TIL: a mildly interesting trick -- signing a file with ssh public key:

$ < content.txt ssh-keygen -Y sign -n file -f ~/.ssh/id_ed25519.pub > content.txt.sig
Signing data on standard input


To verify the file:

$ < content.txt ssh-keygen -Y check-novalidate -n file -f ~/.ssh/id_ed25519.pub -s content.txt.sig
Good "file" signature with ED25519 key SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx