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cmac: more cosmetic changes
This commit is contained in:
Manuel Pégourié-Gonnard
Simon Butcher
parent
ab9c5fd9b3
commit
7b555f2928
@ -108,6 +108,7 @@ int mbedtls_cmac_verify( mbedtls_cmac_context *ctx,
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/**
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* \brief AES-CMAC-128-PRF
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* TODO: add reference to the standard
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*
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* \param ctx CMAC context
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* \param key PRF key
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@ -115,6 +116,7 @@ int mbedtls_cmac_verify( mbedtls_cmac_context *ctx,
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* \param input buffer holding the input data
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* \param in_len length of the input data in bytes
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* \param tag buffer holding the tag to verify (16 bytes)
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* TODO: update description of tag
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*
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* \return 0 if successful
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*/
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@ -69,7 +69,8 @@ void mbedtls_cmac_init( mbedtls_cmac_context *ctx )
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*
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* Input and output MUST not point to the same buffer
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*/
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static void multiply_by_u( unsigned char *output, const unsigned char *input )
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static void cmac_multiply_by_u( unsigned char *output,
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const unsigned char *input )
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{
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const unsigned char Rb = 0x87; /* block size 16 only */
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unsigned char mask;
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@ -101,7 +102,7 @@ static void multiply_by_u( unsigned char *output, const unsigned char *input )
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/*
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* Generate subkeys
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*/
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static int generate_subkeys( mbedtls_cmac_context *ctx )
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static int cmac_generate_subkeys( mbedtls_cmac_context *ctx )
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{
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int ret;
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unsigned char L[16];
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@ -118,14 +119,17 @@ static int generate_subkeys( mbedtls_cmac_context *ctx )
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/*
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* Generate K1 and K2
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*/
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multiply_by_u( ctx->K1, L );
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multiply_by_u( ctx->K2, ctx->K1 );
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cmac_multiply_by_u( ctx->K1, L );
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cmac_multiply_by_u( ctx->K2, ctx->K1 );
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mbedtls_zeroize( L, sizeof( L ) );
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return( 0 );
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}
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/*
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* Set key and prepare context for use
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*/
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int mbedtls_cmac_setkey( mbedtls_cmac_context *ctx,
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mbedtls_cipher_id_t cipher,
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const unsigned char *key,
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@ -153,7 +157,7 @@ int mbedtls_cmac_setkey( mbedtls_cmac_context *ctx,
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return( ret );
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}
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return( generate_subkeys( ctx ) );
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return( cmac_generate_subkeys( ctx ) );
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}
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/*
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@ -171,7 +175,7 @@ void mbedtls_cmac_free( mbedtls_cmac_context *ctx )
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* We can't use the padding option from the cipher layer, as it only works for
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* CBC and we use ECB mode, and anyway we need to XOR K1 or K2 in addition.
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*/
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static void padding( unsigned char padded_block[16],
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static void cmac_pad( unsigned char padded_block[16],
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const unsigned char *last_block,
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size_t length )
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{
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@ -237,7 +241,7 @@ int mbedtls_cmac_generate( mbedtls_cmac_context *ctx,
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/* Calculate last block */
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if( needs_padding )
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{
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padding( M_last, input + 16 * ( n - 1 ), in_len % 16 );
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cmac_pad( M_last, input + 16 * ( n - 1 ), in_len % 16 );
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XOR_128( M_last, M_last, ctx->K2 );
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}
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else
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@ -262,7 +266,7 @@ int mbedtls_cmac_generate( mbedtls_cmac_context *ctx,
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#undef UPDATE_CMAC
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/*
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* Authenticated decryption
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* Verify tag on complete message
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*/
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int mbedtls_cmac_verify( mbedtls_cmac_context *ctx,
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const unsigned char *input, size_t in_len,
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@ -281,18 +285,19 @@ int mbedtls_cmac_verify( mbedtls_cmac_context *ctx,
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/* Check tag in "constant-time" */
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for( diff = 0, i = 0; i < tag_len; i++ )
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{
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diff |= tag[i] ^ check_tag[i];
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}
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if( diff != 0 )
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{
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return( MBEDTLS_ERR_CMAC_VERIFY_FAILED );
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}
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return( 0 );
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}
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/*
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* PRF based on CMAC with AES-128
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* TODO: add reference to the standard
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* TODO: do we need to take a cmac_context as an argument here?
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*/
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int mbedtls_aes_cmac_prf_128( mbedtls_cmac_context *ctx,
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const unsigned char *key, size_t key_length,
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const unsigned char *input, size_t in_len,
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@ -317,22 +322,17 @@ int mbedtls_aes_cmac_prf_128( mbedtls_cmac_context *ctx,
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ret = mbedtls_cmac_setkey( &zero_ctx, MBEDTLS_CIPHER_ID_AES,
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zero_key, 8 * sizeof zero_key );
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if( ret != 0 )
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{
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return( ret );
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}
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ret = mbedtls_cmac_generate( &zero_ctx, key, key_length, int_key, 16 );
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if( ret != 0 )
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{
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return( ret );
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}
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}
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ret = mbedtls_cmac_setkey( ctx, MBEDTLS_CIPHER_ID_AES,
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int_key, 8 * sizeof int_key );
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if( ret != 0 )
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{
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return( ret );
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}
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mbedtls_zeroize( int_key, sizeof( int_key ) );
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@ -341,7 +341,7 @@ int mbedtls_aes_cmac_prf_128( mbedtls_cmac_context *ctx,
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#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
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/*
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* Examples 1 to 4 from SP800-3B corrected Appendix D.1
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* Examples 1 to 4 from SP800-38B corrected Appendix D.1
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* http://csrc.nist.gov/publications/nistpubs/800-38B/Updated_CMAC_Examples.pdf
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*/
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@ -456,7 +456,7 @@ int mbedtls_cmac_self_test( int verbose )
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if( mbedtls_cmac_setkey( &ctx, MBEDTLS_CIPHER_ID_AES, key, 8 * sizeof key ) != 0 )
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{
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if( verbose != 0 )
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mbedtls_printf( " CMAC: setup failed" );
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mbedtls_printf( " CMAC: setup failed\n" );
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return( 1 );
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}
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@ -465,7 +465,7 @@ int mbedtls_cmac_self_test( int verbose )
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( memcmp( ctx.K2, K2, 16 ) != 0 ) )
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{
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if( verbose != 0 )
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mbedtls_printf( " CMAC: subkey generation failed" );
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mbedtls_printf( " CMAC: subkey generation failed\n" );
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return( 1 );
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}
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