GCM in the cipher layer, step 1
- no support for additional data
- no support for tag
diff --git a/library/cipher.c b/library/cipher.c
index 60e1d91..733f6e5 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -34,6 +34,10 @@
#include "polarssl/cipher.h"
#include "polarssl/cipher_wrap.h"
+#if defined(POLARSSL_GCM_C)
+#include "polarssl/gcm.h"
+#endif
+
#include <stdlib.h>
#if defined(POLARSSL_ARC4_C) || defined(POLARSSL_CIPHER_NULL_CIPHER)
@@ -285,7 +289,14 @@
if( !strcasecmp( "AES-256-CTR", cipher_name ) )
return cipher_info_from_type( POLARSSL_CIPHER_AES_256_CTR );
#endif /* defined(POLARSSL_CIPHER_MODE_CTR) */
+
+#if defined(POLARSSL_GCM_C)
+ if( !strcasecmp( "AES-128-GCM", cipher_name ) )
+ return cipher_info_from_type( POLARSSL_CIPHER_AES_128_GCM );
+ if( !strcasecmp( "AES-256-GCM", cipher_name ) )
+ return cipher_info_from_type( POLARSSL_CIPHER_AES_256_GCM );
#endif
+#endif /* POLARSSL_AES_C */
#if defined(POLARSSL_ARC4_C)
if( !strcasecmp( "ARC4-128", cipher_name ) )
@@ -392,6 +403,16 @@
ctx->unprocessed_len = 0;
+#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 );
+ }
+#endif
+
memcpy( ctx->iv, iv, cipher_get_iv_size( ctx ) );
return 0;
@@ -416,7 +437,8 @@
return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
}
- if( ctx->cipher_info->mode == POLARSSL_MODE_CBC )
+ if( ctx->cipher_info->mode == POLARSSL_MODE_CBC ||
+ ctx->cipher_info->mode == POLARSSL_MODE_GCM )
{
/*
* If there is not enough data for a full block, cache it.
@@ -443,6 +465,18 @@
memcpy( &( ctx->unprocessed_data[ctx->unprocessed_len] ), input,
copy_len );
+#if defined(POLARSSL_GCM_C)
+ if( ctx->cipher_info->mode == POLARSSL_MODE_GCM )
+ {
+ if( 0 != ( ret = gcm_update( ctx->cipher_ctx,
+ cipher_get_block_size( ctx ),
+ ctx->unprocessed_data, output ) ) )
+ {
+ return ret;
+ }
+ }
+ else
+#endif
if( 0 != ( ret = ctx->cipher_info->base->cbc_func( ctx->cipher_ctx,
ctx->operation, cipher_get_block_size( ctx ), ctx->iv,
ctx->unprocessed_data, output ) ) )
@@ -479,11 +513,23 @@
*/
if( ilen )
{
+#if defined(POLARSSL_GCM_C)
+ if( ctx->cipher_info->mode == POLARSSL_MODE_GCM )
+ {
+ if( 0 != ( ret = gcm_update( ctx->cipher_ctx,
+ ilen, input, output ) ) )
+ {
+ return ret;
+ }
+ }
+ else
+#endif
if( 0 != ( ret = ctx->cipher_info->base->cbc_func( ctx->cipher_ctx,
ctx->operation, ilen, ctx->iv, input, output ) ) )
{
return ret;
}
+
*olen += ilen;
}
@@ -712,6 +758,28 @@
return 0;
}
+#if defined(POLARSSL_GCM_C)
+ if( POLARSSL_MODE_GCM == ctx->cipher_info->mode )
+ {
+ size_t tag_len = 0; // TODO
+ unsigned char tag[16];
+
+ if( 0 != ( ret = gcm_update( ctx->cipher_ctx,
+ ctx->unprocessed_len, ctx->unprocessed_data,
+ output ) ) )
+ {
+ return( ret );
+ }
+
+ *olen += ctx->unprocessed_len;
+
+ if( 0 != ( ret = gcm_finish( ctx->cipher_ctx, tag, tag_len ) ) )
+ return( ret );
+
+ return( 0 );
+ }
+#endif
+
if( POLARSSL_MODE_CBC == ctx->cipher_info->mode )
{
if( POLARSSL_ENCRYPT == ctx->operation )
diff --git a/library/cipher_wrap.c b/library/cipher_wrap.c
index 562f8b3..c8eee54 100644
--- a/library/cipher_wrap.c
+++ b/library/cipher_wrap.c
@@ -53,6 +53,10 @@
#include "polarssl/blowfish.h"
#endif
+#if defined(POLARSSL_GCM_C)
+#include "polarssl/gcm.h"
+#endif
+
#if defined(POLARSSL_MEMORY_C)
#include "polarssl/memory.h"
#else
@@ -235,6 +239,33 @@
#endif /* POLARSSL_CIPHER_MODE_CTR */
#if defined(POLARSSL_GCM_C)
+static void *gcm_ctx_alloc( void )
+{
+ return polarssl_malloc( sizeof( gcm_context ) );
+}
+
+static void gcm_ctx_free( void *ctx )
+{
+ polarssl_free( ctx );
+}
+
+static int gcm_setkey_wrap( void *ctx, const unsigned char *key, unsigned int key_length )
+{
+ return gcm_init( (gcm_context *) ctx, key, key_length );
+}
+
+const cipher_base_t gcm_aes_info = {
+ POLARSSL_CIPHER_ID_AES,
+ NULL,
+ NULL,
+ NULL,
+ NULL,
+ gcm_setkey_wrap,
+ gcm_setkey_wrap,
+ gcm_ctx_alloc,
+ gcm_ctx_free,
+};
+
const cipher_info_t aes_128_gcm_info = {
POLARSSL_CIPHER_AES_128_GCM,
POLARSSL_MODE_GCM,
@@ -242,7 +273,7 @@
"AES-128-GCM",
16,
16,
- &aes_info
+ &gcm_aes_info
};
const cipher_info_t aes_256_gcm_info = {
@@ -252,7 +283,7 @@
"AES-256-GCM",
16,
16,
- &aes_info
+ &gcm_aes_info
};
#endif /* POLARSSL_GCM_C */
diff --git a/library/gcm.c b/library/gcm.c
index 3e9969d..9c079bd 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -293,11 +293,11 @@
uint64_t orig_len = ctx->len * 8;
uint64_t orig_add_len = ctx->add_len * 8;
- memcpy( tag, ctx->base_ectr, tag_len );
-
if( tag_len > 16 )
return( POLARSSL_ERR_GCM_BAD_INPUT );
+ memcpy( tag, ctx->base_ectr, tag_len );
+
if( orig_len || orig_add_len )
{
memset( work_buf, 0x00, 16 );
