Switching from an RSA SSH Key to Ed25519 on Ubuntu 22.04

Solve an SSH permission denied public key error (no mutual signature algorithm supported).

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0:00 -- Intro
0:35 -- Ubuntu 22.04 doesn't support RSA based SSH keys out of the box
1:04 -- What is Ed25519?
2:04 -- Encountering and debugging the permission denied SSH error
3:41 -- Seeing what type of RSA key you have with ssh-keygen
4:35 -- We have a couple of options and they can be used together
6:29 -- Updating your keys without locking yourself out
7:32 -- Ed25519 vs ECDSA
8:34 -- Ed25519 works with OpenSSH 6.5+
9:35 -- Generating a new Ed25519 SSH key
11:47 -- Copying your new key to your server's authorized_keys file

[nnutipa]

thanks man, it's very useful as always

[MrStoenz]

the only channel i need to slow down to x.75 to understand anything.

[nadgerz]

Me: What does the 25519 in the Ed25519 ssh algorithm refer to?

chatGPT: The "25519" in the Ed25519 algorithm refers to the size of the field that is used in the calculation of the algorithm. Specifically, it is the size of a prime finite field known as GF(2^255 - 19). This field is used to define the mathematical operations that are performed in the algorithm.

Ed25519 is a public-key signature system that is based on the mathematics of elliptic curves. It is a relatively new algorithm, but it has gained popularity because of its efficiency and security. One of the key advantages of Ed25519 is that it is very fast, making it suitable for use in a variety of applications. It is also considered to be very secure, with no known vulnerabilities at this time.

[farzadmf]

I also used to not set a passphrase for my key for the same reason (needing to enter my password every time), but now I'm setting up ssh agent once when I start the terminal, enter my password, and then, in my terminal, everything is good to go