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https://github.com/dflydev/dflydev-hawk

Hawk — A PHP Implementation
https://github.com/dflydev/dflydev-hawk

Last synced: 9 months ago
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Hawk — A PHP Implementation

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README 

          
Hawk — A PHP Implementation

===========================



> Hawk is an HTTP authentication scheme using a message authentication code

> (MAC) algorithm to provide partial HTTP request cryptographic verification.

> — [hawk README][0]



Installation

------------



Through [Composer][1] as [dflydev/hawk][2].



Client

------



### Building a Client



The `Client` has a few required dependencies. It is generally easier to

construct a `Client` by using the `ClientBuilder`. A `Client` can be built

without setting anything to get sane defaults.



#### Simple ClientBuilder Example



```php

build()

```



#### Complete ClientBuilderExample



```php

setCrypto($crypto)

    ->setTimeProvider($timeProvider)

    ->setNonceProvider($nonceProvider)

    ->setLocaltimeOffset($localtimeOffset)

    ->build()

```



### Creating a Request



In order for a client to be able to sign a request, it needs to know the

credentials for the user making the request, the URL, method, and optionally

payload and content type of the request.



All available options include:



 * **payload**: The body of the request

 * **content_type**: The content-type for the request

 * **nonce**: If a specific nonce should be used in favor of one being generated

   automatically by the nonce provider.

 * **ext**: An ext value specific for this request

 * **app**: The app for this request ([Oz][3] specific)

 * **dlg**: The delegated-by value for this request ([Oz][3] specific)



#### Create Request Example



```php

createRequest(

    $credentials,

    'http://example.com/foo/bar?whatever',

    'POST',

    array(

        'payload' => 'hello world!',

        'content_type' => 'text/plain',

    )

);



// Assuming a hypothetical $headers object that can be used to add new headers

// to an outbound request, we can add the resulting 'Authorization' header

// for this Hawk request by doing:

$headers->set(

    $request->header()->fieldName(), // 'Authorization'

    $request->header()->fieldValue() // 'Hawk id="12345", mac="ad8c9f', ...'

);



```



#### The Client Request Object



The `Request` represents everything the client needs to know about a request

including a header and the artifacts that were used to create the request.



 * **header()**: A `Header` instance that represents the request

 * **artifacts()**: An `Artifacts` instance that contains the values that were

   used in creating the request



The **header** is required to be able to get the properly formatted Hawk

authorization header to send to the server. The **artifacts** are useful in the

case that authentication will be done on the server response.



### Authenticate Server Response



Hawk provides the ability for the client to authenticate a server response to

ensure that the response sent back is from the intended target.



All available options include:



 * **payload**: The body of the response

 * **content_type**: The content-type for the response



#### Authenticate Response Example



```php

get('Server-Authorization');



// We need to use the original credentials, the original request, the value

// for the 'Server-Authorization' header, and optionally the payload and

// content type of the response from the server.

$isAuthenticatedResponse = $client->authenticate(

    $credentials,

    $request,

    $header,

    array(

        'payload' => '{"message": "good day, sir!"}',

        'content_type' => 'application/json',

    )

);

```



### Complete Client Example



```php

build();



// Create a Hawk request based on making a POST request to a specific URL

// using a specific user's credentials. Also, we're expecting that we'll

// be sending a payload of 'hello world!' with a content-type of 'text/plain'.

$request = $client->createRequest(

    $credentials,

    'http://example.com/foo/bar?whatever',

    'POST',

    array(

        'payload' => 'hello world!',

        'content_type' => 'text/plain',

    )

);



// Ask a really useful fictional user agent to make a request; note that the

// request we are making here matches the details that we told the Hawk client

// about our request.

$response = Fictional\UserAgent::makeRequest(

    'POST',

    'http://example.com/foo/bar?whatever',

    array(

        'content_type' => 'text/plain',

        $request->header()->fieldName() => $request->header()->fieldValue(),

    ),

    'hello world!'

);



// This part is optional but recommended! At this point if we have a successful

// response we could just look at the content and be done with it. However, we

// are given the tools to authenticate the response to ensure that the response

// we were given came from the server we were expecting to be talking to.

$isAuthenticatedResponse = $client->authenticate(

    $credentials,

    $request,

    $response->headers->get('Server-Authorization'),

    array(

        'payload' => $response->getContent(),

        'content_type' => $response->headers->get('content-type'),

    )

);



if (!$isAuthenticatedResponse) {

    die("The server did a very bad thing...");

}



// Huzzah!

