Default Ed25519 signer using OTP :crypto.

For production use, consider implementing SigilGuard.Signer with an HSM or KMS backend instead.

Usage

Process-free, passing the signer struct explicitly:

{_pub, priv} = SigilGuard.Signer.generate_keypair()
signer = SigilGuard.Signer.Ed25519.new(priv)
signature = SigilGuard.Signer.Ed25519.sign_with(signer, message)

Or as a module-based signer (the form SigilGuard.Envelope.sign/3 expects in its :signer option) via start_link/1:

{:ok, _pid} = SigilGuard.Signer.Ed25519.start_link(private_key: priv)
signature = SigilGuard.Signer.Ed25519.sign(message)

Process Model

start_link/1 registers a singleton Agent under SigilGuard.Signer.Ed25519 holding the keypair — one keypair per node. Supervise it in your application's tree; sign/1 and public_key/0 exit if it is not running. For multiple keypairs in one node, use new/1 + sign_with/2 or implement SigilGuard.Signer in your own module.