@kaytrust/prooftypes

@kaytrust/prooftypes is a library that allows the creation and verification of W3C Verifiable Credentials and Presentations in JWT format, using the JwtProof2020 proof type.

Features

• Creation of Verifiable Credentials (VC) in JWT format.
• Creation of Verifiable Presentations (VP) in JWT format.
• Verification of VC and VP using DID-compatible resolvers.
• Support for multiple DID methods, such as did:near and did:ethr.

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Installation

You can install the library using npm or yarn:

npm install @kaytrust/prooftypes
# or
yarn add @kaytrust/prooftypes

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Usage

Introduction

The library provides the ProofTypeJWT class to handle the creation and verification of proofs in JWT format. Below are the steps required to use it.

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Initial Configuration

ProofTypeJWT Constructor

constructor(options: ProofTypeJWTConfig={},is_presentation?: boolean)

• ProofTypeJWTConfig: Optional configuration for the issuer (Issuer) or verification options (resolver and verifyOptions).
• is_presentation: If true, it will work with Verifiable Presentations; otherwise, it will work with Verifiable Credentials.

ProofTypeJWTConfig Type

typeProofTypeJWTConfig={issuer?: Issuer,// Issuer to sign JWTsresolver?: ResolverOrOptions,// Resolver to verify JWTsverifyOptions?: VerifyOptions,// Additional verification options}

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Creating JWTs

Prerequisites

Before creating a JWT, you need to configure an Issuer object to sign the JWTs. You can use libraries such as @kaytrust/did-near or @kaytrust/did-ethr.

Example of Configuring an Issuer

import{NearDID}from'@kaytrust/did-near'import{EthrDID}from'@kaytrust/did-ethr'// NearDID Configurationconstissuer=newNearDID({privateKey: 'YOUR_PRIVATE_KEY',identifier: 'alice.near',// Optional})// EthrDID ConfigurationconstissuerEthr=newEthrDID({identifier: '0xf1232f840f3ad7d23fcdaa84d6c66dac24efb198',// RequiredprivateKey: 'YOUR_PRIVATE_KEY'})

The Issuer object includes:

• did: Identifier of the issuer.
• alg: Algorithm used in the JWT header.
• signer: Function to generate the signature.

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Creating a Verifiable Credential (VC)

1. Define the credential payload following the JwtCredentialPayload interface.
2. Use the generateProof method of the ProofTypeJWT class to generate the JWT.

Example

import{JwtCredentialPayload,ProofTypeJWT}from'@kaytrust/prooftypes'constvcPayload: JwtCredentialPayload={sub: 'did:near:...',nbf: 1562950282,vc: {'@context': ['https://www.w3.org/2018/credentials/v1'],type: ['VerifiableCredential'],credentialSubject: {degree: {type: 'BachelorDegree',name: 'Baccalauréat en musiques numériques'}}}}constproofTypeJwtCredential=newProofTypeJWT({ issuer })constvcJwt=awaitproofTypeJwtCredential.generateProof(vcPayload)console.log(vcJwt)// eyJ0eXAiOiJKV1QiLCJhbGciOiJFUzI1NkstUiJ9.eyJpYXQi...0CQmqB14NnN5XxD0d_glLRs1Myc_LBJjnuNwE

Creating a Verifiable Presentation (VP)

1. Define the presentation payload following the JwtPresentationPayload interface.
2. Use the generateProof method of the ProofTypeJWT class, setting the is_presentation parameter to true.

Example

import{JwtPresentationPayload,ProofTypeJWT}from'@kaytrust/prooftypes'constvpPayload: JwtPresentationPayload={vp: {'@context': ['https://www.w3.org/2018/credentials/v1'],type: ['VerifiablePresentation'],verifiableCredential: [vcJwt]}}constproofTypeJwtPresentation=newProofTypeJWT({ issuer },true)constvpJwt=awaitproofTypeJwtPresentation.generateProof(vpPayload)console.log(vpJwt)// eyJ0eXAiOiJKV1QiLCJhbGciOiJFUzI1NkstUiJ9.eyJpYXQiOjE1ODI1NDc...JNMUzZ6naacuWNGdZGuU0ZDwmgpUMUqIzMqFFRmge0R8QA

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Verifying JWTs

Prerequisites

To verify a JWT, you need a resolver that can resolve DID documents. You can use did-resolver with specific resolvers such as did:near or did:ethr.

