# Cryptosign-based Authentication

Wampy.js supports cryptosign-based authentication. To use it you need to provide `authid`, `onChallenge` callback and `authextra` as wampy instance options. Also, Wampy.js supports `cryptosign` authentication method with a little helper plugin "[wampy-cryptosign](https://github.com/KSDaemon/wampy-cryptosign)". Just add "wampy-cryptosign" package and use provided methods as shown below.

The `authextra` option may contain the following properties for WAMP-Cryptosign:

<table><thead><tr><th width="179">Field</th><th width="94">Type</th><th width="102">Required</th><th width="380">Description</th></tr></thead><tbody><tr><td>pubkey</td><td>string</td><td>yes</td><td>The client public key (32 bytes) as a Hex encoded string, e.g. <code>545efb0a2192db8d43f118e9bf9aee081466e1ef36c708b96ee6f62dddad9122</code></td></tr><tr><td>channel_binding*</td><td>string</td><td>no</td><td>If TLS channel binding is in use, the TLS channel binding type, e.g. <code>"tls-unique"</code>.</td></tr><tr><td>challenge</td><td>string</td><td>no</td><td>A client chosen, random challenge (32 bytes) as a Hex encoded string, to be signed by the router.</td></tr><tr><td>trustroot</td><td>string</td><td>no</td><td>When the client includes a client certificate, the Ethereum address of the trustroot of the certificate chain to be used, e.g. <code>0x72b3486d38E9f49215b487CeAaDF27D6acf22115</code>, which can be a <em>Standalone Trustroot</em> or an <em>On-chain Trustroot</em></td></tr></tbody></table>

\*: `channel_binding` is not supported yet. And may be supported only in node.js environment.

```javascript
'use strict';

import { Wampy } from 'wampy';
import * as wampyCS from 'wampy-cryptosign';
// or you can import only sign method
//import { sign } from 'wampy-cryptosign';

/**
 * Manual authentication using signed message
 */
wampy = new Wampy('wss://wamp.router.url', {
    realm: 'realm1',
    authid: 'joe',
    authmethods: ['cryptosign'],
    authextra: {
        pubkey: '545efb0a2192db8d43f118e9bf9aee081466e1ef36c708b96ee6f62dddad9122'
    },
    onChallenge: (method, info) => {
        console.log('Requested challenge with ', method, info);
        return wampyCS.sign('joe secret (private) key')(method, info);
    }
});

/**
 * Promise-based manual authentication using signed message
 */
wampy = new Wampy('wss://wamp.router.url', {
    realm: 'realm1',
    authid: 'micky',
    authmethods: ['cryptosign'],
    authextra: {
        pubkey: '545efb0a2192db8d43f118e9bf9aee081466e1ef36c708b96ee6f62dddad9122'
    },
    onChallenge: (method, info) => {
        return new Promise((resolve, reject) => {
            setTimeout(() => {
                console.log('Requested challenge with ', method, info);
                resolve(wampyCS.sign('micky secret (private) key')(method, info));
            }, 2000);
        });
    }
});

/**
 * Automatic CryptoSign authentication
 */
wampy = new Wampy('wss://wamp.router.url', {
    realm: 'realm1',
    authid: 'patrik',
    authmethods: ['cryptosign'],
    authextra: {
        pubkey: '545efb0a2192db8d43f118e9bf9aee081466e1ef36c708b96ee6f62dddad9122'
    },
    onChallenge: wampyCS.sign('patrik secret (private) key')
});
```


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