SSH-KEYSIGN(8) System Manager's Manual SSH-KEYSIGN(8)

# [NAME](#NAME)

`ssh-keysign` — OpenSSH helper for host-based authentication

# [SYNOPSIS](#SYNOPSIS)

`ssh-keysign`

# [DESCRIPTION](#DESCRIPTION)

`ssh-keysign` is used by [ssh(1)](/man/os/openssh/ssh.1) to access the local host keys and generate the digital signature required during host-based authentication.

`ssh-keysign` is disabled by default and can only be enabled in the global client configuration file /etc/ssh/ssh\_config by setting `EnableSSHKeysign` to “yes”.

`ssh-keysign` is not intended to be invoked by the user, but from [ssh(1)](/man/os/openssh/ssh.1). See [ssh(1)](/man/os/openssh/ssh.1) and [sshd(8)](/man/os/openssh/sshd.8) for more information about host-based authentication.

# [FILES](#FILES)

/etc/ssh/ssh\_config

Controls whether `ssh-keysign` is enabled.

/etc/ssh/ssh\_host\_ecdsa\_key

 

/etc/ssh/ssh\_host\_ed25519\_key

 

/etc/ssh/ssh\_host\_mldsa44\_ed25519\_key

 

/etc/ssh/ssh\_host\_rsa\_key

These files contain the private parts of the host keys used to generate the digital signature. They should be owned by root, readable only by root, and not accessible to others. Since they are readable only by root, `ssh-keysign` must be set-uid root if host-based authentication is used.

/etc/ssh/ssh\_host\_ecdsa\_key-cert.pub

 

/etc/ssh/ssh\_host\_ed25519\_key-cert.pub

 

/etc/ssh/ssh\_host\_mldsa44\_ed25519\_key-cert.pub

 

/etc/ssh/ssh\_host\_rsa\_key-cert.pub

If these files exist, they are assumed to contain public certificate information corresponding with the private keys above.

# [SEE ALSO](#SEE_ALSO)

[ssh(1)](/man/os/openssh/ssh.1), [ssh-keygen(1)](/man/os/openssh/ssh-keygen.1), [ssh\_config(5)](/man/os/openssh/ssh_config.5), [sshd(8)](/man/os/openssh/sshd.8)

# [HISTORY](#HISTORY)

`ssh-keysign` first appeared in OpenBSD 3.2.

# [AUTHORS](#AUTHORS)

Markus Friedl <[markus@openbsd.org](mailto:markus@openbsd.org)>

July 10, 2026 Linux 4.19.0-gvisor

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Document: ssh-keysign(8) from openssh 10.6_p1-r0 (Chainguard OS)
Source: https://github.com/openssh/openssh-portable