Pixel signature scheme

This is Algorand's implementation of Pixel signature, over the BLS12-381 curve. Useful links:

• Paper
• Spec
• Rust code: this repo
• Python code
• Another python code <- This code is only for generating test vectors and cross comparing with Rust's output. It should not be used for any other purpose.

Dependencies

• Pairing-plus library: Github, Crate.io
  • A fork of zkcrypto's pairing library; with additional functions such as hash to groups and membership testing, etc.
  • We rely heavily on this library for underlying arithmetics.
• Pixel_param: Github
  • We use the default parameters generated from this crate.
• BLS_SIG: Github, Crate.io
  • This library is only used for generating and verifying proof of possession.

Code status

• Version Alpha.
• This code has NOT been deployed in production.
• This code has been externally audited by two consulting firms.

Build options

• cargo build builds a debug version;
• cargo build --release builds the release version;

Test options

• cargo test [--release] runs basic tests;
• cargo test -- --ignored [--release] runs long tests;
• cargo bench runs benchmarks.

Cross comparison with python code

• test_vector calls this rust library to generate a list of test vectors.
• pixel-python/test_vector.py is a python script that generates a list of test vectors.
• test_vector.py also compares the binary outputs of Rust and python match.

Quality control

Following the guidelines from Facebook's libra source code and Rust API Guidelines.

• cargo fmt for coding style
• cargo clippy --all-targets --all-features -- -D warnings for lint
• cargo doc for documentation.

Exceptions:

• Facebooks guidelines suggests to have a test file along with the source code. Pixel has a separate test folder that contains all test codes.

Crypto Hygiene

• Variables that storing secret data are named with a suffix _sec. Always ensure primitive types get cleaned with Zeroize crate; or get passed to the caller. Secret key related structures implements zeroing on drop.
• Avoiding using clone() function on secret data as possible - this will create two copies of the data. If clone() is used, always clean it after use.

Interfaces documentation

• Run cargo doc --open
• See target/doc/pixel/index.html

Wrapper

• Generated with cbindgen
• See c_wrapper