Pretty Curved Privacy 0.3.0

Pretty Curved Privacy (pcp1) is a commandline utility which can be used to encrypt files. pcp1 uses eliptc curve cryptography for encryption (CURVE25519 by Dan J. Bernstein). While CURVE25519 is no worldwide accepted standard it hasn't been compromised by the NSA - which might be better, depending on your point of view.

Caution: since CURVE25519 is no accepted standard, pcp1 has to be considered as experimental software. In fact, I wrote it just to learn about the curve and see how it works.

Beside some differences it works like GNUPG. So, if you already know how to use gpg, you'll feel almost home.

Quick Start

Lets say, Alicia and Bobby want to exchange encrypted messages. Here's what the've got to do.

First, both have create a secret key:

Alicia Bobby pcp1 -k pcp1 -k

After entering their name, email address and a passphrase to protect the key, it will be stored in their vault file (by default ~/.pcpvault).

Now, both of them have to export the public key, which has to be imported by the other one. With pcp you can export the public part of your primary key, but the better solution is to export a derived public key especially for the recipient:

Alicia Bobby pcp1 -p -r Bobby -O pcp1 -p -r Alicia -O

They've to exchange the public key somehow (which is not my problem at the moment, use ssh, encrypted mail, whatever).

Once exchanged, they have to import it:

Alicia Bobby pcp1 -P -I pcp1 -P -I

They will see a response as this when done:

key 0x29A323A2C295D391 added to .pcpvault.

Now, Alicia finally writes the secret message, encrypts it and sends it to Bobby, who in turn decrypts it:

Alicia Bobby echo "Love you, honey" > letter pcp1 -e -i 0x29A323A2C295D391 -I letter -O letter.z85 cat letter.z85 | mail

                                    pcp1 -d -I letter.z85 | less

And that's it.

Please note the big difference to GPG though: both Alicia AND Bobby have to enter the passphrase for their secret key! That's the way CURVE25519 works: you encrypt a message using your secret key and the recipients public key and the recipient does the opposite, he uses his secret key and your public key to actually decrypt the message.

Oh - and if you're wondering why I named them Alicia and Bobby: I was just sick of Alice and Bob. We're running NSA-free, so we're using other sample names as well.

ASCII Cast Demo

There is an aciicast demonstrating the use of pcp.


There are currently no packages available, so pcp has to be compiled from source. Follow these steps:

First, you will need libsodium:

git clone git:// cd libsodium ./ ./configure && make check sudo make install sudo ldconfig cd ..

Next, pcp. You can fetch the latest GIT repository, but be aware, that it is a living source, there might be current changes underway, it might not be working:

git clone git:// cd pcp ./configure sudo make install cd ..

I'd rather suggest to download the current release file:


Unpack the tarball and compile with:

./configure make sudo make install

Optionally, you might run the unit tests:

make test

Please note that you'll need some perl modules installed in order to execute the unit tests: Config::General, Test::More and Tie::IxHash.

You may of course use PGP to verify the PGP signature of the tarball: pcp-0.3.0.tar.gz.gpg

File checksums are:

MD5 58a2e29a8a44ef75d0a64d2a74dd1172 SHA256 5a74b54b2426970e0d8a7c4b9fe8fdbe73af72a964a792cf34fa4e05846c82ce

You may want to look a the Changelog


To learn how to use pcp, read the manpage:

man pcp1

There's a HTML Version for online reading as well.

API Documentation

Documentation for the libpcp API can be read here.


Copyright (c) 2013-2015 by T.v.Dein

Additional Copyrights

Every incorporated source code is opensource and licensed under the GPL as well.




Licensed under the GNU GENERAL PUBLIC LICENSE version 3.