OpenBSD tool to sign and verify signatures on files. Portable version.

The signify utility creates and verifies cryptographic signatures.
A signature verifies the integrity of a message.

The key and signature files created by signify have the same format.
The first line of the file is a free form text comment that may
be edited, so long as it does not exceed a single line. Signature
comments will be generated based on the name of the secret key used
for signing. This comment can then be used as a hint for the name
of the public key when verifying. The second line of the file is the
actual key or signature base64 encoded.