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/*
* Off-the-Record Messaging library
* Copyright (C) 2004-2008 Ian Goldberg, Chris Alexander, Nikita Borisov
* <otr@cypherpunks.ca>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of version 2.1 of the GNU Lesser General
* Public License as published by the Free Software Foundation.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __AUTH_H__
#define __AUTH_H__
#include <gcrypt.h>
#include "dh.h"
typedef enum {
OTRL_AUTHSTATE_NONE,
OTRL_AUTHSTATE_AWAITING_DHKEY,
OTRL_AUTHSTATE_AWAITING_REVEALSIG,
OTRL_AUTHSTATE_AWAITING_SIG,
OTRL_AUTHSTATE_V1_SETUP
} OtrlAuthState;
typedef struct {
OtrlAuthState authstate; /* Our state */
DH_keypair our_dh; /* Our D-H key */
unsigned int our_keyid; /* ...and its keyid */
unsigned char *encgx; /* The encrypted value of g^x */
size_t encgx_len; /* ...and its length */
unsigned char r[16]; /* The encryption key */
unsigned char hashgx[32]; /* SHA256(g^x) */
gcry_mpi_t their_pub; /* Their D-H public key */
unsigned int their_keyid; /* ...and its keyid */
gcry_cipher_hd_t enc_c, enc_cp; /* c and c' encryption keys */
gcry_md_hd_t mac_m1, mac_m1p; /* m1 and m1' MAC keys */
gcry_md_hd_t mac_m2, mac_m2p; /* m2 and m2' MAC keys */
unsigned char their_fingerprint[20]; /* The fingerprint of their
long-term signing key */
int initiated; /* Did we initiate this
authentication? */
unsigned int protocol_version; /* The protocol version number
used to authenticate. */
unsigned char secure_session_id[20]; /* The secure session id */
size_t secure_session_id_len; /* And its actual length,
which may be either 20 (for
v1) or 8 (for v2) */
OtrlSessionIdHalf session_id_half; /* Which half of the session
id gets shown in bold */
char *lastauthmsg; /* The last auth message
(base-64 encoded) we sent,
in case we need to
retransmit it. */
} OtrlAuthInfo;
#include "privkey-t.h"
/*
* Initialize the fields of an OtrlAuthInfo (already allocated).
*/
void otrl_auth_new(OtrlAuthInfo *auth);
/*
* Clear the fields of an OtrlAuthInfo (but leave it allocated).
*/
void otrl_auth_clear(OtrlAuthInfo *auth);
/*
* Start a fresh AKE (version 2) using the given OtrlAuthInfo. Generate
* a fresh DH keypair to use. If no error is returned, the message to
* transmit will be contained in auth->lastauthmsg.
*/
gcry_error_t otrl_auth_start_v2(OtrlAuthInfo *auth);
/*
* Handle an incoming D-H Commit Message. If no error is returned, the
* message to send will be left in auth->lastauthmsg. Generate a fresh
* keypair to use.
*/
gcry_error_t otrl_auth_handle_commit(OtrlAuthInfo *auth,
const char *commitmsg);
/*
* Handle an incoming D-H Key Message. If no error is returned, and
* *havemsgp is 1, the message to sent will be left in auth->lastauthmsg.
* Use the given private authentication key to sign messages.
*/
gcry_error_t otrl_auth_handle_key(OtrlAuthInfo *auth, const char *keymsg,
int *havemsgp, OtrlPrivKey *privkey);
/*
* Handle an incoming Reveal Signature Message. If no error is
* returned, and *havemsgp is 1, the message to be sent will be left in
* auth->lastauthmsg. Use the given private authentication key to sign
* messages. Call the auth_succeeded callback if authentication is
* successful.
*/
gcry_error_t otrl_auth_handle_revealsig(OtrlAuthInfo *auth,
const char *revealmsg, int *havemsgp, OtrlPrivKey *privkey,
gcry_error_t (*auth_succeeded)(const OtrlAuthInfo *auth, void *asdata),
void *asdata);
/*
* Handle an incoming Signature Message. If no error is returned, and
* *havemsgp is 1, the message to be sent will be left in
* auth->lastauthmsg. Call the auth_succeeded callback if
* authentication is successful.
*/
gcry_error_t otrl_auth_handle_signature(OtrlAuthInfo *auth,
const char *sigmsg, int *havemsgp,
gcry_error_t (*auth_succeeded)(const OtrlAuthInfo *auth, void *asdata),
void *asdata);
/*
* Start a fresh AKE (version 1) using the given OtrlAuthInfo. If
* our_dh is NULL, generate a fresh DH keypair to use. Otherwise, use a
* copy of the one passed (with the given keyid). Use the given private
* key to sign the message. If no error is returned, the message to
* transmit will be contained in auth->lastauthmsg.
*/
gcry_error_t otrl_auth_start_v1(OtrlAuthInfo *auth, DH_keypair *our_dh,
unsigned int our_keyid, OtrlPrivKey *privkey);
/*
* Handle an incoming v1 Key Exchange Message. If no error is returned,
* and *havemsgp is 1, the message to be sent will be left in
* auth->lastauthmsg. Use the given private authentication key to sign
* messages. Call the auth_secceeded callback if authentication is
* successful. If non-NULL, use a copy of the given D-H keypair, with
* the given keyid.
*/
gcry_error_t otrl_auth_handle_v1_key_exchange(OtrlAuthInfo *auth,
const char *keyexchmsg, int *havemsgp, OtrlPrivKey *privkey,
DH_keypair *our_dh, unsigned int our_keyid,
gcry_error_t (*auth_succeeded)(const OtrlAuthInfo *auth, void *asdata),
void *asdata);
#endif
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