Proton AG An OpenPGP user may want to request their email provider to automatically forward some or all of the messages they receive to a third party. Given that messages are encrypted, this requires transforming them into ciphertexts decryptable by the intended forwarded parties, while maintaining confidentiality and authentication. This can be achieved using Proxy transformations on the Curve25519 elliptic curve field with minimal changes to the OpenPGP protocol, in particular no change is required on the sender side. In this document we implement the forwarding scheme described in [FORWARDING].