```



### Bewit



Hawk supports a method for granting third-parties temporary access to individual

resources using a query parameter called bewit.



The return value is a string that represents the bewit. This string should be

added to a requested URI by appending it to the end of the URI. If the URI has

query parameters already, the bewit should have `&bewit=` appended to the front

of it. If the URI does not have query parameters already, the bewit should

have `?bewit=` appended to the front of it.



#### Client Bewit Example



```php

createBewit(

    $credentials,

    'https://example.com/posts?foo=bar',

    300 // ttl in seconds

);

```



Server

------



### Building a Server



The `Server` has a few required dependencies. It is generally easier to

construct a `Server` by using the `ServerBuilder`. A `Server` can be built

without setting anything but the credentials provider to get sane defaults.



#### Simple ServerBuilder Example



```php

build()

```



#### Complete ServerBuilderExample



```php

setCrypto($crypto)

    ->setTimeProvider($timeProvider)

    ->setNonceValidator($nonceValidator)

    ->setTimestampSkewSec($timestampSkewSec)

    ->setLocaltimeOffsetSec($localtimeOffsetSec)

    ->build()

```



### Authenticating a Request



In order for a server to be able to authenticate a request, it needs to be able

to build the same MAC that the client did. It does this by getting the same

information about the request that the client knew about when it signed the

request.



In particular, the authorization header should include the ID. This ID is used

to retrieve the credentials (notably the key) in order to calculate the MAC

based on the rest of the request information.



#### Authenticate Example



```php

get('Authorization');



try {

    $response = $server->authenticate(

        'POST',

        'example.com',

        80,

        '/foo/bar?whatever',

        'text/plain',

        'hello world!'

        $authorization

    );

} catch(Dflydev\Hawk\Server\UnauthorizedException $e) {

    // If authorization is incorrect (invalid mac, etc.) we can catch an

    // unauthorized exception.

    throw $e;

}



// The credentials associated with this request. This is where one could access

// the ID for the user that made this request.

$credentials = $response->credentials();



// The artifacts associated with this request. This is where one could access

// things like the 'ext', 'app', and 'dlg' values sent with the request.

$artifacts = $response->artifacts();

```



#### The Server Response Object



The `Response` represents everything the server needs to know about a request

including the credentials and artifacts that are associated with the request.



 * **credentials()**

 * **artifacts()**



### Creating a Response Header



Hawk provides the ability for the server to sign the response to provide the

client with a way to authenticate a server response.



All available options include:



 * **payload**: The body of the request

 * **content_type**: The content-type for the request

 * **ext**: An ext value specific for this request



#### Create Response Header Example



```php

createHeader($credentials, $artifacts, array(

    'payload' => '{"message": "good day, sir!"}',

    'content_type' => 'application/json',

));



// Set the header using PHP's header() function.

header(sprintf("%s: %s", $header->fieldName(), $header->fieldValue()));

