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    @fastify/jwt
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    6.1.0 • Public • Published

    @fastify/jwt

    CI NPM version js-standard-style

    JWT utils for Fastify, internally it uses fast-jwt.

    NOTE: The plugin has been migrated from using jsonwebtoken to fast-jwt. Even though fast-jwt has 1:1 feature implementation with jsonwebtoken, some exotic implementations might break. In that case please open an issue with details of your implementation. See Upgrading notes for more details about what changes this migration introduced.

    @fastify/jwt supports Fastify@3. @fastify/jwt v1.x supports both Fastify@2.

    Install

    npm i @fastify/jwt --save
    

    Usage

    Register as a plugin. This will decorate your fastify instance with the following methods: decode, sign, and verify; refer to their documentation to find how to use the utilities. It will also register request.jwtVerify and reply.jwtSign. You must pass a secret when registering the plugin.

    const fastify = require('fastify')()
    fastify.register(require('@fastify/jwt'), {
      secret: 'supersecret'
    })
    
    fastify.post('/signup', (req, reply) => {
      // some code
      const token = fastify.jwt.sign({ payload })
      reply.send({ token })
    })
    
    fastify.listen(3000, err => {
      if (err) throw err
    })

    For verifying & accessing the decoded token inside your services, you can use a global onRequest hook to define the verification process like so:

    const fastify = require('fastify')()
    fastify.register(require('@fastify/jwt'), {
      secret: 'supersecret'
    })
    
    fastify.addHook("onRequest", async (request, reply) => {
      try {
        await request.jwtVerify()
      } catch (err) {
        reply.send(err)
      }
    })

    Afterwards, just use request.user in order to retrieve the user information:

    module.exports = async function(fastify, opts) {
      fastify.get("/", async function(request, reply) {
        return request.user
      })
    }

    However, most of the time we want to protect only some of the routes in our application. To achieve this you can wrap your authentication logic into a plugin like

    const fp = require("fastify-plugin")
    
    module.exports = fp(async function(fastify, opts) {
      fastify.register(require("@fastify/jwt"), {
        secret: "supersecret"
      })
    
      fastify.decorate("authenticate", async function(request, reply) {
        try {
          await request.jwtVerify()
        } catch (err) {
          reply.send(err)
        }
      })
    })

    Then use the onRequest of a route to protect it & access the user information inside:

    module.exports = async function(fastify, opts) {
      fastify.get(
        "/",
        {
          onRequest: [fastify.authenticate]
        },
        async function(request, reply) {
          return request.user
        }
      )
    }

    Make sure that you also check @fastify/auth plugin for composing more complex strategies.

    Auth0 tokens verification

    If you need to verify Auth0 issued HS256 or RS256 JWT tokens, you can use fastify-auth0-verify, which is based on top of this module.

    Options

    secret (required)

    You must pass a secret to the options parameter. The secret can be a primitive type String, a function that returns a String or an object { private, public }.

    In this object { private, public } the private key is a string, buffer or object containing either the secret for HMAC algorithms or the PEM encoded private key for RSA and ECDSA. In case of a private key with passphrase an object { private: { key, passphrase }, public } can be used (based on crypto documentation), in this case be sure you pass the algorithm inside the signing options prefixed by the sign key of the plugin registering options).

    In this object { private, public } the public key is a string or buffer containing either the secret for HMAC algorithms, or the PEM encoded public key for RSA and ECDSA.

    Function based secret is supported by the request.jwtVerify() and reply.jwtSign() methods and is called with request, token, and callback parameters.

