SSH Key Generator (Ed25519, RSA, ECDSA)

SSH keys let you log in to servers and push to Git hosts without a password. This generator creates a key pair in your browser with the Web Crypto API — Ed25519 by default, or RSA and ECDSA — and writes it in the same OpenSSH format ssh-keygen uses, with the public authorized_keys line, the SHA256 fingerprint and the randomart picture. Inspect mode reads any public key and shows its type, size and fingerprints.

How to use this tool

1. Choose Generate and a key type (Ed25519 unless an old system needs RSA).
2. Enter a comment such as you@laptop and press the button.
3. Save the private key as ~/.ssh/id_ed25519 (permissions 600) and the public line as id_ed25519.pub.
4. Add a passphrase with ssh-keygen -p, then paste the public line into the server’s authorized_keys or your Git host’s SSH settings.

Formula

Fingerprint = "SHA256:" + Base64(SHA-256(key blob)), without "=" padding. The key blob is the Base64 part of the public line: the type name and key values as SSH strings (RFC 4251).

Ed25519 keys are always 256 bits. RSA keys should be at least 3072 bits for new use (2048 is the minimum). The randomart is the "drunken bishop" walk over the fingerprint bytes that ssh-keygen -lv prints.

Example

The public key ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIERM…sdYd alice@example.com is a 256-bit Ed25519 key with fingerprint SHA256:cRBBc7CziesFBOrh1K5rdP6erHjfjhy5CynfWm9pdqk — exactly what ssh-keygen -lf prints for it.