github-ssh-keys
Installation
SKILL.md
GitHub SSH Keys
Prefer Ed25519. GitHub dropped DSA on 2022-03-15; RSA keys created after 2021-11-02 must sign with SHA-2 (rsa-sha2-256 / rsa-sha2-512). Fall back to RSA-4096 only when the target genuinely cannot handle Ed25519.
Algorithm choice
| Key type | When |
|---|---|
ed25519 |
default; all modern systems |
rsa -b 4096 |
legacy servers without Ed25519 |
ed25519-sk |
FIDO2/U2F hardware key |
ecdsa-sk |
hardware key whose firmware lacks Ed25519 |
The _sk file on disk is a handle, not the key. Physical device lost = key lost.