Tome

Tome is a lightweight password manager with a humane command-line interface.

Tome stores your passwords in an encrypted file which you manage with a single master password. You can keep track of multiple complex passwords without having to remember any of them.

Disclaimer I am not a security expert. I've only had limited formal training in security and cryptography. Now that I've scared off all but the bravest, feel free to look under the hood or at the security bits in crypt.rb.

Installation

• Install Ruby 1.9.3 or newer.
• gem install tome
• tome should now be available on the command-line. Run tome help to get started.

Usage

The first time you run tome, you'll be asked to create a master password for your encrypted password database. Any operations involving your password database will require this master password.

Creating a new password is simple:

> tome set linkedin.com
Creating tome database.
Master password:
Master password (verify):
Password:
Password (verify):
Created password for linkedin.com.

Recalling a password is just as easy:

> tome get linkedin.com
Master password:
Password for linkedin.com:
p4ssw0rd

In fact, it's even simpler than that. tome get does substring pattern matching to recall a password, so this works, too:

> tome get linked
Master password:
Password for linkedin.com:
p4ssw0rd

You can also generate and copy complex passwords without having to remember anything:

> tome generate last.fm
Master password:
Generated and copied password for last.fm.

> tome get last
Master password:
Password for last.fm:
kizWy76F2@G(21c11(9Tf?f@43B!kq

> tome copy last
Master password:
Password for last.fm copied to clipboard.

If you want, you can specify a username with your domain:

> tome set foo@bar.com baz
Master password:
Created password for foo@bar.com.

> tome get bar
Master password:
Password for foo@bar.com:
baz

See tome help for advanced commands and usage.

Philosophy

Tome is meant to be simple and secure. Instead of having blind trust in the secure coding practices of every website you sign up with, you can use tome to help mitigate your risk and exposure.

Benefits

• Easily maintain unique per-site passwords.
• Have complex passwords without having to remember them (see tome generate).
• If a website leaks your password or its hash, you can quickly generate another unique complex password.
• You can keep track of all of the various websites you have accounts with.

Drawbacks

• Single point of failure: if your .tome file is compromised, all of your passwords are potentially at risk. The encryption on the .tome file is meant to mitigate this danger. Brute-force decryption should take significant computing power and time. To further reduce risk, don't store usernames (e.g. do tome set gmail.com instead of tome set foo@gmail.com).
• Dependence on the .tome file: if your .tome file is lost or corrupt and you forget your passwords, you'll have to reset them.
• If you want access to your passwords on multiple machines, you'll have to sync the .tome file between machines.
• Trust in my secure coding practices. I encourage you to look at the source yourself.

Under the hood

All account and password information is stored in a single .tome file in the user's home directory. This file is YAML-formatted and stores the encrypted account and password information as well as the encryption parameters. These encryption parameters, along with the master password, are used to decrypt the password information.

A randomly-generated 1K-4K block of data is appended to the actual password data to obfuscate the number of passwords stored in the database. This is not a security mechanism, but rather a hindrance to attempts to infer anything from the encrypted data.

Each time the .tome file is modified, new encryption parameters (i.e. the salt and IV) are randomly generated and used for encryption.

Password database encryption

• Encryption algorithm: symmetric AES-256 CBC using the Ruby OpenSSL library.
• Key derivation:
  • PBKDF2/HMAC-SHA-512 with a master password.
  • UUID-based random, probabilistically unique salt from SecureRandom#uuid.
  • Randomly-generated IV from OpenSSL::Cipher#random_iv.
  • 100,000 key stretch iterations.

License

Copyright © 2013-2014 Chris Schmich
MIT License, see LICENSE for details.