blst

The blst crate provides a rust interface to the blst BLS12-381 signature library.

Build

bindgen is used to generate FFI bindings to blst.h. Then build.rs invokes C compiler to compile everything into libblst.a within the rust target build area. On Linux it's possible to choose compiler by setting CC environment variable.

Everything can be built and run with the typical cargo commands:

cargo test
cargo bench

If the test or target application crashes with an "illegal instruction" exception [after copying to an older system], set CFLAGS environment variable to ‑D__BLST_PORTABLE__ prior clean build. Alternatively, if you compile on an older Intel system, but will execute the binary on a newer one, consider instead ‑D__ADX__ for better performance.

Usage

There are two primary modes of operation that can be chosen based on declaration path:

For minimal-pubkey-size operations:

use blst::min_pk::*

For minimal-signature-size operations:

use blst::min_sig::*

There are five structs with inherent implementations that provide the BLS12-381 signature functionality.

SecretKey
PublicKey
AggregatePublicKey
Signature
AggregateSignature

A simple example for generating a key, signing a message, and verifying the message:

let mut ikm = [0u8; 32];
rng.fill_bytes(&mut ikm);

let sk = SecretKey::key_gen(&ikm, &[]).unwrap();
let pk = sk.sk_to_pk();

let dst = b"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_NUL_";
let msg = b"blst is such a blast";
let sig = sk.sign(msg, dst, &[]);

let err = sig.verify(msg, dst, &[], &pk);
assert_eq!(err, BLST_ERROR::BLST_SUCCESS);

See the tests in src/lib.rs and benchmarks in benches/blst_benches.rs for further examples of usage.