Bug 34914 - enhancement request: enable openssh server post quantum encryption algorithms by default
Summary: enhancement request: enable openssh server post quantum encryption algorithms...
Status: NEW
Alias: None
Product: Mageia
Classification: Unclassified
Component: RPM Packages (show other bugs)
Version: 9
Hardware: All Linux
Priority: Normal enhancement
Target Milestone: ---
Assignee: QA Team
QA Contact:
URL: https://www.openssh.org/pq.html
Whiteboard: MGA9-64-OK
Keywords: advisory
Depends on:
Blocks:
 
Reported: 2025-12-27 21:55 CET by Paul Blackburn
Modified: 2025-12-30 18:06 CET (History)
4 users (show)

See Also:
Source RPM: crypto-policies-20221110-2.mga9
CVE:
Status comment:


Attachments

Description Paul Blackburn 2025-12-27 21:55:47 CET
Description of problem:

Saturday 27th December 2025.
reference: https://www.openssh.org/pq.html

On making ssh connection between latest Kali and Mageia 9:

┌──(user㉿kali)-[~]
└─$ ssh z600-mageia9.home
** WARNING: connection is not using a post-quantum key exchange algorithm.
** This session may be vulnerable to "store now, decrypt later" attacks.
** The server may need to be upgraded. See https://openssh.com/pq.html
(user@z600-mageia9.home) Password: 
Last login: Sun Dec 14 12:03:48 2025

# ssh client Version on Kali:

┌──(user㉿kali)-[~]
└─$ ssh -V
OpenSSH_10.2p1 Debian-3, OpenSSL 3.5.4 30 Sep 2025

# sshd server version on Kali:
┌──(user㉿kali)-[~]
└─$ apt list openssh-server
openssh-server/kali-rolling,now 1:10.2p1-3 amd64 [installed,automatic]

# openssl version on Kali:
┌──(user㉿kali)-[~]
└─$ apt list openssl       
openssl/kali-rolling,now 3.5.4-1 amd64 [installed,automatic]

Version-Release number of selected component (if applicable):

openssh-server-9.3p1-2.5.mga9

How reproducible: happens every time


Steps to Reproduce:
1.using openssh version 10, connect to a Mageia 9 sshd
2.
3.
Comment 1 Paul Blackburn 2025-12-27 21:57:14 CET
# ssh client Version  on Mageia 9:

[user@z600-mageia9 ~]$ ssh -V
OpenSSH_9.3p1, OpenSSL 3.0.18 30 Sep 2025

# sshd server version on Mageia9:

[user@z600-mageia9 ~]$ rpm -q openssh-server
openssh-server-9.3p1-2.5.mga9

# openssl version on Mageia9:

[user@z600-mageia9 ~]$ rpm -q openssl
openssl-3.0.18-1.mga9
Comment 2 Morgan Leijström 2025-12-27 23:06:19 CET
This package have been updated by various packagers, assigning all.

CC: (none) => fri
Assignee: bugsquad => pkg-bugs
Summary: enhancement request: update openssh server to version 10 for post quantun encryption algorithms => enhancement request: update openssh server to version 10 for post quantum encryption algorithms

Comment 3 Jani Välimaa 2025-12-28 16:10:04 CET
mga9 openssh already supports sntrup761x25519-sha512.

$ ssh -Q kex
diffie-hellman-group1-sha1
diffie-hellman-group14-sha1
diffie-hellman-group14-sha256
diffie-hellman-group16-sha512
diffie-hellman-group18-sha512
diffie-hellman-group-exchange-sha1
diffie-hellman-group-exchange-sha256
ecdh-sha2-nistp256
ecdh-sha2-nistp384
ecdh-sha2-nistp521
curve25519-sha256
curve25519-sha256@libssh.org
sntrup761x25519-sha512@openssh.com

Unfortunately, it's not (yet) enabled by default via crypto-policies.

# sshd -T|grep ^kexalgorithms
kexalgorithms curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512

It can be enabled manually until crypto-policies gets updated, though. Edit /etc/crypto-policies/back-ends/opensshserver.config and add  sntrup761x25519-sha512@openssh.com to KexAlgorithms, and restart sshd.

# systemctl restart sshd
# sshd -T|grep ^kexalgorithms
kexalgorithms sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512

CC: (none) => jani.valimaa

Jani Välimaa 2025-12-28 16:11:11 CET

Summary: enhancement request: update openssh server to version 10 for post quantum encryption algorithms => enhancement request: enable openssh server post quantum encryption algorithms by default

Jani Välimaa 2025-12-28 16:12:18 CET

Source RPM: openssh-server-9.3p1-2.5.mga9 => crypto-policies-20221110-2.mga9

Comment 4 Paul Blackburn 2025-12-28 18:41:27 CET
reference comment 3 (above)

Thanks Jani,

I tried your suggestion and confirm it worked for me.

I am running Mageia 9 with all updates applied.

I followed your steps:

1/ Edit /etc/crypto-policies/back-ends/opensshserver.config
2/ Locate the "KexAlgorithms" line (which is line #4 here).
3/ Append ",sntrup761x25519-sha512@openssh.com" to the KexAlgorithms line.

systemctl restart sshd.service && systemctl status sshd.service

Note: my first attempt to make this change failed because I did not put a comma separator before "sntrup761x25519-sha512@openssh.com" in
/etc/crypto-policies/back-ends/opensshserver.config

Kind regards
Cordialement
Paul
Comment 5 Jani Välimaa 2025-12-28 21:44:33 CET
This should be fixed with crypto-policies-20221110-2.1.mga9 available in core/updates_testing anytime soon.

Assignee: pkg-bugs => qa-bugs

PC LX 2025-12-29 01:57:53 CET

CC: (none) => mageia

Comment 6 Jani Välimaa 2025-12-29 18:56:17 CET
SRPMS:
crypto-policies-20221110-2.1.mga9

RPMS:
crypto-policies-20221110-2.1.mga9
crypto-policies-scripts-20221110-2.1.mga9
katnatek 2025-12-29 19:59:34 CET

Keywords: (none) => advisory

Comment 7 katnatek 2025-12-29 20:12:24 CET
sshd -T|grep ^kexalgorithms
kexalgorithms curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512


installing crypto-policies-20221110-2.1.mga9.noarch.rpm from //home/katnatek/qa-testing/x86_64
Preparing...                     ###################################################################################################
      1/1: crypto-policies       ###################################################################################################
      1/1: removing crypto-policies-20221110-2.mga9.noarch
                                 ###################################################################################################

sshd -T|grep ^kexalgorithms
kexalgorithms sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512


Looks good
Comment 8 katnatek 2025-12-29 20:17:49 CET
If the crypto-policies-scripts is a mandatory package, should crypto-policies require it?

Keywords: (none) => feedback

Comment 9 Jani Välimaa 2025-12-30 16:57:12 CET
(In reply to katnatek from comment #8)
> If the crypto-policies-scripts is a mandatory package, should
> crypto-policies require it?
It is not mandatory nor needed for this update.
Comment 10 katnatek 2025-12-30 18:06:28 CET
(In reply to Jani Välimaa from comment #9)
> (In reply to katnatek from comment #8)
> > If the crypto-policies-scripts is a mandatory package, should
> > crypto-policies require it?
> It is not mandatory nor needed for this update.

Good for me then, thank you

Whiteboard: (none) => MGA9-64-OK
CC: (none) => andrewsfarm
Keywords: feedback => (none)


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