    Example

    const { readFileSync } = require('fs')
    const path = require('path')
    const fastify = require('fastify')()
    const jwt = require('@fastify/jwt')
    // secret as a string
    fastify.register(jwt, { secret: 'supersecret' })
    // secret as a function with callback
    fastify.register(jwt, {
      secret: function (request, token, callback) {
        // do something
        callback(null, 'supersecret')
      }
    })
    // secret as a function returning a promise
    fastify.register(jwt, {
      secret: function (request, token) {
        return Promise.resolve('supersecret')
      }
    })
    // secret as an async function
    fastify.register(jwt, {
      secret: async function (request, token) {
        return 'supersecret'
      }
    })
    // secret as an object of RSA keys (without passphrase)
    // the files are loaded as strings
    fastify.register(jwt, {
      secret: {
        private: readFileSync(`${path.join(__dirname, 'certs')}/private.key`, 'utf8'),
        public: readFileSync(`${path.join(__dirname, 'certs')}/public.key`, 'utf8')
      },
      sign: { algorithm: 'RS256' }
    })
    // secret as an object of P-256 ECDSA keys (with a passphrase)
    // the files are loaded as buffers
    fastify.register(jwt, {
      secret: {
        private: {
          key: readFileSync(`${path.join(__dirname, 'certs')}/private.pem`),
          passphrase: 'super secret passphrase'
        },
        public: readFileSync(`${path.join(__dirname, 'certs')}/public.pem`)
      },
      sign: { algorithm: 'ES256' }
    })

    Optionally you can define global default options that will be used by @fastify/jwt API if you do not override them.

    Additionally, it is also possible to reject tokens selectively (i.e. blacklisting) by providing the option trusted with the following signature: (request, decodedToken) => boolean|Promise<boolean>|SignPayloadType|Promise<SignPayloadType> where request is a FastifyRequest and decodedToken is the parsed (and verified) token information. Its result should be false or Promise<false> if the token should be rejected or, otherwise, be true or Promise<true> if the token should be accepted and, considering that request.user will be used after that, the return should be decodedToken itself.

    Example

    const { readFileSync } = require('fs')
    const path = require('path')
    const fastify = require('fastify')()
    const jwt = require('@fastify/jwt')
    fastify.register(jwt, {
      secret: {
        private: readFileSync(`${path.join(__dirname, 'certs')}/private.pem`, 'utf8')
        public: readFileSync(`${path.join(__dirname, 'certs')}/public.pem`, 'utf8')
      },
      // Global default decoding method options
      decode: { complete: true },
      // Global default signing method options
      sign: {
        algorithm: 'ES256',
        iss: 'api.example.tld'
      },
      // Global default verifying method options
      verify: { allowedIss: 'api.example.tld' }
    })
    
    fastify.get('/decode', async (request, reply) => {
      // We clone the global signing options before modifying them
      let altSignOptions = Object.assign({}, fastify.jwt.options.sign)
      altSignOptions.iss = 'another.example.tld'
    
      // We generate a token using the default sign options
      const token = await reply.jwtSign({ foo: 'bar' })
      // We generate a token using overrided options
      const tokenAlt = await reply.jwtSign({ foo: 'bar' }, altSignOptions)
    
      // We decode the token using the default options
      const decodedToken = fastify.jwt.decode(token)
    
      // We decode the token using completely overided the default options
      const decodedTokenAlt = fastify.jwt.decode(tokenAlt, { complete: false })
    
      return { decodedToken, decodedTokenAlt }
      /**
       * Will return:
       *
       * {
       *   "decodedToken": {
       *     "header": {
       *       "alg": "ES256",
       *       "typ": "JWT"
       *     },
       *     "payload": {
       *       "foo": "bar",
       *       "iat": 1540305336
       *       "iss": "api.example.tld"
       *     },
       *     "signature": "gVf5bzROYB4nPgQC0nbJTWCiJ3Ya51cyuP-N50cidYo"
       *   },
       *   decodedTokenAlt: {
       *     "foo": "bar",
       *     "iat": 1540305337
       *     "iss": "another.example.tld"
       *   },
       * }
       */
    })
    
    fastify.listen(3000, err => {
      if (err) throw err
    })

    cookie

    Example using cookie

    In some situations you may want to store a token in a cookie. This allows you to drastically reduce the attack surface of XSS on your web app with the httpOnly and secure flags. Cookies can be susceptible to CSRF. You can mitigate this by either setting the sameSite flag to strict, or by using a CSRF library such as @fastify/csrf.

