change default keygen key type

[tgauth]

PR Summary

• change default key type to ecdsa

[panekj]

What is the reason to downgrade from better key type to the NIST one, especially since ECDSA isn't popular choice at all?

[tgauth]

What is the reason to downgrade from better key type to the NIST one, especially since ECDSA isn't popular choice at all?

OpenSSH's ed25519 is currently hardcoded to OpenSSH's implementation, rather than being routed to OpenSSL, making it much harder to FIPS certify.
As far as CNSA (https://media.defense.gov/2022/Sep/07/2003071834/-1/-1/0/CSA_CNSA_2.0_ALGORITHMS_.PDF) is concerned, the recent update of default key from RSA 3072 to ed25519 was a downgrade, and the equivalent ECC-based signature should be at least ECDSA P-384.