Java PGP

From Foochal

Contents 1 How to use PGP or GPG from Java 2 Quick tutorial on using Gnu PGP, or PGP from command line 2.1 Generating your PGP keys 2.2 Encrypting a file 2.3 Decrypting a file

How to use PGP or GPG from Java

This article describes how to use PGP encryption and decryption from your java programs

Quick tutorial on using Gnu PGP, or PGP from command line

Generating your PGP keys

Generate your keys in custom directory (default is USER_HOME/.gnupg).

$ GPG_DIR=gpgdir
$ mkdir $GPG_DIR
$ gpg --gen-key --homedir $GPG_DIR

Use the following inputs:

kind of key

RSA (sign only)

Key is valid for?

(0)

Is this correct? (y/N)

y

Real name

Foochal

Email address

foochal@foochal.org

Comment

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit?

O

You need a Passphrase to protect your secret key.

change this -> my secret passphrase <- change this

Encrypting a file

GPG=/usr/bin/gpg
PASSPHRASE_FILE=passphrase.txt
# gpg home directory, no trailing slash
GPG_DIR=gpgdir
ORIGINAL_FILE=secret.txt
ENCRYPTED_FILE=secret.pgp
DECRYPTED_FILE=secret.decrypted.txt
RECIPIENT_ID="Foochal <foochal@foochal.org>"

rm -f $ENCRYPTED_FILE $DECRYPTED_FILE

#encryption
$GPG --trust-model always --homedir $GPG_DIR --encrypt --batch --recipient "$RECIPIENT_ID" --output $ENCRYPTED_FILE $ORIGINAL_FILE

Decrypting a file

#decryption
cat $PASSPHRASE_FILE | $GPG --trust-model always --homedir $GPG_DIR --decrypt --batch --passphrase-fd 0 --output $DECRYPTED_FILE $ENCRYPTED_FILE

# verify that encryption and decryption were successful
diff $ORIGINAL_FILE $DECRYPTED_FILE