- Added base Galois/Counter mode (GCM) for AES

include/polarssl/config.h

@@ -447,6 +447,17 @@
  */
 #define POLARSSL_ERROR_C
 
+/**
+ * \def POLARSSL_GCM_C
+ *
+ * Enable the Galois/Counter Mode (GCM) for AES
+ *
+ * Module:  library/gcm.c
+ *
+ * Requires: POLARSSL_AES_C
+ */
+#define POLARSSL_GCM_C
+
 /**
  * \def POLARSSL_HAVEGE_C
  *

include/polarssl/error.h

@@ -49,6 +49,7 @@
  *
  * Module   Nr  Codes assigned 
  * MPI       7  0x0002-0x0010
+ * GCM       1  0x0012-0x0012
  * AES       2  0x0020-0x0022
  * CAMELLIA  2  0x0024-0x0026
  * XTEA      1  0x0028-0x0028

include/polarssl/gcm.h

@@ -0,0 +1,132 @@
+/**
+ * \file gcm.h
+ *
+ * \brief Galois/Counter mode for AES
+ *
+ *  Copyright (C) 2006-2012, Brainspark B.V.
+ *
+ *  This file is part of PolarSSL (http://www.polarssl.org)
+ *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
+ *
+ *  All rights reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifndef POLARSSL_GCM_H
+#define POLARSSL_GCM_H
+
+#include "aes.h"
+
+#include <stdint.h>
+
+#define GCM_ENCRYPT     1
+#define GCM_DECRYPT     0
+
+#define POLARSSL_ERR_GCM_AUTH_FAILED                       -0x0012  /**< Authenticated decryption failed. */
+
+/**
+ * \brief          GCM context structure
+ */
+typedef struct {
+    aes_context aes_ctx;        /*!< AES context used */
+    uint64_t HL[16];            /*!< Precalculated HTable */
+    uint64_t HH[16];            /*!< Precalculated HTable */
+}
+gcm_context;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief           GCM initialization (encryption)
+ *
+ * \param ctx       GCM context to be initialized
+ * \param key       encryption key
+ * \param keysize   must be 128, 192 or 256
+ *
+ * \return          0 if successful, or POLARSSL_ERR_AES_INVALID_KEY_LENGTH
+ */
+int gcm_init( gcm_context *ctx, const unsigned char *key, unsigned int keysize );
+
+/**
+ * \brief           GCM buffer encryption/decryption using AES
+ *
+ * \param ctx       GCM context
+ * \param mode      GCM_ENCRYPT or GCM_DECRYPT
+ * \param length    length of the input data
+ * \param iv        initialization vector
+ * \param iv_len    length of IV
+ * \param add       additional data
+ * \param add_len   length of additional data
+ * \param input     buffer holding the input data
+ * \param output    buffer for holding the output data
+ * \param tag_len   length of the tag to generate
+ * \param tag       buffer for holding the tag
+ *
+ * \return         0 if successful
+ */
+int gcm_crypt_and_tag( gcm_context *ctx,
+                       int mode,
+                       size_t length,
+                       const unsigned char *iv,
+                       size_t iv_len,
+                       const unsigned char *add,
+                       size_t add_len,
+                       const unsigned char *input,
+                       unsigned char *output,
+                       size_t tag_len,
+                       unsigned char *tag );
+
+/**
+ * \brief           GCM buffer authenticated decryption using AES
+ *
+ * \param ctx       GCM context
+ * \param length    length of the input data
+ * \param iv        initialization vector
+ * \param iv_len    length of IV
+ * \param add       additional data
+ * \param add_len   length of additional data
+ * \param tag       buffer holding the tag
+ * \param tag_len   length of the tag 
+ * \param input     buffer holding the input data
+ * \param output    buffer for holding the output data
+ *
+ * \return         0 if successful and authenticated,
+ *                 POLARSSL_ERR_GCM_AUTH_FAILED if tag does not match
+ */
+int gcm_auth_decrypt( gcm_context *ctx,
+                      size_t length,
+                      const unsigned char *iv,
+                      size_t iv_len,
+                      const unsigned char *add,
+                      size_t add_len,
+                      const unsigned char *tag, 
+                      size_t tag_len,
+                      const unsigned char *input,
+                      unsigned char *output );
+
+/**
+ * \brief          Checkup routine
+ *
+ * \return         0 if successful, or 1 if the test failed
+ */
+int gcm_self_test( int verbose );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* gcm.h */