pgs - An easy to use CLI tool to sign email or Usenet messages with your YubiKey.

Simply create an ECCP256, ECCP384 or Ed25519 key on your YubiKey
with Yubico Authenticator in slot 9c and you are all set. :-)

Usage: pgs [OPTIONS]

Options:
  -s -p PIN          Sign message using the provided PIN
  -v                 Verify a signature
  -a -c certificate  Analyze signed message with certificate file
  -d                 Use detached signature mode

Examples:
  pgs -s -p 12345678 < msg.txt > signed.txt
  pgs -v < signed.txt
  pgs -a < signed.txt -c cert.pem
  pgs -s -p 12345678 -d signature.sig < binary_file
  pgs -v -d signature.sig < binary_file

What does pgs stand for? It is a homage to pgp and means
pretty good signer, signature, etc. you name it. :-)

Why does pgs uses only ECCP? Because old YubiKeys with old
firmware support them as well and RSA signatures are too
big for my taste.