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 those methods. All Django's built-in hashers 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.

TL;DR

Content of examples/tldr.rs:

extern crate djangohashers;
use djangohashers::*;

fn main() {
    let encoded = make_password("K2jitmJ3CBfo");
    println!("Hash: {:?}", encoded);
    let is_valid = check_password("K2jitmJ3CBfo", &encoded).unwrap();
    println!("Is valid: {:?}", is_valid);
}

Output:

$ cargo run --quiet --example tldr
Hash: "pbkdf2_sha256$390000$7HRd1YJBZvYj$Rc3BW6f7ss3CShWkULiXI9Rxj7CDdstBeoyCgFFQaK0="
Is valid: true

Installation

Add the dependency to your Cargo.toml:

[dependencies]
djangohashers = "^1.7"

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};

Compiling Features

By default all the hashers are enabled, but you can pick only the hashers that you need to avoid unneeded dependencies.

• default: all hashers.
• with_pbkdf2: only PBKDF2 and PBKDF2SHA1.
• with_argon2: only Argon2.
• with_scrypt: only Scrypt.
• with_bcrypt: only BCrypt and BCryptSHA256.
• with_legacy: only SHA1, MD5, UnsaltedSHA1, UnsaltedMD5 and Crypt.
• fpbkdf2: enables Fast PBKDF2 (requires OpenSSL, see below).
• fuzzy_tests: only for development, enables fuzzy tests.

Fast PBKDF2 Version

Depending on your platform, OS and version of libraries, it is possible that DjangoHashers can be slower than Python/Django's reference implementation. If performance is critical for your case, there is an alternatice implementation: the package fastpbkdf2 uses a C-binding of a library that requires OpenSSL. If ring's implementation of PBKDF2 reaches this level of optiomization, the fastpbkdf2 version will be deprecated.

Installation

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

[dependencies.djangohashers]
version = "^1.7"
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 macOS you may need to do something like this:

$ brew install openssl
$ export LIBRARY_PATH="$(brew --prefix openssl)/lib"
$ export CFLAGS="-I$(brew --prefix openssl)/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

On a Quad-Core Intel Core i7:

On a Apple M1:

Replicate test above with Docker:

$ docker build -t rs-dj-hashers-profile .
...

$ docker run -t rs-dj-hashers-profile
Hashing time: 65ms (Python 3.11.1, Django 4.1.5).
Hashing time: 38ms (Vanilla PBKDF2).
Hashing time: 26ms (Fast PBKDF2).

Compatibility

DjangoHashers passes all relevant unit tests from Django 1.4 to 5.1 (and beta of 5.2), there is even a line-by-line translation of tests/auth_tests/test_hashers.py.

What is not covered:

• 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 docs.rs 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::BadHash: Hash string is corrupted.
• HasherError::InvalidIterations: number of iterations is not a positive integer.
• HasherError::EmptyHash: hash string is empty.
• HasherError::InvalidArgon2Salt: Argon2 salt should be Base64 encoded.

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::Argon2
• Algorithm::Scrypt
• Algorithm::BCryptSHA256
• Algorithm::BCrypt
• Algorithm::SHA1
• Algorithm::MD5
• Algorithm::UnsaltedSHA1
• Algorithm::UnsaltedMD5
• Algorithm::Crypt

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=

Warning: make_password_with_settings and make_password_core will both panic if salt is not only letters and numbers (^[A-Za-z0-9]*$).

Generating a Hashed Password based on a Django version

Django versions can have different number of iterations for hashers based on PBKDF2 and BCrypt algorithms; this abstraction makes possible to generate a password with the same number of iterations used in that versions.

use djangohashers::{Django, DjangoVersion};

let django = Django {version: DjangoVersion::V1_8};  // Django 1.8.
let encoded = django.make_password("KRONOS");
// Returns something like:
// pbkdf2_sha256$20000$u0C1E8jrnAYx$7KIo/fAuBJpswQyL7pTxO06ccrSjGdIe7iSqzdVub1w=
//               |||||
// ...notice the 20000 iterations, used in Django 1.8.

Available versions:

• DjangoVersion::CURRENT Current Django version (5.1 for DjangoHashers 1.7.4).
• DjangoVersion::V1_4 Django 1.4
• DjangoVersion::V1_5 Django 1.5
• DjangoVersion::V1_6 Django 1.6
• DjangoVersion::V1_7 Django 1.7
• DjangoVersion::V1_8 Django 1.8
• DjangoVersion::V1_9 Django 1.9
• DjangoVersion::V1_10 Django 1.10
• DjangoVersion::V1_11 Django 1.11
• DjangoVersion::V2_0 Django 2.0
• DjangoVersion::V2_1 Django 2.1
• DjangoVersion::V2_2 Django 2.2
• DjangoVersion::V3_0 Django 3.0
• DjangoVersion::V3_1 Django 3.1
• DjangoVersion::V3_2 Django 3.2
• DjangoVersion::V4_0 Django 4.0
• DjangoVersion::V4_1 Django 4.1
• DjangoVersion::V4_2 Django 4.2
• DjangoVersion::V5_0 Django 5.0
• DjangoVersion::V5_1 Django 5.1
• DjangoVersion::V5_2 Django 5.2

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".