.Dd February 1, 2023
.Dt DROPBEARKEY 1
.Os
.Sh NAME
.Nm dropbearkey
.Nd create private keys for the use with
.Xr dropbear 8
or
.Xr dbclient 1
.Sh SYNOPSIS
.Nm
.Fl t
.Ar type
.Fl f
.Ar file
.Op Fl s Ar bits
.Op Fl y
.Sh DESCRIPTION
.Nm dropbearkey
generates a
.Dv RSA , DSS , ECDSA ,
or
.Dv Ed25519
format SSH private key, and saves it to a file for the use with the
Dropbear client or server.
Note that
some SSH implementations
use the term
.Dq DSA
rather than
.Dq DSS ,
they mean the same thing.
.Sh OPTIONS
.Bl -tag -width Ds
.It Fl t Ar type
Type of key to generate.
Must be one of
.Cm rsa ,
.Cm ecdsa ,
.Cm ed25519 ,
or
.Cm dss .
.It Fl f Ar file
Write the secret key to the file
.Ar file .
For client authentication
.Pa ~/.ssh/id_dropbear
is loaded by default
.It Fl s Ar bits
Set the key size to
.Ar bits
bits, should be multiple of 8 (optional).
.It Fl y
Just print the publickey and fingerprint for the private key in
.Ar file .
.El
.Sh NOTES
The program
.Xr dropbearconvert 1
can be used to convert between Dropbear and OpenSSH key formats.
.Pp
Dropbear does not support encrypted keys.
.Sh EXAMPLES
generate a host-key:
.Bd -literal -offset indent
# dropbearkey -t rsa -f /etc/dropbear/dropbear_rsa_host_key
.Ed
.Pp
extract a public key suitable for
.Pa authorized_keys
from private key:
.Bd -literal -offset indent
# dropbearkey -y -f id_rsa | grep "^ssh-rsa " >> authorized_keys
.Ed
.Sh SEE ALSO
.Xr dbclient 1 ,
.Xr dropbearconvert 1 ,
.Xr dropbear 8
.Pp
.Lk https://matt.ucc.asn.au/dropbear/dropbear.html
.Sh AUTHORS
.An Matt Johnston Aq Mt matt@ucc.asn.au .
.An Gerrit Pape Aq Mt pape@smarden.org
wrote this manual page.