Merge commit '86cc97e55fe346502462284d2e636a2b3708163e' as 'Sources/OpenVPN3'

Sources/OpenVPN3/openvpn/mbedtls/crypto/ciphergcm.hpp

@@ -0,0 +1,170 @@
+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2017 OpenVPN Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    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 Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+// Wrap the mbed TLS GCM API.
+
+#ifndef OPENVPN_MBEDTLS_CRYPTO_CIPHERGCM_H
+#define OPENVPN_MBEDTLS_CRYPTO_CIPHERGCM_H
+
+#include <string>
+
+#include <mbedtls/gcm.h>
+
+#include <openvpn/common/size.hpp>
+#include <openvpn/common/exception.hpp>
+#include <openvpn/common/likely.hpp>
+#include <openvpn/crypto/static_key.hpp>
+#include <openvpn/crypto/cryptoalgs.hpp>
+
+namespace openvpn {
+  namespace MbedTLSCrypto {
+    class CipherContextGCM
+    {
+      CipherContextGCM(const CipherContextGCM&) = delete;
+      CipherContextGCM& operator=(const CipherContextGCM&) = delete;
+
+    public:
+      OPENVPN_EXCEPTION(mbedtls_gcm_error);
+
+      // mode parameter for constructor
+      enum {
+	MODE_UNDEF = MBEDTLS_OPERATION_NONE,
+	ENCRYPT = MBEDTLS_ENCRYPT,
+	DECRYPT = MBEDTLS_DECRYPT
+      };
+
+      // mbed TLS cipher constants
+      enum {
+	IV_LEN = 12,
+	AUTH_TAG_LEN = 16,
+	SUPPORTS_IN_PLACE_ENCRYPT = 1,
+      };
+
+#if 0
+      // mbed TLS encrypt/decrypt return values
+      enum {
+	GCM_AUTH_FAILED = MBEDTLS_ERR_GCM_AUTH_FAILED,
+	SUCCESS = 0,
+      };
+#endif
+
+      CipherContextGCM()
+	: initialized(false)
+      {
+      }
+
+      ~CipherContextGCM() { erase() ; }
+
+      void init(const CryptoAlgs::Type alg,
+		const unsigned char *key,
+		const unsigned int keysize,
+		const int mode) // unused
+      {
+	erase();
+
+	// get cipher type
+	unsigned int ckeysz = 0;
+	const mbedtls_cipher_id_t cid = cipher_type(alg, ckeysz);
+	if (ckeysz > keysize)
+	  throw mbedtls_gcm_error("insufficient key material");
+
+	// initialize cipher context
+	mbedtls_gcm_init(&ctx);
+	if (mbedtls_gcm_setkey(&ctx, cid, key, ckeysz * 8) < 0)
+	    throw mbedtls_gcm_error("mbedtls_gcm_setkey");
+
+	initialized = true;
+      }
+
+      void encrypt(const unsigned char *input,
+		   unsigned char *output,
+		   size_t length,
+		   const unsigned char *iv,
+		   unsigned char *tag,
+		   const unsigned char *ad,
+		   size_t ad_len)
+      {
+	check_initialized();
+	const int status = mbedtls_gcm_crypt_and_tag(&ctx, MBEDTLS_GCM_ENCRYPT,
+						     length, iv, IV_LEN, ad, ad_len,
+						     input, output, AUTH_TAG_LEN, tag);
+	if (unlikely(status))
+	  OPENVPN_THROW(mbedtls_gcm_error, "mbedtls_gcm_crypt_and_tag failed with status=" << status);
+      }
+
+      // input and output may NOT be equal
+      bool decrypt(const unsigned char *input,
+		  unsigned char *output,
+		  size_t length,
+		  const unsigned char *iv,
+		  const unsigned char *tag,
+		  const unsigned char *ad,
+		  size_t ad_len)
+      {
+	check_initialized();
+	const int status = mbedtls_gcm_auth_decrypt(&ctx, length, iv, IV_LEN, ad, ad_len, tag,
+						    AUTH_TAG_LEN, input, output);
+	return status == 0;
+      }
+
+      bool is_initialized() const { return initialized; }
+
+    private:
+      static mbedtls_cipher_id_t cipher_type(const CryptoAlgs::Type alg, unsigned int& keysize)
+      {
+	switch (alg)
+	  {
+	  case CryptoAlgs::AES_128_GCM:
+	    keysize = 16;
+	    return MBEDTLS_CIPHER_ID_AES;
+	  case CryptoAlgs::AES_192_GCM:
+	    keysize = 24;
+	    return MBEDTLS_CIPHER_ID_AES;
+	  case CryptoAlgs::AES_256_GCM:
+	    keysize = 32;
+	    return MBEDTLS_CIPHER_ID_AES;
+	  default:
+	    OPENVPN_THROW(mbedtls_gcm_error, CryptoAlgs::name(alg) << ": not usable");
+	  }
+      }
+
+      void erase()
+      {
+	if (initialized)
+	  {
+	    mbedtls_gcm_free(&ctx);
+	    initialized = false;
+	  }
+      }
+
+      void check_initialized() const
+      {
+	if (unlikely(!initialized))
+	  throw mbedtls_gcm_error("uninitialized");
+      }
+
+      bool initialized;
+      mbedtls_gcm_context ctx;
+    };
+  }
+}
+
+#endif