pbp 0.2.1

pbp

v0.2 - experimental

PBP[0] is a simple python wrapper and a command line interface around libsodium, to provide basic functionality resembling PGP. It uses scrypt for a KDF and a much simpler packet format, which should be much harder to fingerprint, pbp also provides an experimental forward secrecy mode and a multi-party DH mode.

Installation

You possibly need to run (or an equivalent command) sudo apt-get install git python-virtualenv gcc python-dev libffi-dev to satisfy all basic dependencies.

pip install pbp

optionally for PITCHFORK support also

pip install pyusb==1.0.0b1

Design goals:

1. use modern crypto

2. provide similar functionality to PGP

3. be extensible

4. difficult to identify based on fingerprinting

5. provide extensive testing

6. strive for security

Crypto

Cryptographic primitives are based on the NaCl library from http://nacl.cr.yp.to. The KDF used is scrypt.

PGP-like

Provides basic public key encrypt/decrypt, sign/verify and secret key encrypt/decrypt modes, as well as the ability to sign, verify, list, generate, export and import keys.

Extensibility

using pbp and the underlying pysodium[1] library it’s easy to extend pbp. Some examples are the experimental forward secrecy mode (see description in docs/chaining-dh.txt), the support for ECDH key exchanges from the command-line and generation of arbitrarily large random byte streams.

[1] https://github.com/stef/pysodium also available on

https://pypi.python.org/pypi/pysodium

Fingerprinting

pbp tries to avoid to store any sensitive plaintext info, the encrypted files all should look like random noise. for a description of the packet formats see docs/fileformats.txt.

Testing

All py files come with their internal tests, unit tests are in tests.py, and commandline functionality is tested in test.sh.

Security

pbp locks the process memory, so it cannot be swapped to disk. Also pbp uses SecureString[2] to overwrite sensitive key material after usage in memory, so keys have a short window of opportunity to leak.

[2] https://github.com/dnet/pysecstr

Usage

Generate a key

pbp -g -n alice

sending howdy.txt using public key encryption from alice to bob

pbp -c -S alice -r bob -i howdy.txt

decrypt an encrypted file using public key crypto

pbp -d -S bob -i howdy.txt.pbp

sending howdy.txt using secret key encryption

pbp -c -i howdy.txt

decrypt an encrypted file using secret key crypto

pbp -d -i howdy.txt.pbp

sign howdy.txt

pbp -s -S alice -i /howdy.txt

verify howdy.txt

pbp -v -i howdy.txt.sig

sign bobs key

pbp -m -S alice -n bob

check sigs on carols key

pbp -C -n carol

alice encrypts howdy.txt to bob using experimental forward secret mode

pbp -e -S alice -r bob -i howdy.txt -o ./secret-message

bob decrypts howdy.txt from alice using experimental forward secret mode

pbp -E -S bob -r alice -i ./secret-message

initiate ECDH key exchange

pbp -D1

respond to ECDH key exchange

pbp -D2 -Dp ‘public component from D1’

finish ECDH key exchange

pbp -D3 -Dp ‘public component from D2’ -De ‘secret exponent from D1’

random streaming 23GByte of cryptographic randomness

pbp -R -Rs 23G -o /mnt/huge_fs/random_data

participate in a 4-way DH exchange, 1st message

pbp -Ds -Dp 4 -S alice -n ‘friends001’ -i oldkeychain -o newkeychain

participate in a 4-way DH exchange, 2nd message

pbp -De -S alice -n ‘friends001’ -i oldkeychain -o newkeychain

this is one big pipe that creates a 3-way ECDH secret between alice, bob and carol:

pbp -Ds -S alice -Dp 3 -n ‘test-dh’ -i /dev/null |

pbp -Ds -S bob -Dp 3 -n ‘test-dh’ | pbp -Ds -S carol -Dp 3 -n ‘test-dh’ | pbp -De -S alice -Dp 3 -n ‘test-dh’ | pbp -De -S bob -Dp 3 -n ‘test-dh’

of course instead of a pipe you could use any kind of transport mechanism

Integration

you can add the following to your .vimrc

map ;e :%!/bin/sh -c ‘pbp -c 2>/dev/tty | base64’<C-M> map ;d :%!/bin/sh -c ‘base64 -d | pbp -d 2>/dev/tty’<C-M> map ;s :,$! /bin/sh -c ‘pbp -s -a -S stf 2>/dev/tty’<C-M> map ;v :,$! /bin/sh -c ‘pbp -v -a 2>/dev/tty’<C-M>

3. 2013, stf <s@ctrlc.hu>, dnet vsza@vsza.hu, AGPLv3.0+

[0] also it’s very funny to say pbp with a mouth full of dry cookies. don’t try this in company!