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Change cipher prototypes for GCM

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This commit is contained in:
Manuel Pégourié-Gonnard
2013-08-31 17:31:03 +02:00
parent 20d6a17af9
commit 9241be7ac5
9 changed files with 94 additions and 39 deletions
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41
library/cipher.c
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@ -396,7 +396,9 @@ int cipher_setkey( cipher_context_t *ctx, const unsigned char *key,
return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
}
int cipher_reset( cipher_context_t *ctx, const unsigned char *iv )
int cipher_reset( cipher_context_t *ctx,
const unsigned char *iv, size_t iv_len,
const unsigned char *ad, size_t ad_len )
{
if( NULL == ctx || NULL == ctx->cipher_info || NULL == iv )
return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
@ -406,11 +408,13 @@ int cipher_reset( cipher_context_t *ctx, const unsigned char *iv )
#if defined(POLARSSL_GCM_C)
if( POLARSSL_MODE_GCM == ctx->cipher_info->mode )
{
// TODO: allow other IV length
// TODO: allow additional data
return gcm_starts( ctx->cipher_ctx, ctx->operation,
iv, 12, (unsigned char *) "", 0 );
iv, iv_len, ad, ad_len );
}
#else
((void) ad);
((void) ad_len);
((void) iv_len);
#endif
memcpy( ctx->iv, iv, cipher_get_iv_size( ctx ) );
@ -742,7 +746,9 @@ static int get_no_padding( unsigned char *input, size_t input_len,
return 0;
}
int cipher_finish( cipher_context_t *ctx, unsigned char *output, size_t *olen)
int cipher_finish( cipher_context_t *ctx,
unsigned char *output, size_t *olen,
unsigned char *tag, size_t tag_len )
{
int ret = 0;
@ -761,8 +767,9 @@ int cipher_finish( cipher_context_t *ctx, unsigned char *output, size_t *olen)
#if defined(POLARSSL_GCM_C)
if( POLARSSL_MODE_GCM == ctx->cipher_info->mode )
{
size_t tag_len = 0; // TODO
unsigned char tag[16];
unsigned char check_tag[16];
size_t i;
int diff;
if( 0 != ( ret = gcm_update( ctx->cipher_ctx,
ctx->unprocessed_len, ctx->unprocessed_data,
@ -773,11 +780,29 @@ int cipher_finish( cipher_context_t *ctx, unsigned char *output, size_t *olen)
*olen += ctx->unprocessed_len;
if( 0 != ( ret = gcm_finish( ctx->cipher_ctx, tag, tag_len ) ) )
if( 0 != ( ret = gcm_finish( ctx->cipher_ctx, check_tag, tag_len ) ) )
return( ret );
/* On encryption, write the tag */
if( POLARSSL_ENCRYPT == ctx->operation )
{
if( tag_len != 0 )
memcpy( tag, check_tag, tag_len );
return( 0 );
}
/* On decryption, check the tag (in "constant-time") */
for( diff = 0, i = 0; i < tag_len; i++ )
diff |= tag[i] ^ check_tag[i];
if( diff != 0 )
return( POLARSSL_ERR_GCM_AUTH_FAILED );
return( 0 );
}
#else
((void) tag);
((void) tag_len);
#endif
if( POLARSSL_MODE_CBC == ctx->cipher_info->mode )