gnupg1 binary package in Ubuntu Bionic arm64

 GnuPG is GNU's tool for secure communication and data storage.
 It can be used to encrypt data and to create digital signatures.
 It includes an advanced key management facility and is compliant
 with the proposed OpenPGP Internet standard as described in RFC 4880.
 .
 The gnupg1 package provides GnuPG 1.4, the "classic" standalone,
 non-modularized version. It is provided mainly for people with the
 need to use archaic cryptographic objects like PGPv3 keys to access
 archived messages. It does not support more recent cryptographic
 primitives like ECDSA or EdDSA. Please use the gnupg package instead
 unless you know for sure that you need gnupg1.

Source package