comparing-ssh-keys

[-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa]

FIDO2-Based SSH Keys (ed25519-sk and ecdsa-sk)

The sk extension stands for security key.

ssh-keygen -t ecdsa-sk
Generating public/private ecdsa-sk key pair.
You may need to touch your authenticator to authorize key generation.
Key enrollment failed: invalid format

what is fido2 security key

• https://learn.microsoft.com/en-us/azure/active-directory/authentication/concept-authentication-passwordless#fido2-security-keys
• https://www.yubico.com/authentication-standards/fido2/

recommendation of Generating SSH Key File in Linux

ssh-keygen -t ed25519


## Invalid RSA key length: maximum is 16384 bits
ssh-keygen -t rsa -b 4096 


## Invalid ECDSA key length: valid lengths are 256, 384 or 521 bits
ssh-keygen -t ecdsa -b 521

ref

• What is the -sk ending for ssh key types?
• SSH Key type ed25519-sk (and ecdsa-sk)
• Comparing SSH Keys – RSA, DSA, ECDSA, or EdDSA?
• FIDO2-Based SSH Keys (ed25519-sk and ecdsa-sk)
• Does SSH key with type ecdsa-sk or ed25519-sk need passphrase?
• ssh key类型这么多，要如何选择呢？
• GitHub 支援 SSH 使用 Security Key 了
• How to know the SSH key’s length?