```



### Complete Server Example



```php

build()



// Get the authorization header for the request; it should be in the form

// of 'Hawk id="...", mac="...", [...]'

$authorization = $headers->get('Authorization');



try {

    $response = $server->authenticate(

        'POST',

        'example.com',

        80,

        '/foo/bar?whatever',

        'text/plain',

        'hello world!'

        $authorization

    );

} catch(Dflydev\Hawk\Server\UnauthorizedException $e) {

    // If authorization is incorrect (invalid mac, etc.) we can catch an

    // unauthorized exception.

    throw $e;

}



// Huzzah! Do something at this point with the request as we now know that

// it is an authenticated Hawk request.

//

// ...

//

// Ok we are done doing things! Assume based on what we did we ended up deciding

// the following payload and content type should be used:



$payload = '{"message": "good day, sir!"}';

$contentType = 'application/json';



// Create a Hawk header to sign our response

$header = $server->createHeader($credentials, $artifacts, array(

    'payload' => $payload,

    'content_type' => $contentType,

));



// Send some headers

header(sprintf("%s: %s", 'Content-Type', 'application/json'));

header(sprintf("%s: %s", $header->fieldName(), $header->fieldValue()));



// Output our payload

print $payload;

```



### Bewit



Hawk supports a method for granting third-parties temporary access to individual

resources using a query parameter called bewit.



Bewit authentication should only occur for `GET` and `HEAD` requests. The return

value of an authenticated bewit is a Server Response object.



#### Server Bewit Example



```php

authenticateBewit(

    'example.com',

    443,

    '/posts?bewit=ZXhxYlpXdHlrRlpJaDJEN2NYaTlkQVwxMzY4OTk2ODAwXE8wbWhwcmdvWHFGNDhEbHc1RldBV3ZWUUlwZ0dZc3FzWDc2dHBvNkt5cUk9XA'

);

```



Crypto

------



### Dflydev\Hawk\Crypto\Crypto



Tools for calculation of and comparison of MAC values.



 * **calculatePayloadHash($payload, $algorithm, $contentType)**

 * **calculateMac($type, CredentialsInterface $credentials, Artifacts $attributes)**

 * **calculateTsMac($ts, CredentialsInterface $credentials)**

 * **fixedTimeComparison($a, $b)**


   Used to ensure that the comparing two strings will always take the same amount

   of time regardless of whether they are the same or not.



### Dflydev\Hawk\Crypto\Artifacts



A container for all of the pieces of data that may go into the creation of a

MAC.



Credentials

-----------



### Dflydev\Hawk\Credentials\CredentialsInterface



Represents a valid set of credentials.



 * **key()**: Used to calculate the MAC

 * **algorithm()**: The algorithm used to calculate hashes

 * **id()**: An identifier (e.g. username) for whom the key belongs



In some contexts only the key may be known.



### Dflydev\Hawk\Credentials\Credentials



A simple implementation of `CredentialsInterface`.



```php



   Creates a Hawk header for a given field name for a set of attributes.

 * **createFromString($fieldName, $fieldValue, array $requiredKeys = null)**


   Creates a Hawk header for a given field name from a Hawk value string. For

   example, 'Hawk id="foo", mac="1234"' would be an example of a Hawk value

   string. This is useful for converting a header value coming in off the wire.



   Throws:



    * **Dflydev\Hawk\Header\FieldValueParserException**

    * **Dflydev\Hawk\Header\NotHawkAuthorizationException**



### Dflydev\Hawk\Header\HeaderParser



 * **parseFieldValue($fieldValue, array $requiredKeys = null)**


   Parses a field value string into an associative array of attributes.



   Throws:



    * **Dflydev\Hawk\Header\FieldValueParserException**

    * **Dflydev\Hawk\Header\NotHawkAuthorizationException**



### Dflydev\Hawk\Header\FieldValueParserException



Indicates that a string claims to be a Hawk string but it cannot be completely

parsed. This is mostly a sign of a corrupted or malformed header value.



### Dflydev\Hawk\Header\NotHawkAuthorizationException



Indicates that the string has nothing to do with Hawk. Currently means that the

string does not start with 'Hawk'.



License

-------



MIT, see LICENSE.



Community

---------



If you have questions or want to help out, join us in **#dflydev** on

**irc.freenode.net**.



[0]: https://github.com/hueniverse/hawk

[1]: http://getcomposer.org/

[2]: http://packagist.org/packages/dflydev/hawk

[3]: https://github.com/hueniverse/oz