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authorArne Schwabe <arne@rfc2549.org>2012-04-16 19:21:14 +0200
committerArne Schwabe <arne@rfc2549.org>2012-04-16 19:21:14 +0200
commit3e4d8f433239c40311037616b1b8833a06651ae0 (patch)
tree98ab7fce0d011d34677b0beb762d389cb5c39199 /openvpn/doc/doxygen/doc_data_crypto.h
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+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (see the file COPYING included with this
+ * distribution); if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+/**
+ * @file
+ * Data Channel Crypto module documentation file.
+ */
+
+/**
+ * @addtogroup data_crypto Data Channel Crypto module
+ *
+ * The Data Channel Crypto Module performs cryptographic operations on
+ * data channel packets.
+ *
+ * @par Security parameters
+ * This module is merely the user of a VPN tunnel's security parameters.
+ * It does not perform the negotiation and setup of the security
+ * parameters, nor the %key generation involved. These actions are done
+ * by the \link control_processor Control Channel Processor\endlink. This
+ * module receives the appropriate security parameters from that module in
+ * the form of a \c crypto_options structure when they are necessary for
+ * processing a packet.
+ *
+ * @par Packet processing functions
+ * This module receives data channel packets from the \link data_control
+ * Data Channel Control module\endlink and processes them according to the
+ * security parameters of the packet's VPN tunnel. The \link data_control
+ * Data Channel Control module\endlink uses the following interface
+ * functions:
+ * - For packets which will be sent to a remote OpenVPN peer:
+ * - \c tls_pre_encrypt()
+ * - \c openvpn_encrypt()
+ * - \c tls_post_encrypt()
+ * - For packets which have been received from a remote OpenVPN peer:
+ * - \c tls_pre_decrypt() (documented as part of the \link
+ * external_multiplexer External Multiplexer\endlink)
+ * - \c openvpn_decrypt()
+ *
+ * @par Settings that control this module's activity
+ * Whether or not the Data Channel Crypto module is active depends on the
+ * compile-time \c ENABLE_CRYPTO and \c ENABLE_SSL preprocessor macros. How it
+ * processes packets received from the \link data_control Data Channel
+ * Control module\endlink at runtime depends on the associated \c
+ * crypto_options structure. To perform cryptographic operations, the \c
+ * crypto_options.key_ctx_bi must contain the correct cipher and HMAC
+ * security parameters for the direction the packet is traveling in.
+ *
+ * @par Crypto algorithms
+ * This module uses the crypto algorithm implementations of the external
+ * OpenSSL library. More precisely, it uses the OpenSSL library's \c
+ * EVP_Cipher* and \c HMAC_* set of functions to perform cryptographic
+ * operations on data channel packets.
+ */