Example of Configuring a Resolver

import{ResolverOrOptions}from'@kaytrust/prooftypes'import{Resolver}from'did-resolver'import{getResolverasgetNearResolver}from'@kaytrust/did-near-resolver'importethrfrom'ethr-did-resolver'constnearResolver=getNearResolver()constethrResolver=ethr.getResolver()//If you are using multiple methods you need to flatten them into one objectconstresolver:ResolverOrOptions=newResolver({
...nearResolver,
...ethrResolver,})//If you are using one method you can simply pass the result of getResolver( into the constructorconstresolver:ResolverOrOptions=newResolver(nearResolver);

EthrDID resolver options example

Setting resolver options for ethr-did-resolver

import{ResolverOrOptions,ProofTypeJWT}from'@kaytrust/prooftypes'constRPC_AMOY="<RPC_AMOY>";constAMOY_CHAIN_ID=80002;constresolver:ResolverOrOptions={registry: '0xBC56d0883ef228b2B16420E9002Ece0A46c893F8',rpcUrl: RPC_AMOY,chainId: AMOY_CHAIN_ID}

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Verifying a Verifiable Credential (VC)

Use the verifyProof method of the ProofTypeJWT class to verify the JWT.

Example

import{ProofTypeJWT}from'@kaytrust/prooftypes'constproofTypeJwtCredential=newProofTypeJWT({ resolver })constverifiedVC=awaitproofTypeJwtCredential.verifyProof(vcJwt)console.log(verifiedVC)

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Verifying a Verifiable Presentation (VP)

Use the verifyProof method of the ProofTypeJWT class, setting the is_presentation parameter to true.

Example

import{ProofTypeJWT}from'@kaytrust/prooftypes'constproofTypeJwtPresentation=newProofTypeJWT({ resolver },true)constverifiedVP=awaitproofTypeJwtPresentation.verifyProof(vpJwt)console.log(verifiedVP)

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Additional Notes

• The JwtProof2020 proof type is a synthetic type for internal use and is not registered in the W3C data model.
• Verified payloads are aligned with the W3C data model, making them easier to use in systems that handle multiple credential formats.

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Contributions

If you want to contribute to this project, please open an issue or submit a pull request.

🟣 ProofTypeNear

This proof type allows you to register and verify verifiable credentials directly on the NEAR blockchain using a smart contract.

Contract

• Network: testnet
• Contract ID: neardtiprooftype.testnet
• CID: The proof is the base64-encoded SHA-256 hash of the VC payload

Installation

Make sure near-api-js is available in your project.

npm install near-api-js

Usage

import{ProofTypeNear}from'./proof-type-near';import{connect,keyStores,WalletConnection}from'near-api-js';importCryptoJSfrom'crypto-js';constproofType=newProofTypeNear();constwallet: WalletConnection=/* your connected wallet */;constvcPayload={issuer: 'did:near:issuer.testnet',credentialSubject: {id: 'did:near:user.testnet',name: 'Alice'},issuanceDate: newDate().toISOString(),type: ['VerifiableCredential']};// Generate CID from VC payloadconstcid=CryptoJS.SHA256(JSON.stringify(vcPayload)).toString(CryptoJS.enc.Base64);// Generate on-chain proofconstproof=awaitproofType.generateProof(vcPayload,{
wallet,
cid
});// Verifyconstvalid=awaitproofType.verifyProof(proof);console.log(valid);// true or false

Notes

• The contract only allows a (did, cid) pair to be used once.
• The proof is linked to the NEAR account that issues the credential.