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jwt-simple.ts
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jwt-simple.ts
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/**
* Ported to Typescript from original implementation below:
* https://github.com/hokaccha/node-jwt-simple -- MIT licensed
*/
/**
* module dependencies
*/
import { bytesToUtf8, utf8ToBytes } from '@ethereumjs/util'
import { base64url } from '@scure/base'
import crypto from 'crypto'
/**
* support algorithm mapping
*/
export type TAlgorithm = 'HS256' | 'HS384' | 'HS512' | 'RS256'
const algorithmMap: Record<string, string> = {
HS256: 'sha256',
HS384: 'sha384',
HS512: 'sha512',
RS256: 'RSA-SHA256',
}
/**
* Map algorithm to hmac or sign type, to determine which crypto function to use
*/
const typeMap: Record<string, string> = {
HS256: 'hmac',
HS384: 'hmac',
HS512: 'hmac',
RS256: 'sign',
}
/**
* expose object
*/
/**
* private util functions
*/
function assignProperties(dest: any, source: any) {
for (const [attr] of Object.entries(source)) {
if (Object.prototype.hasOwnProperty.call(source, attr)) {
dest[attr] = source[attr]
}
}
}
function assertAlgorithm(alg: any): asserts alg is Algorithm {
if (!['HS256', 'HS384', 'HS512', 'RS256'].includes(alg)) {
throw new Error('Algorithm not supported')
}
}
function base64urlUnescape(str: string) {
str += new Array(5 - (str.length % 4)).join('=')
return str.replace(/-/g, '+').replace(/_/g, '/')
}
function base64urlEscape(str: string) {
return str.replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '')
}
function sign(input: any, key: string, method: string, type: string) {
let base64str
if (type === 'hmac') {
base64str = crypto.createHmac(method, key).update(input).digest('base64')
} else if (type === 'sign') {
base64str = crypto.createSign(method).update(input).sign(key, 'base64')
} else {
throw new Error('Algorithm type not recognized')
}
return base64urlEscape(base64str)
}
function verify(input: any, key: string, method: string, type: string, signature: string) {
if (type === 'hmac') {
return signature === sign(input, key, method, type)
} else if (type === 'sign') {
return crypto
.createVerify(method)
.update(input)
.verify(key, base64urlUnescape(signature), 'base64')
} else {
throw new Error('Algorithm type not recognized')
}
}
/**
* Decode jwt
*
* @param {Object} token
* @param {String} key
* @param {Boolean} [noVerify]
* @param {String} [algorithm]
* @return {Object} payload
* @api public
*/
const decode = function jwt_decode(
token: string,
key: string,
noVerify: boolean = false,
algorithm: string = ''
) {
// check token
if (!token) {
throw new Error('No token supplied')
}
// check segments
const segments = token.split('.')
if (segments.length !== 3) {
throw new Error('Not enough or too many segments')
}
// All segment should be base64
const headerSeg = segments[0]
const payloadSeg = segments[1]
const signatureSeg = segments[2]
// base64 decode and parse JSON
const header = JSON.parse(bytesToUtf8(base64url.decode(headerSeg)))
const payload = JSON.parse(bytesToUtf8(base64url.decode(payloadSeg)))
if (!noVerify) {
if (!algorithm && /BEGIN( RSA)? PUBLIC KEY/.test(key.toString())) {
algorithm = 'RS256'
}
algorithm = algorithm || header.alg
assertAlgorithm(algorithm)
const signingMethod = algorithmMap[algorithm]
const signingType = typeMap[algorithm]
// verify signature. `sign` will return base64 string.
const signingInput = [headerSeg, payloadSeg].join('.')
if (verify(signingInput, key, signingMethod, signingType, signatureSeg) === false) {
throw new Error('Signature verification failed')
}
// Support for nbf and exp claims.
// According to the RFC, they should be in seconds.
if (payload.nbf !== undefined && Date.now() < payload.nbf * 1000) {
throw new Error('Token not yet active')
}
if (payload.exp !== undefined && Date.now() > payload.exp * 1000) {
throw new Error('Token expired')
}
}
return payload
}
/**
* Encode jwt
*
* @param {Object} payload
* @param {String} key
* @param {String} algorithm
* @param {Object} options
* @return {String} token
* @api public
*/
const encode = function jwt_encode(
payload: any,
key: string,
algorithm: string = '',
options: any = undefined
) {
// Check key
if (!key) {
throw new Error('Require key')
}
// Check algorithm, default is HS256
if (!algorithm) {
algorithm = 'HS256'
}
assertAlgorithm(algorithm)
const signingMethod = algorithmMap[algorithm]
const signingType = typeMap[algorithm]
// header, typ is fixed value.
const header = { typ: 'JWT', alg: algorithm }
if (options !== undefined && options.header !== undefined) {
assignProperties(header, options.header)
}
// create segments, all segments should be base64 string
const segments = []
segments.push(base64url.encode(utf8ToBytes(JSON.stringify(header))))
segments.push(base64url.encode(utf8ToBytes(JSON.stringify(payload))))
segments.push(sign(segments.join('.'), key, signingMethod, signingType))
return segments.join('.')
}
export const jwt = { encode, decode }