blstrs_plus

This crate provides an implementation of the BLS12-381 pairing-friendly elliptic curve construction with hash-to-curve and multi-exponentiation methods.

• This implementation has not been reviewed or audited. Use at your own risk.
• This implementation targets Rust 1.87 or later.
• This implementation does not require the Rust standard library.
• All operations are constant time unless explicitly noted.

Features

• bits (on by default): Enables APIs for obtaining bit iterators for scalars.
• groups (on by default): Enables APIs for performing group arithmetic with G1, G2, and GT.
• pairings (on by default): Enables APIs for performing pairings.
• alloc (on by default): Enables APIs that require an allocator.
• ark: Enables compatibility with the arkworks ecosystem and the Rust standard library.
• expose-fields: Exposes the internal field modules; this also enables groups.
• std: Enables APIs that require the Rust standard library.

Trait compatibility

• elliptic-curve, ff, and group 0.14 traits are implemented for Scalar, the G1/G2 types, and the Bls12381G1/Bls12381G2 curve markers.
• The ff and group 0.13 traits are also implemented, because pairing 0.23 needs them. They are re-exported as ff_013 and group_013.
• elliptic-curve 0.13 is no longer supported as of 0.10.0.

Hashing to curve

Hash-to-curve follows RFC 9380 and takes any hash2curve 0.14 ExpandMsg at the 128-bit security level:

use blstrs_plus::{G1Projective, G2Projective, Scalar};
use hash2curve::ExpandMsgXmd;
use sha2::Sha256;

let msg = b"message";
let p = G1Projective::hash::<ExpandMsgXmd<Sha256>>(msg, b"BLS_SIG_BLS12381G1_XMD:SHA-256_SSWU_RO_NUL_");
let q = G2Projective::hash::<ExpandMsgXmd<Sha256>>(msg, b"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_NUL_");
let s = Scalar::hash::<ExpandMsgXmd<Sha256>>(msg, b"my-scalar-dst");

This needs hash2curve = "0.14" and sha2 = "0.11" in your Cargo.toml. The DST must be non-empty, or these functions panic.

Testing

Test for non-wasm32 targets:

cargo test --all-features

Test wasm32 targets:

cargo test --target wasm32-unknown-unknown

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.