CCM source cosmetics/tune-ups
- source a bit shorter - generated code slightly smaller - preserving performance
This commit is contained in:
parent
58d78a8d70
commit
aed6065793
1 changed files with 58 additions and 87 deletions
145
library/ccm.c
145
library/ccm.c
|
@ -84,33 +84,33 @@ void ccm_free( ccm_context *ctx )
|
|||
memset( ctx, 0, sizeof( ccm_context ) );
|
||||
}
|
||||
|
||||
#define UPDATE_CBC_MAC( src ) \
|
||||
{ \
|
||||
size_t olen; \
|
||||
\
|
||||
for( i = 0; i < 16; i++ ) \
|
||||
src[i] ^= y[i]; \
|
||||
\
|
||||
if( ( ret = cipher_update( &ctx->cipher_ctx, src, 16, \
|
||||
y, &olen ) ) != 0 ) \
|
||||
{ \
|
||||
return( ret ); \
|
||||
} \
|
||||
}
|
||||
/*
|
||||
* Macros for common operations.
|
||||
* Results in smaller compiled code than static inline functions.
|
||||
*/
|
||||
|
||||
#define CTR_CRYPT_BLOCK( dst, src ) \
|
||||
{ \
|
||||
size_t olen; \
|
||||
\
|
||||
if( ( ret = cipher_update( &ctx->cipher_ctx, ctr, 16, \
|
||||
dst, &olen ) ) != 0 ) \
|
||||
{ \
|
||||
return( ret ); \
|
||||
} \
|
||||
\
|
||||
for( i = 0; i < 16; i++ ) \
|
||||
dst[i] ^= src[i]; \
|
||||
}
|
||||
/*
|
||||
* 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.)
|
||||
*/
|
||||
#define UPDATE_CBC_MAC \
|
||||
for( i = 0; i < 16; i++ ) \
|
||||
y[i] ^= b[i]; \
|
||||
\
|
||||
if( ( ret = cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \
|
||||
return( ret );
|
||||
|
||||
/*
|
||||
* Encrypt or decrypt a partial block with CTR
|
||||
* Warning: using b for temporary storage! src and dst must not be b!
|
||||
* (This avoids allocating one more 16 bytes buffer.)
|
||||
*/
|
||||
#define CTR_CRYPT( dst, src, len ) \
|
||||
if( ( ret = cipher_update( &ctx->cipher_ctx, ctr, 16, b, &olen ) ) != 0 ) \
|
||||
return( ret ); \
|
||||
\
|
||||
for( i = 0; i < len; i++ ) \
|
||||
dst[i] = src[i] ^ b[i];
|
||||
|
||||
/*
|
||||
* Authenticated encryption or decryption
|
||||
|
@ -124,7 +124,7 @@ static int ccm_auth_crypt( ccm_context *ctx, int mode, size_t length,
|
|||
int ret;
|
||||
unsigned char i;
|
||||
unsigned char q = 16 - 1 - iv_len;
|
||||
size_t len_left;
|
||||
size_t len_left, olen;
|
||||
unsigned char b[16];
|
||||
unsigned char y[16];
|
||||
unsigned char ctr[16];
|
||||
|
@ -174,7 +174,7 @@ static int ccm_auth_crypt( ccm_context *ctx, int mode, size_t length,
|
|||
|
||||
/* Start CBC-MAC with first block */
|
||||
memset( y, 0, 16 );
|
||||
UPDATE_CBC_MAC( b );
|
||||
UPDATE_CBC_MAC;
|
||||
|
||||
/*
|
||||
* If there is additional data, update CBC-MAC with
|
||||
|
@ -195,28 +195,23 @@ static int ccm_auth_crypt( ccm_context *ctx, int mode, size_t length,
|
|||
len_left -= use_len;
|
||||
src += use_len;
|
||||
|
||||
UPDATE_CBC_MAC( b );
|
||||
UPDATE_CBC_MAC;
|
||||
|
||||
while( len_left > 16 )
|
||||
while( len_left > 0 )
|
||||
{
|
||||
memcpy( b, src, 16 );
|
||||
UPDATE_CBC_MAC( b );
|
||||
use_len = len_left > 16 ? 16 : len_left;
|
||||
|
||||
len_left -= 16;
|
||||
src += 16;
|
||||
}
|
||||
|
||||
if( len_left > 0 )
|
||||
{
|
||||
memset( b, 0, 16 );
|
||||
memcpy( b, src, len_left );
|
||||
memcpy( b, src, use_len );
|
||||
UPDATE_CBC_MAC;
|
||||
|
||||
UPDATE_CBC_MAC( b );
|
||||
len_left -= use_len;
|
||||
src += use_len;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Counter block:
|
||||
* Prepare counter block for encryption:
|
||||
* 0 .. 0 flags
|
||||
* 1 .. iv_len nonce (aka iv)
|
||||
* iv_len+1 .. 15 counter (initially 1)
|
||||
|
@ -230,34 +225,39 @@ static int ccm_auth_crypt( ccm_context *ctx, int mode, size_t length,
|
|||
memset( ctr + 1 + iv_len, 0, q );
|
||||
ctr[15] = 1;
|
||||
|
||||
/*
|
||||
* Authenticate and {en,de}crypt the message.
