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https://issues.apache.org/jira/browse/SSHD-1216?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17429237#comment-17429237
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Evgeny Pasynkov commented on SSHD-1216:
---------------------------------------

Completely agree with you, this solution is temporary and may be used only 
until "official" support appears in MINA core.

And additional thanks to `ext-info-c`. There are still exist solutions which 
use old jsch, which doesn't support extensions

> Implement RFC 8332 server-sig-algs on the server
> ------------------------------------------------
>
>                 Key: SSHD-1216
>                 URL: https://issues.apache.org/jira/browse/SSHD-1216
>             Project: MINA SSHD
>          Issue Type: Improvement
>            Reporter: Ben Humphreys
>            Priority: Major
>
> In the recently released [OpenSSH 
> 8.8|https://www.openssh.com/txt/release-8.8] for RSA keys the public key 
> signature algorithm that depends on SHA-1 has been disabled by default:
> {quote}This release disables RSA signatures using the SHA-1 hash algorithm 
> 2by default. This change has been made as the SHA-1 hash algorithm is 
> cryptographically broken, and it is possible to create chosen-prefix 4hash 
> collisions for <USD$50K [1]
> {quote}
> As a result OpenSSH 8.8 clients are unable to authenticate with Mina SSHD 
> servers with RSA based keys (it is however possible to reenable ssh-rsa). 
> OpenSSH since 7.2 does however support RFC 8332 RSA/SHA-256/512 signatures, 
> indeed the release notes go on to say:
> {quote}
> For most users, this change should be invisible and there is no need to 
> replace ssh-rsa keys. OpenSSH has supported RFC8332 RSA/SHA-256/512 
> signatures since release 7.2 and existing ssh-rsa keys will automatically use 
> the stronger algorithm where possible.
> {quote}
> It appears Mina SSHD partly implements support for RFC 8332, indeed the 
> client code appears to support it (see SSHD-1141). However the server appears 
> to lack full support because it doesn't full implement the"server-sig-algs" 
> extension.
> The basic framework for supporting this seems to be present, specifically 
> {{AbstractKexFactoryManager.setKexExtensionHandler()}} could perhaps permit 
> such a "server-sig-algs" extension.
>  



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