15] = 1;
/*
* First block B_0:
* 0 .. 0 flags - set by: mbedtls_ccm_starts() and mbedtls_ccm_set_lenghts()
* 1 .. iv_len nonce (aka iv) - set by: mbedtls_ccm_starts()
* iv_len+1 .. 15 length - set by: mbedtls_ccm_calculate_first_block()
*
* With flags as (bits):
* 7 0
* 6 add present? - set by: mbedtls_ccm_set_lengths()
* 5 .. 3 (t - 2) / 2 - set by: mbedtls_ccm_set_lengths()
* 2 .. 0 q - 1 - set by: mbedtls_ccm_starts()
* See mbedtls_ccm_calculate_first_block() for B block layout description
*/
ctx->b[0] |= ctx->q - 1;
memcpy( ctx->b + 1, iv, iv_len );
ctx->state |= CCM_STATE__STARTED;
@ -267,22 +266,10 @@ int mbedtls_ccm_set_lengths( mbedtls_ccm_context *ctx,
mbedtls_ccm_clear_state(ctx);
}
/*
* First block B_0:
* 0 .. 0 flags - set by: mbedtls_ccm_starts() and mbedtls_ccm_set_lenghts()
* 1 .. iv_len nonce (aka iv) - set by: mbedtls_ccm_starts()
* iv_len+1 .. 15 length - set by: mbedtls_ccm_calculate_first_block()
*
* With flags as (bits):
* 7 0
* 6 add present? - set by: mbedtls_ccm_set_lengths()
* 5 .. 3 (t - 2) / 2 - set by: mbedtls_ccm_set_lengths()
* 2 .. 0 q - 1 - set by: mbedtls_ccm_starts()
*/
ctx->b[0] |= ( total_ad_len > 0 ) << 6;
ctx->b[0] |= ( ( tag_len - 2 ) / 2 ) << 3;
ctx->plaintext_len = plaintext_len;
ctx->add_len = total_ad_len;
ctx->tag_len = tag_len;
ctx->processed = 0;
ctx->state |= CCM_STATE__LENGHTS_SET;
return mbedtls_ccm_calculate_first_block(ctx);