SSH public key fingerprint

Calculate the MD5 and SHA-256 fingerprint of an SSH public key, to verify that a server or repository is using the key you expect.

Example:

How it works

An SSH public key is a long base64 block that is hard to compare visually. Its fingerprint (a short hash calculated from the key) lets you verify it quickly: it's exactly what appears when an SSH connection asks you to confirm the authenticity of an unknown host ("The authenticity of host ... can't be established"), or what GitHub/GitLab display when you add a new deploy key.

Which fingerprint should I compare, MD5 or SHA-256?

Recent versions of OpenSSH display the SHA-256 fingerprint by default ("SHA256:..." format). The MD5 format (colons between hexadecimal pairs) was the old standard and is still used by some older tools. Compare the one that matches the format shown by your client or service.

What should I do if the fingerprint doesn't match the expected one?

Don't continue with the connection: a fingerprint that differs from the expected one may indicate a "man-in-the-middle" attack or a server key that changed legitimately (reinstall, migration). Check with the server administrator before continuing.

100% local processing: the calculation is done entirely in your browser via WebAssembly, and the pasted key is never sent to a server.