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No CMAC minimum tag length is specified by NIST SP800-38B A

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Minor Typo Changes
This commit is contained in:
Brian Murray 2016-05-19 19:05:57 -07:00 committed by Simon Butcher
parent 617634e656
commit 87e4040bb9
2 changed files with 31 additions and 35 deletions
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8
include/mbedtls/cmac.h
View File

@ -84,8 +84,8 @@ void mbedtls_cmac_free( mbedtls_cmac_context *ctx );
* \param in_len length of the input data in bytes * \param in_len length of the input data in bytes
* \param tag buffer for holding the generated tag * \param tag buffer for holding the generated tag
* \param tag_len length of the tag to generate in bytes * \param tag_len length of the tag to generate in bytes
* Must be 4, 6, 8 if cipher block size is 64 * Must be 2, 4, 6, 8 if cipher block size is 64
* Must be 4, 6, 8 , 10, 12, 14 or 16 if cipher block size is 128 * Must be 2, 4, 6, 8, 10, 12, 14 or 16 if cipher block size is 128
* *
* \return 0 if successful * \return 0 if successful
*/ */
@ -101,8 +101,8 @@ int mbedtls_cmac_generate( mbedtls_cmac_context *ctx,
* \param in_len length of the input data in bytes * \param in_len length of the input data in bytes
* \param tag buffer holding the tag to verify * \param tag buffer holding the tag to verify
* \param tag_len length of the tag to verify in bytes * \param tag_len length of the tag to verify in bytes
* Must be 4, 6, 8 if cipher block size is 64 * Must be 2, 4, 6, 8 if cipher block size is 64
* Must be 4, 6, 8 , 10, 12, 14 or 16 if cipher block size is 128 * Must be 2, 4, 6, 8, 10, 12, 14 or 16 if cipher block size is 128
* \return 0 if successful and authenticated * \return 0 if successful and authenticated
* MBEDTLS_ERR_CMAC_VERIFY_FAILED if tag does not match * MBEDTLS_ERR_CMAC_VERIFY_FAILED if tag does not match
*/ */

10
library/cmac.c
View File

@ -62,7 +62,7 @@ void mbedtls_cmac_init( mbedtls_cmac_context *ctx )
/* /*
* Multiplication by u in the Galois field of GF(2^n) * Multiplication by u in the Galois field of GF(2^n)
* *
* As explained in the paper, this can computed: * As explained in the paper, this can be computed:
* If MSB(p) = 0, then p = (p << 1) * If MSB(p) = 0, then p = (p << 1)
* If MSB(p) = 1, then p = (p << 1) ^ R_n * If MSB(p) = 1, then p = (p << 1) ^ R_n
* with R_64 = 0x1B and R_128 = 0x87 * with R_64 = 0x1B and R_128 = 0x87
@ -245,7 +245,7 @@ static void cmac_pad( unsigned char padded_block[16],
( o )[i] = ( i1 )[i] ^ ( i2 )[i]; ( o )[i] = ( i1 )[i] ^ ( i2 )[i];
/* /*
* Update the CMAC state using an input block x * Update the CMAC state using an input block
*/ */
#define UPDATE_CMAC( x ) \ #define UPDATE_CMAC( x ) \
do { \ do { \
@ -283,11 +283,7 @@ int mbedtls_cmac_generate( mbedtls_cmac_context *ctx,
goto exit; goto exit;
} }
/* if( tag_len < 2 || tag_len > block_size || tag_len % 2 != 0 )
* Check in_len requirements: SP800-38B A
* 4 is a worst case bottom limit
*/
if( tag_len < 4 || tag_len > block_size || tag_len % 2 != 0 )
{ {
ret = MBEDTLS_ERR_CMAC_BAD_INPUT; ret = MBEDTLS_ERR_CMAC_BAD_INPUT;
goto exit; goto exit;