Gpg4win
Gpg4win is an email and file encryption package for most versions of Microsoft Windows , which uses GnuPG public-key cryptography for data encryption and digital signatures . 
<triplet> Gpg4win <subj> Microsoft Windows <obj> operating system <triplet> GnuPG <subj> Microsoft Windows <obj> operating system <subj> public-key cryptography <obj> use