Users have requested the capability to sign content directly with pgp in addition to storing the signature in an attribute (SignContentAttributePGP). There should be options to clearsign and armor the content. There should be an option to produce the detached signature as it's own flowfile.
Pairing with this processor, users have requested the capability to verify signed content with pgp in addition to verifying the signature in an attribute (VerifyContentAttributePGP). There should be options to verify clearsigned and armored content also.
Finally, the DecryptContentPGP processor should be able to decrypt the signed content, so that just the unsigned content remains.
These processors should use the PGPKeyMaterialService.