mirror of
https://github.com/Mbed-TLS/mbedtls.git
synced 2025-07-29 11:41:15 +03:00
Add ccm_encrypt_and_tag()
This commit is contained in:
Manuel Pégourié-Gonnard
286
library/ccm.c
286
library/ccm.c
@ -81,6 +81,206 @@ void ccm_free( ccm_context *ctx )
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memset( ctx, 0, sizeof( ccm_context ) );
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}
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#define UPDATE_CBC_MAC( src ) \
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{ \
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size_t olen; \
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\
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for( i = 0; i < 16; i++ ) \
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src[i] ^= y[i]; \
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\
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if( ( ret = cipher_update( &ctx->cipher_ctx, src, 16, \
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y, &olen ) ) != 0 ) \
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{ \
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return( ret ); \
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} \
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}
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#define CTR_CRYPT_BLOCK( dst, src ) \
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{ \
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size_t olen; \
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\
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if( ( ret = cipher_update( &ctx->cipher_ctx, ctr, 16, \
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dst, &olen ) ) != 0 ) \
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{ \
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return( ret ); \
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} \
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\
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for( i = 0; i < 16; i++ ) \
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dst[i] ^= src[i]; \
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}
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/*
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* Authenticated encryption
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*/
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int ccm_crypt_and_tag( ccm_context *ctx, size_t length,
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const unsigned char *iv, size_t iv_len,
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const unsigned char *add, size_t add_len,
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const unsigned char *input, unsigned char *output,
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unsigned char *tag, size_t tag_len )
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{
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int ret;
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unsigned char i;
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unsigned char q = 16 - 1 - iv_len;
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size_t len_left;
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unsigned char b[16];
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unsigned char y[16];
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unsigned char ctr[16];
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const unsigned char *src;
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unsigned char *dst;
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/*
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* Check length requirements: SP800-38C A.1
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* Additional requirement: a < 2^16 - 2^8 to simplify the code.
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* 'length' checked later (when writing it to the first block)
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*/
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if( tag_len < 4 || tag_len > 16 || tag_len % 2 != 0 )
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return( POLARSSL_ERR_CCM_BAD_INPUT );
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/* Also implies q is within bounds */
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if( iv_len < 7 || iv_len > 13 )
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return( POLARSSL_ERR_CCM_BAD_INPUT );
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if( add_len > 0xFF00 )
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return( POLARSSL_ERR_CCM_BAD_INPUT );
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/*
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* First block B_0:
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* 0 .. 0 flags
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* 1 .. iv_len nonce (aka iv)
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* iv_len+1 .. 15 length
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*
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* With flags as (bits):
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* 7 0
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* 6 add present?
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* 5 .. 3 (t - 2) / 2
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* 2 .. 0 q - 1
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*/
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b[0] = 0;
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b[0] |= ( add_len > 0 ) << 6;
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b[0] |= ( ( tag_len - 2 ) / 2 ) << 3;
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b[0] |= q - 1;
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memcpy( b + 1, iv, iv_len );
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for( i = 0, len_left = length; i < q; i++, len_left >>= 8 )
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b[15-i] = (unsigned char)( len_left & 0xFF );
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if( len_left > 0 )
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return( POLARSSL_ERR_CCM_BAD_INPUT );
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/* Start CBC-MAC with first block */
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memset( y, 0, 16 );
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UPDATE_CBC_MAC( b );
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/*
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* If there is additional data, update CBC-MAC with
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* add_len, add, 0 (padding to a block boundary)
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*/
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if( add_len > 0 )
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{
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size_t use_len;
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len_left = add_len;
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src = add;
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memset( b, 0, 16 );
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b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF );
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b[1] = (unsigned char)( ( add_len ) & 0xFF );
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use_len = len_left < 16 - 2 ? len_left : 16 - 2;
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memcpy( b + 2, src, use_len );
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len_left -= use_len;
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src += use_len;
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UPDATE_CBC_MAC( b );
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while( len_left > 16 )
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{
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memcpy( b, src, 16 );
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UPDATE_CBC_MAC( b );
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len_left -= 16;
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src += 16;
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}
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if( len_left > 0 )
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{
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memset( b, 0, 16 );
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memcpy( b, src, len_left );
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UPDATE_CBC_MAC( b );
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}
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}
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/*
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* Counter block:
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* 0 .. 0 flags
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* 1 .. iv_len nonce (aka iv)
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* iv_len+1 .. 15 counter (initially 1)
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*
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* With flags as (bits):
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* 7 .. 3 0
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* 2 .. 0 q - 1
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*/
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ctr[0] = q - 1;
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memcpy( ctr + 1, iv, iv_len );
