+++ /dev/null
-/* -*-c-*-
- *
- * $Id$
- *
- * Protocol definition for TrIPE
- *
- * (c) 2003 Straylight/Edgeware
- */
-
-/*----- Licensing notice --------------------------------------------------*
- *
- * This file is part of Trivial IP Encryption (TrIPE).
- *
- * TrIPE 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.
- *
- * TrIPE 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 TrIPE; if not, write to the Free Software Foundation,
- * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- */
-
-#ifndef TRIPE_PROTOCOL_H
-#define TRIPE_PROTOCOL_H
-
-/*----- TrIPE protocol ----------------------------------------------------*/
-
-/* --- TrIPE message format --- *
- *
- * A packet begins with a single-byte message type. The top four bits are a
- * category code used to send the message to the right general place in the
- * code; the bottom bits identify the actual message type.
- */
-
-#define MSG_CATMASK 0xf0
-#define MSG_TYPEMASK 0x0f
-
-/* --- Encrypted message packets --- *
- *
- * Messages of category @MSG_PACKET@ contain encrypted network packets. The
- * message content is a symmetric-encrypted block (see below). Reception of
- * a packet encrypted under a new key implicitly permits that key to be used
- * to send further packets.
- *
- * The only packet type accepted is zero.
- *
- * Packets may be encrypted under any live keyset, but should use the most
- * recent one.
- */
-
-#define MSG_PACKET 0x00
-
-/* --- Key exchange packets --- */
-
-#define MSG_KEYEXCH 0x10
-
-#define KX_PRECHAL 0u
-#define KX_CHAL 1u
-#define KX_REPLY 2u
-#define KX_SWITCH 3u
-#define KX_SWITCHOK 4u
-#define KX_NMSG 5u
-
-/* --- Miscellaneous packets --- */
-
-#define MSG_MISC 0x20
-
-#define MISC_NOP 0u /* Do nothing; ignore me */
-#define MISC_PING 1u /* Transport-level ping */
-#define MISC_PONG 2u /* Transport-level ping response */
-#define MISC_EPING 3u /* Encrypted ping */
-#define MISC_EPONG 4u /* Encrypted ping response */
-#define MISC_GREET 5u /* A greeting from a NATed peer */
-
-/* --- Symmetric encryption and keysets --- *
- *
- * Packets consist of an 80-bit MAC, a 32-bit sequence number, and the
- * encrypted payload.
- *
- * The plaintext is encrypted using Blowfish in CBC mode with ciphertext
- * stealing (as described in [Schneier]). The initialization vector is
- * selected randomly, and prepended to the actual ciphertext.
- *
- * The MAC is computed using the HMAC construction with RIPEMD160 over the
- * sequence number and the ciphertext (with IV); the first 80 bits of the
- * output are used. (This is the minimum allowed by the draft FIPS for HMAC,
- * and the recommended truncation.)
- *
- * A keyset consists of
- *
- * * an integrity (MAC) key;
- * * a confidentiality (encryption) key; and
- * * a sequence numbering space
- *
- * in each direction. The packets sent by a host encrypted under a
- * particular keyset are assigned consecutive sequence numbers starting from
- * zero. The receiving host must ensure that it only accepts each packet at
- * most once. It should maintain a window of sequence numbers: packets with
- * numbers beyond the end of the window are accepted and cause the window to
- * be advanced; packets with numbers before the start of the window are
- * rejected; packets with numbers which appear within the window are accepted
- * only if the number has not been seen before.
- *
- * When a host sends a @KX_SWITCH@ or @KX_SWITCHOK@ message, it installs the
- * newly-negotiated keyset in a `listen-only' state: it may not send a packet
- * encrypted under the keyset until either it has received a @KX_SWITCH@ or
- * @KX_SWITCHOK@ message, or a @MSG_PACKET@ encrypted under the keyset, from
- * its peer.
- */
-
-/*----- That's all, folks -------------------------------------------------*/
-
-#endif
~mdw / tripe / blobdiff