SSH Key Generator
Generate RSA or Ed25519 SSH key material for testing.
Overview
The SSH key generator produces an RSA or Ed25519 key pair in OpenSSH format. Pick a type, set an optional comment, and the tool returns both the private key (-----BEGIN OPENSSH PRIVATE KEY-----) and the matching public key (ssh-rsa AAAA... or ssh-ed25519 AAAA...) ready to drop into ~/.ssh/authorized_keys.
It is built for engineers spinning up a throwaway SSH key for a lab VM, integration tests that need a known key pair, or CI configurations where committing a static dev key into the repo is the path of least resistance. Production SSH keys still belong on a YubiKey or in ssh-agent with strong passphrase protection.
How it works
OpenSSH keys are encoded in a SSH-specific format described in PROTOCOL.key. The public key is <algorithm> <base64-blob> <comment>, where the base64 blob is a length-prefixed concatenation of the algorithm name and the key parameters (modulus and exponent for RSA, the 32-byte public point for Ed25519). The private key is wrapped in the OpenSSH "new" format introduced in 2014: a magic string openssh-key-v1, encryption metadata, the private-key payload, and an optional pass-phrase-protected bcrypt_pbkdf derived key. The whole binary blob is base64-encoded and PEM-wrapped.
For RSA, the tool generates a fresh prime pair as in the RSA generator; for Ed25519, it generates a 32-byte seed via the browser's CSPRNG and computes the public point via the curve25519 base-point multiplication.
Examples
Type: Ed25519
Comment: ci@build-server
Output:
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIK2lvZmVxcml... ci@build-server
-----BEGIN OPENSSH PRIVATE KEY-----
b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAA...
-----END OPENSSH PRIVATE KEY-----
Type: RSA 4096
Comment: lab-jumphost
Output: ssh-rsa AAAA... lab-jumphost + PEM private key (~3.4 KB)
Type: Ed25519
Comment: ""
Output: public + private without trailing comment
FAQ
Ed25519 or RSA?
Ed25519 for new keys: shorter, faster, no parameter choices to get wrong. RSA only when you must support an old server that does not understand Ed25519 — those are rare in 2026.
Is the private key encrypted?
By default, no. To add a passphrase, run ssh-keygen -p -f keyfile after dropping the key on disk. The OpenSSH format encrypts with bcrypt_pbkdf using AES-256-CTR.
How do I install it on a server?
Append the public key (the single ssh-ed25519 AAAA... comment line) to the target user's ~/.ssh/authorized_keys. Make sure the file is mode 600 and the .ssh directory is mode 700.
Is browser-side key generation safe?
For dev keys, yes — the CSPRNG is cryptographically sound and nothing leaves your browser. For production keys protecting real infrastructure, generate them in a dedicated machine you trust (ideally hardware-backed) and never paste them into a web tool.