libpam-bitid

A PAM module to use a bitcoin address for credentials.

This module is an implementation of the BitID protocol.

Currently only console and telnet login are supported.

Download

Current release:

• libpam-bitid_0.1.0_amd64.deb
• libpam-bitid-0.1.0.tar.bz2

Releases are archived in the git repository:

• Source tar-balls
• Ubuntu/debian packages
• Note: select the file and then select "RAW" button to start download.

Requires

• autoconfig
• libtool

Build

1. git clone https://github.com/angrycod/libpam-bitid.git
2. cd libpam_bitid
3. ./autogen.sh
4. ./configure --prefix=/usr
5. make

Install

1. sudo make install
2. sudo cp examples/bitid.access /etc/bitid.access
3. sudo vi /etc/pam.d/login Edit to add the lines from examples/login.diff

Ubuntu/debian install

1. sudo dpkg -i libpam-bitid_0.1.0_amd64.deb

Configuration

vi /etc/bitid.access Edit to include your list of allowed address/username pairs

# bitid.access:
# List of users allowed access using login by bitcoin address
#
# format:
# bitcoin-address, username
1DvRd44mD8EuCcym8zymYzabvmozwZ5r8G, btctest

vi /etc/pam.d/login Edit to allow bitid login using telnet:

Add this line at the very top: auth optional pam_bitid.so file=/etc/bitid.access

And comment out this line: # @include common-auth

If common-auth is still enabled then pam will try and do a unix login after doing the bitid login.

Logs

Check /var/log/auth.log on Ubuntu for output of libpam-bitid module.

Upon successful bitid authentication you will see messages from pam_bitid.

pam_bitid(login:auth): user: btctest allowed access from: 1DvRd44mD8EuCcym8zymYzabvmozwZ5r8G

Testing example configuration

It's clunky, but for testing this select the address in electrum and sign the challenge message provided by the pam-bitid login with that.

To get a login prompt, telnet 127.0.0.1 and then enter your bitcoin address.

$ telnet localhost
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Ubuntu 14.04.1 LTS
bitcoin address: 1DvRd44mD8EuCcym8zymYzabvmozwZ5r8G
challenge message: dbcbd542b29a3c4298651035ae6eaed3
signature: HE8DDp4eAEy61417XTPAQTOqPBcLP2h0Y0sTB9hfFILCv8ZpLzdH6dh/z6+o7A4VwwjM1Qq2SFVcgyf7U51JhdE=
Last login: Wed May 21 18:42:01 PDT 2014 from localhost on pts/17
Welcome to Ubuntu 13.10 (GNU/Linux 3.11.0-12-generic x86_64)
 
btctest:~$

Notes:

• Signatures are in electrum format, so signature will not be valid if using another format. Many clients use the electrum format, so clients other than electrum may work okay.

References

• [BitID protocol specification] (https://github.com/bitid/bitid)
• [Linux-PAM] (http://www.linux-pam.org)
• [Bitcoin protocol specification] (https://en.bitcoin.it/wiki/Protocol_specification)

Credits

Jay Schulist jayschulist@gmail.com