About SSH Key Fingerprint

Calculate the fingerprint of an SSH public key. Part of the DevTools Surf developer suite. Browse more tools in the Security / Crypto collection.

Use Cases

• Verifying SSH key identity when adding keys to remote servers
• Matching fingerprints between local keys and GitHub account keys
• Auditing authorized_keys files for unknown key fingerprints
• Confirming key fingerprints during SSH host verification prompts

Tips

• Paste your public key to calculate its SHA-256 fingerprint
• Compare fingerprints to verify key identity during SSH setup
• Use this to match keys listed in authorized_keys files

Fun Facts

• SSH was invented by Tatu Ylonen in 1995 after a password-sniffing attack on his university network in Finland.
• OpenSSH switched from MD5 to SHA-256 fingerprints by default in version 6.8, released in March 2015.
• GitHub shows SSH key fingerprints in your account settings, making this tool useful for matching local keys to your GitHub profile.

FAQ

Which hash algorithm?

SHA-256 (modern default) or MD5 (legacy). OpenSSH uses SHA-256 by default since 2015. MD5 still used by some older SSH servers.

What's the fingerprint used for?

Verifying you're connecting to the intended server. First-connect warnings show the fingerprint; compare to what the server admin published.

Public or private key?

Public. Fingerprinting a private key would be a security bug — anyone with the fingerprint could check if a key they stole matches.

Can I calculate locally?

Yes: `ssh-keygen -lf ~/.ssh/id_ed25519.pub`. The tool does the same in the browser for convenience, especially when you have a key string but not the CLI.