index.md

title	index	category	type	source
Working with JWT's	4	did-jwt	guide	https://github.com/uport-project/did-jwt/blob/develop/docs/guides/index.md

Working with did-JWT's

Creating a JWT

Use the createJWT() function

import { createJWT, SimpleSigner } from 'did-jwt'

const signer = SimpleSigner('PRIVATEKEY')

createJWT(
    {aud: 'did:uport:2nQtiQG6Cgm1GYTBaaKAgr76uY7iSexUkqY', exp: 1485321133, name: 'Bob Smith'},
    {issuer: 'did:uport:2nQtiQG6Cgm1GYTBaaKAgr76uY7iSexUkqX', signer}).then(jwt => {
    console.log(jwt)
})

Parameters

createJWT(payload, options, header)

Name	Description	Required
payload	an object containing any claims you want to encode in the JWT including optional standard claims such as sub, aud and exp	yes
options.issuer	The DID of the issuer of the JWT	yes
options.signer	A signing function (see SimpleSigner)	yes
options.expiresIn	How many seconds after signing should the JWT be valid (sets the exp claim)	no
header	Object to inject custom headers, e.g. alg or cty	no

Promise Return Value

The createJWT() function returns a Promise.

A successfull call returns an object containing the following attributes:

Name	Description
jwt	String containing a JSON Web Tokens (JWT)

If there are any errors found during the signing process the promise is rejected with a clear error message.

Verifying a JWT

Use the verifyJWT() function

import { verifyJWT } from 'did-jwt'

verifyJWT('eyJ0eXAiOiJKV1QiLCJhbGciOiJFUzI1NksifQ.eyJpc3MiOiJkaWQ6dXBvcn....', {audience: 'Your DID'}).then({payload, doc, did, signer, jwt} => {
    console.log(payload)
})

Parameters

verifyJWT(jwt, options)

Name	Description	Required
jwt	String containing a JSON Web Tokens (JWT)	yes
options.auth	Require signer to be listed in the authentication section of the DID document (for Authentication of a user with DID-AUTH)
options.audience	The DID of the audience of the JWT	no
options.callbackUrl	The the URL receiving the JWT	no

Promise Return Value

The verifyJWT() function returns a Promise.

A successfull call returns an object containing the following attributes:

Name	Description
payload	An object containing the JSON parsed contents of the payload section of the JWT
issuer	The DID of the issuer of the JWT
signer	An object containing information about which key signed the JWT. This is useful if a DID document has multiple keys listed
doc	The DID Document of the issuer of the JWT
jwt	The original JWT passed in to the function

If there are any errors found during the verification process the promise is rejected with a clear error message.

Signer Functions

We provide a simple signing abstraction that makes it easy to add support for your own Key Management infrastructure.

SimpleSigner

For most people you can use our SimpleSigner() function to create a signer function using a hex encoded private key.

import { SimpleSigner } from 'did-jwt'
const signer = SimpleSigner('278a5de700e29faae8e40e366ec5012b5ec63d36ec77e8a2417154cc1d25383f')

Parameters

SimpleSigner(prdivateKey)

Name	Description	Required
privateKey	hex encoded secp256k1 privatekey	yes

Note this is NOT a constructor, but a higher order function that returns a signing function.

Creating Custom Signers for integrating with HSM

You can easily create custom signers that integrates into your existing signing infrastructure. A signer function takes the raw data to be signed and returns a Promise containing the signature parameters.

function mySigner (data) {
    return new Promise((resolve, reject) => {
        const signature = /// sign it
        resolve(signature)
    })
}

Parameters

Name	Description	Required
data	String or Buffer containing data to be signed	yes

Promise Return Value

Your function must returns a Promise.

A successfull call returns an object containing the following attributes:

Name	Description	Required
r	Hex encoded r value of secp256k1 signature	yes
s	Hex encoded s value of secp256k1 signature	yes
recoveryParam	Recovery parameter of signature (can be used to calculate signing public key)	only required for (ES256K-R)