Code information details of the Koa JWT authentication plug-in developed by KoaHub based on Node.js

Koa middleware that validates JSON Web Tokens and sets ctx.state.user (by default) if a valid token is provided.
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koa-jwt

Koa JWT authentication middleware.

koa-jwt

Koa middleware that validates JSON Web Tokens and sets ctx.state.user (by default) if a valid token is provided.
This module lets you authenticate HTTP requests using JSON Web Tokens in your Koa (node.js) applications.
See this article for a good introduction.
Install$ npm install koa-jwtUsage
The JWT authentication middleware authenticates callers using a JWT token. If the token is valid, ctx.state.user (by default) will be set with the JSON object decoded to be used by later middleware for authorization and access control.
The token is normally provided in a HTTP header (Authorization), but it can also be provided in a cookie by setting the opts.cookie option to the name of the cookie that contains the token. Custom token retrieval can also be done through the opts.getToken option. The provided function is called in the normal Koa context and should return the retrieved token.
Normally you provide a single shared secret in opts.secret, but another alternative is to have an earlier middleware set ctx.state.secret, typically per request. If this property exists, it will be used instead of the one in opts.secret.

Examplevar koa = require('koa');
var jwt = require('koa-jwt');
 
var app = koa();
 
// Custom 401 handling if you don't want to expose koa-jwt errors to users 
app.use(function *(next){
  try {
    yield next;
  } catch (err) {
    if (401 == err.status) {
      this.status = 401;
      this.body = 'Protected resource, use Authorization header to get accessn';
    } else {
      throw err;
    }
  }
});
 
// Unprotected middleware 
app.use(function *(next){
  if (this.url.match(/^/public/)) {
    this.body = 'unprotectedn';
  } else {
    yield next;
  }
});
 
// Middleware below this line is only reached if JWT token is valid 
app.use(jwt({ secret: 'shared-secret' }));
 
// Protected middleware 
app.use(function *(){
  if (this.url.match(/^/api/)) {
    this.body = 'protectedn';
  }
});
 
app.listen(3000);
Alternatively you can conditionally run the jwt middleware under certain conditions:var koa = require('koa');
var jwt = require('koa-jwt');
 
var app = koa();
 
// Middleware below this line is only reached if JWT token is valid 
// unless the URL starts with '/public' 
app.use(jwt({ secret: 'shared-secret' }).unless({ path: [/^/public/] }));
 
// Unprotected middleware 
app.use(function *(next){
  if (this.url.match(/^/public/)) {
    this.body = 'unprotectedn';
  } else {
    yield next;
  }
});
 
// Protected middleware 
app.use(function *(){
  if (this.url.match(/^/api/)) {
    this.body = 'protectedn';
  }
});
 
app.listen(3000);
For more information on unless exceptions, check koa-unless.
You can also add the passthrough option to always yield next, even if no valid Authorization header was found:app.use(jwt({ secret: 'shared-secret', passthrough: true }));This lets downstream middleware make decisions based on whether ctx.state.user is set.
If you prefer to use another ctx key for the decoded data, just pass in key, like so:app.use(jwt({ secret: 'shared-secret', key: 'jwtdata' }));
This makes the decoded data available as ctx.state.jwtdata.
You can specify audience and/or issuer as well:app.use(jwt({ secret:   'shared-secret',
              audience: 'http://myapi/protected',
              issuer:   'http://issuer' }));If the JWT has an expiration (exp), it will be checked.
This module also support tokens signed with public/private key pairs. Instead of a secret, you can specify a Buffer with the public key:
var publicKey = fs.readFileSync('/path/to/public.pub');
app.use(jwt({ secret: publicKey }));
Related Modules
jsonwebtoken — JSON Web Token signing and verification
Note that koa-jwt exports the sign, verify and decode functions from the above module as a convenience.
Tests
$ npm install
$ npm test
Author
Stian Grytøyr
Credits
This code is largely based on express-jwt.
Auth0
Matias Woloski
Contributors
Foxandxss
soygul
tunnckoCore
getuliojr
cesarandreu
michaelwestphal
sc0ttyd
Jackong
danwkennedy
Licens
The MIT License

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代码来源：http://js.koahub.com/home/feature/koa-jwt