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- Added input checking and more efficient buffer overlap use

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This commit is contained in:
Paul Bakker 2012-04-18 14:17:01 +00:00
parent 369e14bbf1
commit fc5183cf5d
1 changed files with 14 additions and 14 deletions
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28
library/gcm.c
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@ -188,7 +188,6 @@ int gcm_crypt_and_tag( gcm_context *ctx,
unsigned char buf[16];
unsigned char work_buf[16];
size_t i;
unsigned char cb;
const unsigned char *p;
unsigned char *out_p = output;
size_t use_len;
@ -201,6 +200,12 @@ int gcm_crypt_and_tag( gcm_context *ctx,
memset( tag, 0x00, tag_len );
memset( buf, 0x00, 16 );
if( ( mode == GCM_DECRYPT && output <= input && ( input - output ) < 8 ) ||
( output > input && (size_t) ( output - input ) < length ) )
{
return( POLARSSL_ERR_GCM_BAD_INPUT );
}
if( mode == GCM_ENCRYPT )
xor_p = (unsigned char **) &out_p;
else
@ -270,11 +275,9 @@ int gcm_crypt_and_tag( gcm_context *ctx,
{
use_len = ( length < 16 ) ? length : 16;
i = 15;
do {
y[i]++;
cb = y[i] == 0;
} while( i-- && cb );
for( i = 16; i > 0; i-- )
if( ++y[i - 1] != 0 )
break;
aes_crypt_ecb( &ctx->aes_ctx, AES_ENCRYPT, y, ectr );
@ -282,21 +285,18 @@ int gcm_crypt_and_tag( gcm_context *ctx,
{
((uint64_t *) out_p)[0] = ((uint64_t *) ectr)[0] ^
((uint64_t *) p)[0];
((uint64_t *) buf)[0] ^= ((uint64_t *) (*xor_p))[0];
((uint64_t *) out_p)[1] = ((uint64_t *) ectr)[1] ^
((uint64_t *) p)[1];
}
else
for( i = 0; i < use_len; i++ )
out_p[i] = ectr[i] ^ p[i];
if( use_len == 16 )
{
((uint64_t *) buf)[0] ^= ((uint64_t *) (*xor_p))[0];
((uint64_t *) buf)[1] ^= ((uint64_t *) (*xor_p))[1];
}
else
for( i = 0; i < use_len; i++ )
{
out_p[i] = ectr[i] ^ p[i];
buf[i] ^= (*xor_p)[i];
}
gcm_mult( ctx, buf, buf );