Duplicating a value with a maliciously edited file should be virtually impossible. No need to apologize! The post was lacking details and I apologize for that. GPG Suite seems to be the one for mac ...

In managing my own keyrings, in which I have several private-public key pairs and therefore numerous user IDs containing my name, I find it easiest to provide gpg with the entire e-mail-address ...

GnuPG, the open replacement for PGP, is an excellent tool to manage cryptographic signatures to files or e-mails for validity and integrity, as well as a tool to encrypt and decrypt sensitive files.