    Note: This plugin will look for a decorated request with the cookies property. @fastify/cookie supports this feature, and therefore you should use it when using the cookie feature. The plugin will fallback to looking for the token in the authorization header if either of the following happens (even if the cookie option is enabled):

    • The request has both the authorization and cookie header
    • Cookie is empty, authorization header is present

    If you are signing your cookie, you can set the signed boolean to true which will make sure the JWT is verified using the unsigned value.

    const fastify = require('fastify')()
    const jwt = require('@fastify/jwt')
    
    fastify.register(jwt, {
      secret: 'foobar'
      cookie: {
        cookieName: 'token',
        signed: false
      }
    })
    
    fastify
      .register(require('@fastify/cookie'))
    
    fastify.get('/cookies', async (request, reply) => {
      const token = await reply.jwtSign({
        name: 'foo',
        role: ['admin', 'spy']
      })
    
      reply
        .setCookie('token', token, {
          domain: 'your.domain',
          path: '/',
          secure: true, // send cookie over HTTPS only
          httpOnly: true,
          sameSite: true // alternative CSRF protection
        })
        .code(200)
        .send('Cookie sent')
    })
    
    fastify.addHook('onRequest', (request) => request.jwtVerify())
    
    fastify.get('/verifycookie', (request, reply) => {
      reply.send({ code: 'OK', message: 'it works!' })
    })
    
    fastify.listen(3000, err => {
      if (err) throw err
    })

    trusted

    Example trusted tokens

    const fastify = require('fastify')()
    
    fastify.register(require('@fastify/jwt'), {
      secret: 'foobar',
      trusted: validateToken
    })
    
    fastify.addHook('onRequest', (request) => request.jwtVerify())
    
    fastify.get('/', (request, reply) => {
      reply.send({ code: 'OK', message: 'it works!' })
    })
    
    fastify.listen(3000, (err) => {
      if (err) {
        throw err
      }
    })
    
    // ideally this function would do a query against some sort of storage to determine its outcome
    async function validateToken(request, decodedToken) {
      const denylist = ['token1', 'token2']
    
      return !denylist.includes(decodedToken.jti)
    }

    formatUser

    Example with formatted user

    You may customize the request.user object setting a custom sync function as parameter:

    const fastify = require('fastify')();
    fastify.register(require('@fastify/jwt'), {
      formatUser: function (user) {
        return {
          departmentName: user.department_name,
          name: user.name
        }
      },
      secret: 'supersecret'
    });
    
    fastify.addHook('onRequest', (request, reply) =>  request.jwtVerify());
    
    fastify.get("/", async (request, reply) => {
      return `Hello, ${request.user.name} from ${request.user.departmentName}.`;
    });

    namespace

    To define multiple JWT validators on the same routes, you may use the namespace option. You can combine this with custom names for jwtVerify and jwtSign.

    When you omit the jwtVerify and jwtSign options, the default function name will be <namespace>JwtVerify and <namespace>JwtSign.

    Example with namespace

    const fastify = require('fastify')
    
    fastify.register(jwt, {
      secret: 'test',
      namespace: 'security',
      jwtVerify: 'securityVerify',
      jwtSign: 'securitySign'
    })
    
    fastify.register(jwt, {
      secret: 'fastify',
      namespace: 'airDrop'
    })
    
    // use them like this:
    fastify.post('/sign/:namespace', async function (request, reply) {
      switch (request.params.namespace) {
        case 'security':
          return reply.securitySign(request.body)
        default:
          return reply.airDropJwtSign(request.body)
      }
    })

    messages

    For your convenience, you can override the default HTTP response messages sent when an unauthorized or bad request error occurs. You can choose the specific messages to override and the rest will fallback to the default messages. The object must be in the format specified in the example below.

