Ed25519 verify
Check a file against an Ed25519 signature, on your device.
Ed25519 verify unwraps a public key from its fixed PEM header and checks your hex signature against the file with the noble curves library, printing valid or invalid. Any failure during verification, not only a mismatch, is reported as invalid too. A match only proves the signature and that public key agree; who holds the matching private key is outside its scope.
Questions
What inputs does it need?
The original file, the hex signature, and the SPKI public key in PEM, matching the key that signed it.
What does it print?
One word, valid or invalid, and nothing else, so a script or a person reads the result at a glance.
What happens if the signature is malformed?
Any failure during verification, not only a genuine mismatch, is reported as invalid.
Does valid tell me who signed it?
No, it only confirms the signature matches that specific public key; it says nothing about who controls that key.
Can I use this from the command line?
Yes, the same code runs on the page, the CLI and MCP.