title: How to verify GPG signature with OpenSSL
body: <p>I wrote a simple cross-platform utility to verify GPG signatures using the <a href="https://www.gnupg.org/(it)/related_software/gpgme/index.html" rel="nofollow">gpgme</a>. However gpgme doesn't work very well on windows and on other platforms (e.g. osx) it requires GnuPG command line utilities installed which is a pretty heavy dependency. I looked into other openpgp libraries as well such as <a href="http://www.netpgp.com/" rel="nofollow">netgpg</a> but these are even less portable (it really has to build with mingw-w64).</p>
  
  <p>Would it be possible to implement a standalone tool to verify GPG signature using only standard libraries like openssl and zlib? From what I understand openpgp consists of standard ciphers and hash functions. What is the part that makes this so difficult that there are no good C libraries out there to do this?</p>