openssh/myproposal.h
djm@openbsd.org 0051381a8c
upstream: Turn off finite field (a.k.a modp) Diffie-Hellman key
exchange in sshd by default. Specifically, this removes the
diffie-hellman-group* and diffie-hellman-group-exchange-* methods. The client
is unchanged and continues to support these methods by default.

Finite field Diffie Hellman is slow and computationally expensive for
the same security level as Elliptic Curve DH or PQ key agreement while
offering no redeeming advantages.

ECDH has been specified for the SSH protocol for 15 years and some
form of ECDH has been the default key exchange in OpenSSH for the last
14 years.

ok markus@

OpenBSD-Commit-ID: 4e238ad480a33312667cc10ae0eb6393abaec8da
2024-10-14 09:21:07 +11:00

119 lines
3.7 KiB
C

/* $OpenBSD: myproposal.h,v 1.74 2024/10/06 23:37:17 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#define KEX_SERVER_KEX \
"sntrup761x25519-sha512," \
"sntrup761x25519-sha512@openssh.com," \
"mlkem768x25519-sha256," \
"curve25519-sha256," \
"curve25519-sha256@libssh.org," \
"ecdh-sha2-nistp256," \
"ecdh-sha2-nistp384," \
"ecdh-sha2-nistp521" \
#define KEX_CLIENT_KEX KEX_SERVER_KEX "," \
"diffie-hellman-group-exchange-sha256," \
"diffie-hellman-group16-sha512," \
"diffie-hellman-group18-sha512," \
"diffie-hellman-group14-sha256"
#define KEX_DEFAULT_PK_ALG \
"ssh-ed25519-cert-v01@openssh.com," \
"ecdsa-sha2-nistp256-cert-v01@openssh.com," \
"ecdsa-sha2-nistp384-cert-v01@openssh.com," \
"ecdsa-sha2-nistp521-cert-v01@openssh.com," \
"sk-ssh-ed25519-cert-v01@openssh.com," \
"sk-ecdsa-sha2-nistp256-cert-v01@openssh.com," \
"rsa-sha2-512-cert-v01@openssh.com," \
"rsa-sha2-256-cert-v01@openssh.com," \
"ssh-ed25519," \
"ecdsa-sha2-nistp256," \
"ecdsa-sha2-nistp384," \
"ecdsa-sha2-nistp521," \
"sk-ssh-ed25519@openssh.com," \
"sk-ecdsa-sha2-nistp256@openssh.com," \
"rsa-sha2-512," \
"rsa-sha2-256"
#define KEX_SERVER_ENCRYPT \
"chacha20-poly1305@openssh.com," \
"aes128-ctr,aes192-ctr,aes256-ctr," \
"aes128-gcm@openssh.com,aes256-gcm@openssh.com"
#define KEX_CLIENT_ENCRYPT KEX_SERVER_ENCRYPT
#define KEX_SERVER_MAC \
"umac-64-etm@openssh.com," \
"umac-128-etm@openssh.com," \
"hmac-sha2-256-etm@openssh.com," \
"hmac-sha2-512-etm@openssh.com," \
"hmac-sha1-etm@openssh.com," \
"umac-64@openssh.com," \
"umac-128@openssh.com," \
"hmac-sha2-256," \
"hmac-sha2-512," \
"hmac-sha1"
#define KEX_CLIENT_MAC KEX_SERVER_MAC
/* Not a KEX value, but here so all the algorithm defaults are together */
#define SSH_ALLOWED_CA_SIGALGS \
"ssh-ed25519," \
"ecdsa-sha2-nistp256," \
"ecdsa-sha2-nistp384," \
"ecdsa-sha2-nistp521," \
"sk-ssh-ed25519@openssh.com," \
"sk-ecdsa-sha2-nistp256@openssh.com," \
"rsa-sha2-512," \
"rsa-sha2-256"
#define KEX_DEFAULT_COMP "none,zlib@openssh.com"
#define KEX_DEFAULT_LANG ""
#define KEX_CLIENT \
KEX_CLIENT_KEX, \
KEX_DEFAULT_PK_ALG, \
KEX_CLIENT_ENCRYPT, \
KEX_CLIENT_ENCRYPT, \
KEX_CLIENT_MAC, \
KEX_CLIENT_MAC, \
KEX_DEFAULT_COMP, \
KEX_DEFAULT_COMP, \
KEX_DEFAULT_LANG, \
KEX_DEFAULT_LANG
#define KEX_SERVER \
KEX_SERVER_KEX, \
KEX_DEFAULT_PK_ALG, \
KEX_SERVER_ENCRYPT, \
KEX_SERVER_ENCRYPT, \
KEX_SERVER_MAC, \
KEX_SERVER_MAC, \
KEX_DEFAULT_COMP, \
KEX_DEFAULT_COMP, \
KEX_DEFAULT_LANG, \
KEX_DEFAULT_LANG