    Example

    const fastify = require('fastify')
    
    const myCustomMessages = {
      badRequestErrorMessage: 'Format is Authorization: Bearer [token]',
      noAuthorizationInHeaderMessage: 'Autorization header is missing!',
      authorizationTokenExpiredMessage: 'Authorization token expired',
      // for the below message you can pass a sync function that must return a string as shown or a string
      authorizationTokenInvalid: (err) => {
        return `Authorization token is invalid: ${err.message}`
      }
    }
    
    fastify.register(require('@fastify/jwt'), {
      secret: 'supersecret',
      messages: myCustomMessages
    })

    decoratorName

    If this plugin is used together with fastify/passport, we might get an error as both plugins use the same name for a decorator. We can change the name of the decorator, or user will default

    Example

    const fastify = require('fastify')
    fastify.register(require('@fastify/jwt'), {
      secret: 'supersecret',
      decoratorName: 'customName'
    })

    decode

    • complete: Return an object with the decoded header, payload, signature and input (the token part before the signature), instead of just the content of the payload. Default is false.
    • checkTyp: When validating the decoded header, setting this option forces the check of the typ property against this value. Example: checkTyp: 'JWT'. Default is undefined.

    sign

    • key: A string or a buffer containing the secret for HS* algorithms or the PEM encoded public key for RS*, PS*, ES* and EdDSA algorithms. The key can also be a function accepting a Node style callback or a function returning a promise. If provided, it will override the value of secret provided in the options.

    • algorithm: The algorithm to use to sign the token. The default is autodetected from the key, using RS256 for RSA private keys, HS256 for plain secrets and the correspondent ES or EdDSA algorithms for EC or Ed* private keys.

    • mutatePayload: If set to true, the original payload will be modified in place (via Object.assign) by the signing function. This is useful if you need a raw reference to the payload after claims have been applied to it but before it has been encoded into a token.

    • expiresIn: Time span after which the token expires, added as the exp claim in the payload. It is expressed in seconds or a string describing a time span (E.g.: 60, "2 days", "10h", "7d"). A numeric value is interpreted as a seconds count. If you use a string be sure you provide the time units (days, hours, etc.), otherwise milliseconds unit is used by default ("120" is equal to "120ms"). This will override any existing value in the claim.

    • notBefore: Time span before the token is active, added as the nbf claim in the payload. It is expressed in seconds or a string describing a time span (E.g.: 60, "2 days", "10h", "7d"). A numeric value is interpreted as a seconds count. If you use a string be sure you provide the time units (days, hours, etc.), otherwise milliseconds unit is used by default ("120" is equal to "120ms"). This will override any existing value in the claim.

    • ... the rest of the sign options can be found here.

    verify

    • key: A string or a buffer containing the secret for HS* algorithms or the PEM encoded public key for RS*, PS*, ES* and EdDSA algorithms. The key can also be a function accepting a Node style callback or a function returning a promise. If provided, it will override the value of secret provided in the options.
    • algorithms: List of strings with the names of the allowed algorithms. By default, all algorithms are accepted.
    • complete: Return an object with the decoded header, payload, signature and input (the token part before the signature), instead of just the content of the payload. Default is false.
    • cache: A positive number specifying the size of the verified tokens cache (using LRU strategy). Setting this to true is equivalent to provide the size 1000. When enabled the performance is dramatically improved. By default the cache is disabled.
    • cacheTTL: The maximum time to live of a cache entry (in milliseconds). If the token has a earlier expiration or the verifier has a shorter maxAge, the earlier takes precedence. The default is 600000, which is 10 minutes.
    • maxAge: The maximum allowed age for tokens to still be valid. It is expressed in seconds or a string describing a time span (E.g.: 60, "2 days", "10h", "7d"). A numeric value is interpreted as a seconds count. If you use a string be sure you provide the time units (days, hours, etc.), otherwise milliseconds unit is used by default ("120" is equal to "120ms"). By default this is not checked.
    • ... the rest of the verify options can be found here.

    API Spec

    fastify.jwt.sign(payload [,options] [,callback])

    This method is used to sign the provided payload. It returns the token. The payload must be an Object. Can be used asynchronously by passing a callback function; synchronously without a callback. options must be an Object and can contain sign options.

    fastify.jwt.verify(token, [,options] [,callback])

    This method is used to verify provided token. It accepts a token (as Buffer or a string) and returns the payload or the sections of the token. Can be used asynchronously by passing a callback function; synchronously without a callback. options must be an Object and can contain verify options.

