So I copied an SSH private key from my Linux machine to my M1 Mac. (I've attempted to do this both by uploading the cyphertext to a secrets manager as well as directly transfering the file) but when attempting to SSH to the same machine from each I can only succeed from the Linux machine.
Linux machine:
$ ssh -V
OpenSSH_8.2p1 Ubuntu-4ubuntu0.4, OpenSSL 1.1.1f 31 Mar 2020
$ md5sum id_rsa
7ed8b0c73e168ef48acc715d4c6bcf73 id_rsa
$ sha256sum id_rsa
969d0a35b36c50035881bdd2d8367b90dbff548131d5c72989d29e83b7a3aa19 id_rsa
$ ssh-keygen -l -f id_rsa
4096 SHA256:d19Ee+tlzVHitLzKuuZbdgYcnhla96ypXNtpBwrqfqE [email protected] (RSA)
$ ssh -i id_rsa [email protected]
[redacted MOTD; WORKS]
M1 Mac:
$ ssh -V
openSSH_8.6p1, LibreSSL 2.8.3
$ md5 id_rsa
MD5 (id_rsa) = 7ed8b0c73e168ef48acc715d4c6bcf73
$ shasum -a 256 id_rsa
969d0a35b36c50035881bdd2d8367b90dbff548131d5c72989d29e83b7a3aa19 id_rsa
$ ssh-keygen -l -f id_rsa
4096 SHA256:rWsP9jN2otlchh8icr/jlnZxDjEfEkngDJOoPh4RYZI [email protected] (RSA)
$ ssh -i id_rsa [email protected]
[email protected]: Permission denied (publickey).
AFAICT these private keys are identical. However for some reason ssh-keygen does not fingerprint them thesame. Even though they have identical checksums. Could this be an issue with the M1 SoC? Or is there something much more obvious happening here?