ed25519brute brute-forces ed25519 public key with a given authorized key suffix or fingerprint prefix/suffix.
Here is an example of ed25519 public key with authorized key prefix of A, fingerprint prefix of A, and suffix of A.
% cat out.pub
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIGFFEo+qnsDoIo8DyNMgr1HoqPM89yMc6mrzWdFIc4vA
% ssh-keygen -l -f out
256 SHA256:AEV1jYsPpgx6Gqik2Z4NMOUHVUc/mRD6aGGCyaSTxAA out.pub (ED25519)
$ ed25519brute -authorized-key-suffix test
2024/03/20 20:37:56 start
2024/03/20 20:38:05 found
% cat out.pub
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAINynu9CvEi6Yav1Y2L7hNxtD63RiHZkOG/ZsVzsNtest
% ed25519brute -fingerprint-prefix hello
2024/03/20 20:39:54 start
2024/03/20 21:22:53 found
% ssh-keygen -l -f out
256 SHA256:helloz8d+urX+JvZmOVdewcWAx89vXeoKTLsUH0mgBc out.pub (ED25519)
$ ed25519brute -fingerprint-suffix KEY
2024/03/20 21:23:11 start
2024/03/20 21:23:11 found
% ssh-keygen -l -f out
256 SHA256:8qN1j+/pE1VFyPzIzi6S9Njqvwtw52PIQJqCj9K8KEY out.pub (ED25519)