About SSHCheck
What this is
SSH public key tools that run in your browser. Nothing you paste is uploaded.
| Tool | What it does | Limits |
|---|---|---|
| Format check (home page) | Splits the line into algorithm, data and comment and echoes them. | Does not decode the key. A damaged key can pass. |
| Key inspector | Decodes the key's wire format. Reports type, RSA or curve size, and the SHA256: fingerprint that ssh-keygen -lf prints. Warns about weak sizes, wrapped lines, a type field that disagrees with the key data, and trailing bytes. | Public keys only. |
| authorized_keys checker | Runs the inspector over every line, handles option prefixes, and finds duplicates by fingerprint. | Cannot check file ownership or permissions. |
Private keys are refused
If the text contains a PRIVATE KEY header the tools stop and say so without decoding anything. Do not paste a private key into any website; the public key is the .pub file, or ssh-keygen -y -f <keyfile> prints it.
Verified against ssh-keygen
The inspector's fingerprints are checked in this repository's tests against keys generated with ssh-keygen (ed25519, RSA 2048, ECDSA P-256 and P-521) and match its output exactly.
What no key checker can tell you
Whether the key is accepted by a particular server, GitHub account or authorized_keys file, or whether its private half is protected by a passphrase.