SSH Implementation Comparison
ssh-comparison.quendi.de
ssh-comparison.quendi.de
This would be sort-of a sub-feature of the publickey authentication feature. Because the Security Key is responsible for actually signing stuff, and it has no interest in the SSH protocol per se, the SSH client and server need custom handling for this case.
Sightly unrelated, but the choice of many ciphers that can be added and deprecated over time is a great feature.
There is a wave of single purpose tools that by design only support one and only one cipher (such as age and minisign). These tools will eventually be forcefully obsolete or become the thing they hate.
Imagine if ssh or tls was hard coded to a single cipher and you needed to change tools every 5-10 years.
- The original SSH and it's commercial competitors. Some abandoned, some still surviving.
- Various open source implementations. OpenSSH and PuTTY were the winners (PuTTY actually was released first). But there were more attempts (e.g. lsh).
- Those early open source implementations were designed as stand-alone programs (clients and servers). So you have a later wave of library implementations. With of course at least one per language.