    Example

    const token = fastify.jwt.sign({ foo: 'bar' })
    // synchronously
    const decoded = fastify.jwt.verify(token)
    // asycnhronously
    fastify.jwt.verify(token, (err, decoded) => {
      if (err) fastify.log.error(err)
      fastify.log.info(`Token verified. Foo is ${decoded.foo}`)
    })

    fastify.jwt.decode(token [,options])

    This method is used to decode the provided token. It accepts a token (as a Buffer or a string) and returns the payload or the sections of the token. options must be an Object and can contain decode options. Can only be used synchronously.

    Example

    const token = fastify.jwt.sign({ foo: 'bar' })
    const decoded = fastify.jwt.decode(token)
    fastify.log.info(`Decoded JWT: ${decoded}`)

    fastify.jwt.options

    For your convenience, the decode, sign, verify and messages options you specify during .register are made available via fastify.jwt.options that will return an object { decode, sign, verify, messages } containing your options.

    Example

    const { readFileSync } = require('fs')
    const path = require('path')
    const fastify = require('fastify')()
    const jwt = require('@fastify/jwt')
    fastify.register(jwt, {
      secret: {
        private: readFileSync(`${path.join(__dirname, 'certs')}/private.key`),
        public: readFileSync(`${path.join(__dirname, 'certs')}/public.key`)
      },
      sign: {
        algorithm: 'RS256',
        aud: 'foo',
        iss: 'example.tld'
      },
      verify: {
        allowedAud: 'foo',
        allowedIss: 'example.tld',
      }
    })
    
    fastify.get('/', (request, reply) => {
      const globalOptions = fastify.jwt.options
    
      // We recommend that you clone the options like this when you need to mutate them
      // modifiedVerifyOptions = { audience: 'foo', issuer: 'example.tld' }
      let modifiedVerifyOptions = Object.assign({}, fastify.jwt.options.verify)
      modifiedVerifyOptions.allowedAud = 'bar'
      modifiedVerifyOptions.allowedSub = 'test'
    
      return { globalOptions, modifiedVerifyOptions }
      /**
       * Will return :
       * {
       *   globalOptions: {
       *     decode: {},
       *     sign: {
       *       algorithm: 'RS256',
       *       aud: 'foo',
       *       iss: 'example.tld'
       *     },
       *     verify: {
       *       allowedAud: 'foo',
       *       allowedIss: 'example.tld'
       *     }
       *   },
       *   modifiedVerifyOptions: {
       *     allowedAud: 'bar',
       *     allowedIss: 'example.tld',
       *     allowedSub: 'test'
       *   }
       * }
       */
    })
    
    fastify.listen(3000, err => {
      if (err) throw err
    })

    fastify.jwt.cookie

    For your convenience, request.jwtVerify() will look for the token in the cookies property of the decorated request. You must specify cookieName. Refer to the cookie example to see sample usage and important caveats.

    reply.jwtSign(payload, [options,] callback)

    options must be an Object and can contain sign options.

    request.jwtVerify([options,] callback)

    options must be an Object and can contain verify and decode options.

    request.jwtDecode([options,] callback)

    Decode a JWT without verifying

    As of 3.2.0, decorated when options.jwtDecode is truthy. Will become non-conditionally decorated in 4.0.0. This avoid breaking change that would effect fastify-auth0-verify.

    options must be an Object and can contain verify and decode options.

    Algorithms supported

    The following algorithms are currently supported by fast-jwt that is internally used by @fastify/jwt.

    Name Description
    none Empty algorithm - The token signature section will be empty
    HS256 HMAC using SHA-256 hash algorithm
    HS384 HMAC using SHA-384 hash algorithm
    HS512 HMAC using SHA-512 hash algorithm
    ES256 ECDSA using P-256 curve and SHA-256 hash algorithm
    ES384 ECDSA using P-384 curve and SHA-384 hash algorithm
    ES512 ECDSA using P-521 curve and SHA-512 hash algorithm
    RS256 RSASSA-PKCS1-v1_5 using SHA-256 hash algorithm
    RS384 RSASSA-PKCS1-v1_5 using SHA-384 hash algorithm
    RS512 RSASSA-PKCS1-v1_5 using SHA-512 hash algorithm
    PS256 RSASSA-PSS using SHA-256 hash algorithm
    PS384 RSASSA-PSS using SHA-384 hash algorithm
    PS512 RSASSA-PSS using SHA-512 hash algorithm
    EdDSA EdDSA tokens using Ed25519 or Ed448 keys, only supported on Node.js 12+

    You can find the list here.