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memset( ctr + 1 + iv_len, 0, q );
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ctr[15] = 1;
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len_left = length;
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src = input;
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dst = output;
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/*
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* Authenticate and encrypt message
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*/
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while( len_left > 16 )
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{
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memcpy( b, src, 16 );
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UPDATE_CBC_MAC( b );
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CTR_CRYPT_BLOCK( dst, src );
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dst += 16;
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src += 16;
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len_left -= 16;
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for( i = 0; i < q; i++ )
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if( ++ctr[15-i] != 0 )
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break;
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}
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if( len_left > 0 )
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{
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unsigned char mask[16];
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size_t olen;
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memset( b, 0, 16 );
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memcpy( b, src, len_left );
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UPDATE_CBC_MAC( b );
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if( ( ret = cipher_update( &ctx->cipher_ctx, ctr, 16,
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mask, &olen ) ) != 0 )
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{
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return( ret );
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}
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for( i = 0; i < len_left; i++ )
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dst[i] = src[i] ^ mask[i];
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}
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/*
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* Authentication: reset counter and encrypt internal tag
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*/
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for( i = 0; i < q; i++ )
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ctr[15-i] = 0;
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CTR_CRYPT_BLOCK( b, y );
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memcpy( tag, b, tag_len );
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return( 0 );
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}
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#if defined(POLARSSL_SELF_TEST) && defined(POLARSSL_AES_C)
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@ -90,10 +290,92 @@ void ccm_free( ccm_context *ctx )
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#define polarssl_printf printf
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#endif
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/*
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* Examples 1 to 3 from SP800-38C Appendix C
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*/
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#define NB_TESTS 3
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/*
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* The data is the same for all tests, only the used length changes
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*/
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static const unsigned char key[] = {
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0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
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0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
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};
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static const unsigned char iv[] = {
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
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0x18, 0x19, 0x1a, 0x1b
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};
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static const unsigned char ad[] = {
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0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
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0x10, 0x11, 0x12, 0x13
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};
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static const unsigned char msg[] = {
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0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
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0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
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0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
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};
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static const size_t iv_len [NB_TESTS] = { 7, 8, 12 };
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static const size_t add_len[NB_TESTS] = { 8, 16, 20 };
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static const size_t msg_len[NB_TESTS] = { 4, 16, 24 };
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static const size_t tag_len[NB_TESTS] = { 4, 6, 8 };
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static const unsigned char res[NB_TESTS][32] = {
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{ 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d },
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{ 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62,
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0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d,
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0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd },
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{ 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a,
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0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b,
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0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5,
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0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 }
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};
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int ccm_self_test( int verbose )
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{
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if( verbose != 0 )
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polarssl_printf( " CCM: skip\n" );
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ccm_context ctx;
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unsigned char out[32];
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size_t i;
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int ret;
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if( ccm_init( &ctx, POLARSSL_CIPHER_ID_AES, key, 8 * sizeof key ) != 0 )
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{
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if( verbose != 0 )
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polarssl_printf( " CCM: setup failed" );
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return( 1 );
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}
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for( i = 0; i < NB_TESTS; i++ )
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{
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if( verbose != 0 )
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polarssl_printf( " CCM-AES #%u: ", (unsigned int) i + 1 );
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ret = ccm_crypt_and_tag( &ctx, msg_len[i],
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iv, iv_len[i], ad, add_len[i],
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msg, out,
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out + msg_len[i], tag_len[i] );
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if( ret != 0 ||
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memcmp( out, res[i], msg_len[i] + tag_len[i] ) != 0 )
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{
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if( verbose != 0 )
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polarssl_printf( "failed\n" );
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return( 1 );
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}
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if( verbose != 0 )
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polarssl_printf( "passed\n" );
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}
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ccm_free( &ctx );
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if( verbose != 0 )
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polarssl_printf( "\n" );
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