TBD

Library providing privacy enhancing cryptographic primitives.

Primitives

1. Schnorr proof of knowledge protocol to prove knowledge of discrete log and inequality of discrete logs. This is a good reference.
2. BBS and BBS+ signatures for anonymous credentials. BBS+ is based on the paper Anonymous Attestation Using the Strong Diffie Hellman Assumption Revisited and BBS is based on the paper Revisiting BBS Signatures. Also implements the threshold variants of these based on the paper Threshold BBS+ Signatures for Distributed Anonymous Credential Issuance
3. Dynamic accumulators, both positive and universal. Based on the papers Dynamic Universal Accumulator with Batch Update over Bilinear Groups and Efficient Constructions of Pairing Based Accumulators. Implements a keyed-verification variant of these accumulators as well which does not require pairings.
4. Composite proof system that combines above primitives for use cases like
   • prove knowledge of a BBS+ signature and the corresponding messages
   • prove knowledge of a modified PS signature and the corresponding messages
   • equality of signed messages (from same or different signatures) in zero knowledge
   • inequality of signed messages with public or committed values in zero knowledge
   • the (non)membership of a certain signed message(s)in the accumulator
   • numeric bounds (min, max) on the messages can be proved in zero-knowledge
   • verifiable encryption of signed messages under BBS+ or PS.
   • zk-SNARK created from R1CS and WASM generated by Circom with witnesses as BBS+ signed messages (not exclusively though).
5. Verifiable encryption using SAVER.
6. Compression and amortization of Sigma protocols. This is PoC implementation.
7. Secret sharing schemes and DKG. Implements several verifiable secret sharing schemes and DKG from Gennaro and FROST. Also implements protocol to do a distributed DLOG check.
8. Cocount and PS signatures. Based on the paper Security Analysis of Coconut, an Attribute-Based Credential Scheme with Threshold Issuance
9. LegoGroth16. LegoGroth16, the LegoSNARK variant of Groth16 zkSNARK proof system
10. Oblivious Transfer (OT) and Oblivious Transfer Extensions (OTE).
11. Short group signatures. BB signature and weak-BB signature and their proofs of knowledge based on the papers Short Signatures Without Random Oracles and Scalable Revocation Scheme for Anonymous Credentials Based on n-times Unlinkable Proofs.
12. Keyed-Verification Anonymous Credentials (KVAC). Implements Keyed-Verification Anonymous Credentials (KVAC) schemes.
13. SyRA. Implements sybil resilient signatures to be used for generating pseudonyms for low-entropy credential attributes.
14. Verifiable encryption using the paper Verifiable Encryption from MPC-in-the-Head.

Composite proof system

The proof system that uses above-mentioned primitives.

Build

cargo build or cargo build --release

By default, it uses standard library and rayon for parallelization

To build with standard library but without parallelization, use cargo build --no-default-features --features=std

For no_std support, build as cargo build --no-default-features --features=wasmer-sys

For WASM, build as cargo build --no-default-features --features=wasmer-js --target wasm32-unknown-unknown

Test

cargo test

The above maybe slower as it runs the tests in debug mode and some tests work on large inputs. For running tests faster, run cargo test --release

Some tess might cause a stack overflow error. To fix that, increase the stack size to about 8MB as

RUST_MIN_STACK=8388608 cargo test or RUST_MIN_STACK=8388608 cargo test --release

Benchmarking

Criterion benchmarks here

Some tests also print time consumed by the operations, run cargo test --release -- --nocapture [test name]

WASM wrapper

A WASM wrapper has been created over this repo here. The wrapper is then used to create this Typescript library which is more ergonomic than using the wrapper as the wrapper contains free floating functions.