|
||||
*
|
||||
* The only difference between encryption and decryption is
|
||||
* the respective order of authentication and {en,de}cryption.
|
||||
*/
|
||||
len_left = length;
|
||||
src = input;
|
||||
dst = output;
|
||||
|
||||
/*
|
||||
* Authenticate and crypt message
|
||||
* The only difference between encryption and decryption is
|
||||
* the respective order of authentication and {en,de}cryption
|
||||
*/
|
||||
while( len_left > 16 )
|
||||
while( len_left > 0 )
|
||||
{
|
||||
unsigned char use_len = len_left > 16 ? 16 : len_left;
|
||||
|
||||
if( mode == CCM_ENCRYPT )
|
||||
{
|
||||
memcpy( b, src, 16 );
|
||||
UPDATE_CBC_MAC( b );
|
||||
memset( b, 0, 16 );
|
||||
memcpy( b, src, use_len );
|
||||
UPDATE_CBC_MAC;
|
||||
}
|
||||
|
||||
CTR_CRYPT_BLOCK( dst, src );
|
||||
CTR_CRYPT( dst, src, use_len );
|
||||
|
||||
if( mode == CCM_DECRYPT )
|
||||
{
|
||||
memcpy( b, dst, 16 );
|
||||
UPDATE_CBC_MAC( b );
|
||||
memset( b, 0, 16 );
|
||||
memcpy( b, dst, use_len );
|
||||
UPDATE_CBC_MAC;
|
||||
}
|
||||
|
||||
dst += 16;
|
||||
src += 16;
|
||||
len_left -= 16;
|
||||
dst += use_len;
|
||||
src += use_len;
|
||||
len_left -= use_len;
|
||||
|
||||
/*
|
||||
* Increment counter.
|
||||
|
@ -268,43 +268,14 @@ static int ccm_auth_crypt( ccm_context *ctx, int mode, size_t length,
|
|||
break;
|
||||
}
|
||||
|
||||
if( len_left > 0 )
|
||||
{
|
||||
unsigned char mask[16];
|
||||
size_t olen;
|
||||
|
||||
if( mode == CCM_ENCRYPT )
|
||||
{
|
||||
memset( b, 0, 16 );
|
||||
memcpy( b, src, len_left );
|
||||
UPDATE_CBC_MAC( b );
|
||||
}
|
||||
|
||||
if( ( ret = cipher_update( &ctx->cipher_ctx, ctr, 16,
|
||||
mask, &olen ) ) != 0 )
|
||||
{
|
||||
return( ret );
|
||||
}
|
||||
|
||||
for( i = 0; i < len_left; i++ )
|
||||
dst[i] = src[i] ^ mask[i];
|
||||
|
||||
if( mode == CCM_DECRYPT )
|
||||
{
|
||||
memset( b, 0, 16 );
|
||||
memcpy( b, dst, len_left );
|
||||
UPDATE_CBC_MAC( b );
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Authentication: reset counter and {en,de}crypt internal tag
|
||||
* Authentication: reset counter and crypt/mask internal tag
|
||||
*/
|
||||
for( i = 0; i < q; i++ )
|
||||
ctr[15-i] = 0;
|
||||
|
||||
CTR_CRYPT_BLOCK( b, y );
|
||||
memcpy( tag, b, tag_len );
|
||||
CTR_CRYPT( y, y, 16 );
|
||||
memcpy( tag, y, tag_len );
|
||||
|
||||
return( 0 );
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue