class Capsium::Package::OpenPgpCipher

Encrypts and decrypts whole Capsium packages with OpenPGP key management (ARCHITECTURE.md section 6b) through librnp (Capsium::Package::OpenPgp). Parallel to the RSA-OAEP-SHA256 Cipher — same encrypted .cap layout, same AES-256-GCM content encryption, same typed errors — with the DEK carried as an armored OpenPGP message instead of an RSA-wrapped blob:

{"encryption": {"algorithm": "AES-256-GCM",
                "keyManagement": "OpenPGP",
                "message": <armored OpenPGP message with the DEK>,
                "iv": <base64>, "authTag": <base64>}}

Keys are OpenPGP key files (armored or binary, auto-detected): encryption needs the recipient’s public key, decryption the secret key.