    Examples

    Certificates Generation

    Here some example on how to generate certificates and use them, with or without passphrase.

    Signing and verifying (jwtSign, jwtVerify)

    const fastify = require('fastify')()
    const jwt = require('@fastify/jwt')
    const request = require('request')
    
    fastify.register(jwt, {
      secret: function (request, reply, callback) {
        // do something
        callback(null, 'supersecret')
      }
    })
    
    fastify.post('/sign', function (request, reply) {
      reply.jwtSign(request.body.payload, function (err, token) {
        return reply.send(err || { 'token': token })
      })
    })
    
    fastify.get('/verify', function (request, reply) {
      request.jwtVerify(function (err, decoded) {
        return reply.send(err || decoded)
      })
    })
    
    fastify.listen(3000, function (err) {
      if (err) fastify.log.error(err)
      fastify.log.info(`Server live on port: ${fastify.server.address().port}`)
    
      // sign payload and get JWT
      request({
        method: 'POST',
        headers: {
          'Content-Type': 'application/json'
        },
        body: {
          payload: {
            foo: 'bar'
          }
        },
        uri: `http://localhost:${fastify.server.address().port}/sign`,
        json: true
      }, function (err, response, body) {
        if (err) fastify.log.error(err)
        fastify.log.info(`JWT token is ${body.token}`)
    
        // verify JWT
        request({
          method: 'GET',
          headers: {
            'Content-Type': 'application/json',
            authorization: 'Bearer ' + body.token
          },
          uri: 'http://localhost:' + fastify.server.address().port + '/verify',
          json: true
        }, function (err, response, body) {
          if (err) fastify.log.error(err)
          fastify.log.info(`JWT verified. Foo is ${body.foo}`)
        })
      })
    })

    Verifying with JWKS

    The following example integrates the get-jwks package to fetch a JWKS and verify a JWT against a valid public JWK.

    Example
    const Fastify = require('fastify')
    const fjwt = require('@fastify/jwt')
    const buildGetJwks = require('get-jwks')
    
    const fastify = Fastify()
    const getJwks = buildGetJwks()
    
    fastify.register(fjwt, {
      decode: { complete: true },
      secret: (request, token) => {
        const { header: { kid, alg }, payload: { iss } } = token
        return getJwks.getPublicKey({ kid, domain: iss, alg })
      }
    })
    
    fastify.addHook('onRequest', async (request, reply) => {
      try {
        await request.jwtVerify()
      } catch (err) {
        reply.send(err)
      }
    })
    
    fastify.listen(3000)

    TypeScript

    This plugin has two available exports, the default plugin function fastifyJwt and the plugin options object FastifyJWTOptions.

    Import them like so:

    import fastifyJwt, { FastifyJWTOptions } from '@fastify/jwt'

    Define custom Payload Type and Attached User Type to request object

    typescript declaration merging

    // fastify-jwt.d.ts
    import "@fastify/jwt"
    
    declare module "@fastify/jwt" {
      interface FastifyJWT {
        payload: { id: number } // payload type is used for signing and verifying
        user: {
          id: number,
          name: string,
          age: number
          } // user type is return type of `request.user` object
      }
    }
    
    // index.ts
    fastify.get('/', async (request, reply) => {
      request.user.name // string
    
      const token = await reply.jwtSign({
        id: '123'
        // ^ Type 'string' is not assignable to type 'number'.
      });
    })

    Acknowledgements

    This project is kindly sponsored by:

    License

    Licensed under MIT.

    Install

    npm i @fastify/jwt

    DownloadsWeekly Downloads

    14,297

    Version

    6.1.0

    License

    MIT

    Unpacked Size

    141 kB

    Total Files

    16

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