What is an SSH Ed25519 Key? (And Why You Should Use It)

When generating a new SSH key to connect to GitHub, AWS, or your personal server, you are usually prompted to choose an algorithm. For a long time, RSA was the default. Today, Ed25519 is the modern standard.

What is Ed25519?

Ed25519 is a public-key signature system that uses the EdDSA (Edwards-curve Digital Signature Algorithm) and relies on the Curve25519 elliptic curve.

It was introduced to OpenSSH in version 6.5 (released in 2014) and has since become the universally recommended standard for SSH keys.

Advantages over RSA

1. More Secure: Ed25519 provides stronger mathematical security against both current and future cryptographic attacks compared to standard RSA keys.
2. Faster: It is significantly faster to generate, sign, and verify signatures compared to RSA. This makes SSH connections noticeably snappier.
3. Shorter Keys: An Ed25519 public key is much shorter (only 68 characters) than a standard RSA key (which can be over 700 characters). This makes it much easier to copy and paste into authorized_keys files or web interfaces like GitHub.

How to Generate One

You can generate an Ed25519 key on your local machine using the following terminal command:

ssh-keygen -t ed25519 -C "your_email@example.com"

If you are dealing with legacy systems that do not support Ed25519, the fallback recommendation is a 4096-bit RSA key (ssh-keygen -t rsa -b 4096).

You can easily configure the perfect ssh-keygen command using our SSH Key Generator.