This repository is the home to a performant multi-message digital signature algorithm implementation which supports deriving zero knowledge proofs that enable selective disclosure from the originally signed message set.
BBS+ Signatures are a digital signature algorithm originally born from the work on Short group signatures by Boneh, Boyen, and Shachum which was later improved on in Constant-Size Dynamic k-TAA as BBS+ and touched on again in section 4.3 in Anonymous Attestation Using the Strong Diffie Hellman Assumption Revisited .
BBS+ signatures require a pairing-friendly curve, this library includes support for BLS12-381.
BBS+ Signatures allow for multi-message signing whilst producing a single output signature. With a BBS signature, a proof of knowledge based proof can be produced where only some of the originally signed messages are revealed at the discretion of the prover.
For more details on the signature algorithm please refer to here.
To use this package within your project simply run
npm install @mattrglobal/bbs-signatures
Or with Yarn
yarn add @mattrglobal/bbs-signatures
This library includes a couple of features to ensure the most performant implementation of BBS is running in a execution environment. The order of selection is the following.
- If in a node js based environment and the optional dependency of @mattrglobal/node-bbs-signatures is installed use this.
- If in an environment that supports Web Assembly use this.
Note Please refer to running the benchmarks below where you can compare these different implementations, the differences are very notable.
Note To force the usage of a particular environment set the BBS_SIGNATURES_MODE environment variable to one of the following values
NODE_JS_MODULE- Use native node module, ensure @mattrglobal/node-bbs-signatures is installedWASM- Use the wasm module
Note Previous releases of this library supported an asm.js compilation for usage in react native environments, however this has been deprecated due to performance issues.
See the sample directory for a runnable demo's.
The following is a short sample on how to use the API
import {
generateBls12381G2KeyPair,
blsSign,
blsVerify,
blsCreateProof,
blsVerifyProof,
} from "@mattrglobal/bbs-signatures";
//Generate a new key pair
const keyPair = await generateBls12381G2KeyPair();
//Set of messages we wish to sign
const messages = [
Uint8Array.from(Buffer.from("message1", "utf-8")),
Uint8Array.from(Buffer.from("message2", "utf-8")),
];
//Create the signature
const signature = await blsSign({
keyPair,
messages: messages,
});
//Verify the signature
const isVerified = await blsVerify({
publicKey: keyPair.publicKey,
messages: messages,
signature,
});
//Derive a proof from the signature revealing the first message
const proof = await blsCreateProof({
signature,
publicKey: keyPair.publicKey,
messages,
nonce: Uint8Array.from(Buffer.from("nonce", "utf8")),
revealed: [0],
});
//Verify the created proof
const isProofVerified = await blsVerifyProof({
proof,
publicKey: keyPair.publicKey,
messages: messages.slice(0, 1),
nonce: Uint8Array.from(Buffer.from("nonce", "utf8")),
});Within a digital signature there are several elements for which it is useful to know the size, the following table outlines the general equation for calculating element sizes in relation to BBS+ signatures as it is dependent on the pairing friendly curve used.
| Element | Size Equation |
|---|---|
| Private Key | F |
| Public Key | G2 |
| Signature | G1 + 2*F |
| Proof | 5*G1 + (4 + no_of_hidden_messages)*F |
FA field elementG1A point in the field of G1G2A point in the field of G2no_of_hidden_messagesThe number of the hidden messages
This library includes specific support for BLS12-381 keys with BBS+ signatures and hence gives rise to the following concrete sizes
| Element | Size with BLS12-381 |
|---|---|
| Private Key | 32 Bytes |
| Public Key | 96 Bytes |
| Signature | 112 Bytes |
| Proof | 368 + (no_of_hidden_messages)*32 Bytes |
The following describes how to get started as a contributor to this project
The following is a list of dependencies you must install to build and contribute to this project
For more details see our contribution guidelines
To install the package dependencies run:
yarn install --frozen-lockfile
To build the project for debug run:
yarn build
To run the all test in the project run:
yarn test
To run just the tests for a node environment using the native node module of @mattrglobal-node-bbs-signatures run:
yarn test:node
To run just the tests for a node environment using the wasm module run:
yarn test:wasm
To run just the tests for a browser environment run:
yarn test:browser
To benchmark the implementation locally in a node environment using the native node module of @mattrglobal-node-bbs-signatures run:
yarn benchmark:node
To benchmark the implementation locally in a node environment using the wasm module run:
yarn benchmark:wasm
This library uses the bbs rust crate for the implementation of BBS+ signatures and BLS12-381 which is then wrapped and exposed in javascript/typescript using Web Assembly.
Please see our security policy for additional details about responsible disclosure of security related issues.
For those interested in more details, you might find the following resources helpful
- Details on the algorithm
- BLS12-381 For The Rest Of Us
- Pairing-based cryptography
- Exploring Elliptic Curve Pairings
- Anonymous Attestation Using the Strong Diffie Hellman Assumption Revisited
- Pairing Friendly Curves
- BLS Signatures
Copyright © MATTR Limited. Some rights reserved.
“MATTR” is a trademark of MATTR Limited, registered in New Zealand and other countries.
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