Here are some notes that will help you get started quickly with
BouncyCastle and PGP

BouncyCastle is a JCE (Java Cryptographic Extension)-compatible
library that also handles PGP. It is well regarded. The source is not
well formatted or commented. The JavaDoc is sparce and inaccurate.

You will want to download the BouncyCastle jars for:
JCE Provider
open PGP
test examples
Java Source for Open PGP

Put the jars in your ext directory.

Generating Keys

Generate a binary private/public key with:

java org.bouncycastle.openpgp.examples.RSAKeyPairGenerator charlie
"open sesame"

The public and private keys will appear as pub.bpg, and secret.bpg.
You can generate ascii *.asc ascii armoured file instead by using the
-a option like this:

java org.bouncycastle.openpgp.examples.RSAKeyPairGenerator -a charlie
"open sesame"

To generate variants look at the source code in bcpg-jdk14-122/src/
org/bouncycastleopenpgp/examples/RSAKeyPairGenerator.java

Signing A Binary File

java org.bouncycastle.openpgp.examples.SignedFileProcessor -s
anyfile.dat secret.bpg "open sesame"

Resulting signed file will appear in anyfile.dat.bpg signed, but not
encrypted.

Verifying a Signed Binary File

java org.bouncycastle.openpgp.examples.SignedFileProcessor -v
anyfile.dat.bpg pub.bpg

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