Rust DjangoHashers

A Rust port of the password primitives used in Django Project.

Django's django.contrib.auth.models.User class has a few methods to deal with passwords, like set_password() and check_password(); DjangoHashers implements the primitive functions behind that methods. All Django's built-in hashers (except UNIX's crypt(3)) are supported.

This library was conceived for Django integration, but is not limited to it; you can use the password hash algorithm in any Rust project (or FFI integration), since its security model is already battle-tested.

Instalation

Add the dependency to your Cargo.toml:

[dependencies]
djangohashers = "0.2.0"

Reference and import:

extern crate djangohashers;

// Everything (it's not much):
use djangohashers::*;

// Or, just what you need:
use djangohashers::{check_password, make_password, Algorithm};

Fast PBKDF2 Version

Unfortunately rust-crypto’s implementation of PBKDF2 is not properly optimized: it does not adheres to the loop inlines and buffering used in modern implementations. The package fastpbkdf2 uses a C-binding of a library that requires OpenSSL.

Instalation

Add the dependency to your Cargo.toml declaring the feature:

[dependencies.djangohashers]
version = "0.2.0"
features = ["fpbkdf2"]

You need to install OpenSSL and set the environment variable to make it visible to the compiler; this changes depending on the operation system and package manager, for example, in OS X with MacPorts you may need to do something like this:

$ sudo port install openssl
$ CFLAGS="-I/opt/local/include" cargo ...

For other OSs and package managers, follow the guide of how to install Python’s Cryptography dependencies, that also links against OpenSSL.

Performance

Notes:

• Best of 5 rounds of 100 events.
• Built with --release.
• PBKDF2 using SHA256 and iteration count set to 24000.
• Django version tested with CPython 3.5.1
• Rust/fastpbkdf2 version tested with Rust 1.6.0 and OpenSSL 1.0.2g.
• iMac Mid 2010 with an Intel Core i3 3.2Ghz and 16GB of RAM, running OS X 10.11.3.

Compatibility

DjangoHashers passes all relevant unit tests from Django 1.9, there is even a line-by-line translation of tests/auth_tests/test_hashers.py.

What is not covered:

• CryptPasswordHasher, that uses UNIX's crypt(3) hash function.
• Upgrade/Downgrade callbacks.
• Any 3rd-party hasher outside Django's code.
• Some tests that makes no sense in idiomatic Rust.

Usage

API Documentation, thanks to crates.fyi project!

Verifying a Hashed Password

Function signatures:

pub fn check_password(password: &str, encoded: &str) -> Result<bool, HasherError> {}
pub fn check_password_tolerant(password: &str, encoded: &str) -> bool {}

Complete version:

let password = "KRONOS"; // Sent by the user.
let encoded = "pbkdf2_sha256$24000$..."; // Fetched from DB.

match check_password(password, encoded) {
    Ok(valid) => {
        if valid {
            // Log the user in.
        } else {
            // Ask the user to try again.
        }
    }
    Err(error) => {
        // Deal with the error.
    }
}

Possible Errors:

• HasherError::UnknownAlgorithm: anything not recognizable as an algorithm.
• HasherError::InvalidIterations: number of iterations is not a positive integer.
• HasherError::EmptyHash: hash string is empty.

If you want to automatically assume all errors as "invalid password", there is a shortcut for that:

if check_password_tolerant(password, encoded) {
	// Log the user in.
} else {
	// Ask the user to try again.
}

Generating a Hashed Password

Function signatures:

pub fn make_password(password: &str) -> String {}
pub fn make_password_with_algorithm(password: &str, algorithm: Algorithm) -> String {}
pub fn make_password_with_settings(password: &str, salt: &str, algorithm: Algorithm) -> String {}

Available algorithms:

• Algorithm::PBKDF2 (default)
• Algorithm::PBKDF2SHA1
• Algorithm::BCryptSHA256
• Algorithm::BCrypt
• Algorithm::SHA1
• Algorithm::MD5
• Algorithm::UnsaltedSHA1
• Algorithm::UnsaltedMD5

The algorithms follow the same Django naming model, minus the PasswordHasher suffix.

Using default settings (PBKDF2 algorithm, random salt):

let encoded = make_password("KRONOS");
// Returns something like:
// pbkdf2_sha256$24000$go9s3b1y1BTe$Pksk4EptJ84KDnI7ciocmhzFAb5lFoFwd6qlPOwwW4Q=

Using a defined algorithm (random salt):

let encoded = make_password_with_algorithm("KRONOS", Algorithm::BCryptSHA256);
// Returns something like:
// bcrypt_sha256$$2b$12$e5C3zfswn.CowOBbbb7ngeYbxKzJePCDHwo8AMr/SZeZCoGrk7oue

Using a defined algorithm and salt (not recommended, use it only for debug):

let encoded = make_password_with_settings("KRONOS", "seasalt", Algorithm::PBKDF2SHA1);
// Returns exactly this (remember, the salt is fixed!):
// pbkdf2_sha1$24000$seasalt$F+kiWNHXbMBcwgxsvSKFCWHnZZ0=

Verifying a Hash Format (pre-crypto)

Function signature:

pub fn is_password_usable(encoded: &str) -> bool {}

You can check if the password hash is properly formatted before running the expensive cryto stuff:

let encoded = "pbkdf2_sha256$24000$..."; // Fetched from DB.

if is_password_usable(encoded) {
    // Go ahead.
} else {
    // Check your database or report an issue.
}

Contributing

• Be patient with me, I’m new to Rust and this is my first project.
• Don't go nuts with your mad-rust-skillz, legibility is a priority.
• Please use rustfmt in your code.
• Always include some test case.

License

Rust DjangoHashers is released under the 3-Clause BSD License.

tl;dr: "free to use as long as you credit me".