SSH public-key fingerprint
Calculate a SHA256 fingerprint from an OpenSSH RSA or Ed25519 public-key blob and validate its wire structure.
- 1Add input
- 2Adjust settings
- 3Get your result
Tool input and files are processed in this browser without being uploaded.
Before you start
Calculate the full SHA256 fingerprint of one OpenSSH RSA or Ed25519 public key. Paste a .pub key, then optionally compare it with a trusted SHA256 fingerprint displayed elsewhere.
How to use this tool
- Paste one OpenSSH public key beginning with ssh-ed25519 or ssh-rsa, or choose a .pub file.
- Optionally enter the complete SHA256: fingerprint shown by a trusted service.
- Inspect the full calculated fingerprint and exact match result; a matching comment alone proves nothing.
Supported inputs and limits
One OpenSSH RSA or Ed25519 public key per run. Private keys, SSH certificates, other algorithms and multiline key lists are rejected. Comments are excluded from the fingerprint.
The optional expected value must be a complete, unpadded SHA256: fingerprint from a trusted source. This page cannot verify GitHub account ownership or SSH access.
Public-key input stays in the browser. A pasted key or one UTF-8 .pub/.txt file is limited to 1 MiB. Outputs do not overwrite original files.
Worked example
Example input
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIAABAgMEBQYHCAkKCwwNDg8QERITFBUWFxgZGhscHR4f demo
Example options
{"expected": ""}Example output
{
"type": "ssh-ed25519",
"fingerprint": "SHA256:ZkAslGjFiUHdGf/WUL8rQvkib4PTvQatUV0OUQSncCA",
"expectedChecked": false,
"expectedMatched": null
}When something does not work
Use one complete OpenSSH .pub line. Verify the key type, base64 data, and full expected SHA256: value; do not paste a private key or a key list.
Frequently asked questions
Which SSH public-key types are supported?
One OpenSSH ssh-ed25519 or ssh-rsa public key. The key blob is parsed before its SHA256 fingerprint is calculated; private keys and certificates are not accepted.
What should the example produce?
The sample fingerprint is SHA256:ZkAslGjFiUHdGf/WUL8rQvkib4PTvQatUV0OUQSncCA. Changing only its comment does not change the fingerprint.
Which cases are outside its scope?
This page cannot retrieve a key from GitHub, verify who owns it, or test an SSH connection. Compare with the complete SHA256 value from a trusted channel.
Documentation & further reading
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