https://github.com/themizzi/Custom-Magento-Rest-Api2
https://www.magentocommerce.com/magento-connect/rest-api-oauth-direct-login-extension.html

<?php
class Custom_Restapi_Model_Api2_Restapi_Rest_Guest_V1 extends Custom_Restapi_Model_Api2_Restapi
{

    /**
     * Create a customer
     * @return array
     */

    public function _create(array $data) {

        $firstName = $data['firstname'];
        $lastName = $data['lastname'];
        $email = $data['email'];
        $password = $data['password'];

        $customer = Mage::getModel("customer/customer");

        $customer->setFirstname($firstName);
        $customer->setLastname($lastName);
        $customer->setEmail($email);
        $customer->setPasswordHash(md5($password));
        $customer->save();
        //return json_encode(array("testing","Success"));
        //return $customer->getId();

        //return $this->_getLocation($customer);


        $oauthConsumerKey='0167229419fcc5de3cfac3ff9062csdf402';
        $oauthConsumerSecret='afba22feae63538e99s05399698sdfd621da';
        $username=$email;
        $password=$password;
        $baseurl='http://localhost/my_magento/';
        //initiate
        $realm = $baseurl;
        $endpointUrl = $realm."oauth/initiate";
        $oauthCallback = $baseurl;
        $oauthNonce = uniqid(mt_rand(1, 1000));
        $oauthSignatureMethod = "HMAC-SHA1";
        $oauthTimestamp = time();
        $oauthVersion = "1.0";
        $oauthMethod = "POST";


        $params = array(
            "oauth_callback" => $oauthCallback,
            "oauth_consumer_key" => $oauthConsumerKey,
            "oauth_nonce" => $oauthNonce,
            "oauth_signature_method" => $oauthSignatureMethod,
            "oauth_timestamp" => $oauthTimestamp,
            "oauth_version" => $oauthVersion,
        );
        $data = http_build_query($params);

        $encodedData = $oauthMethod."&".urlencode($endpointUrl)."&".urlencode($data);
        $key = $oauthConsumerSecret."&";
        $signature = hash_hmac("sha1",$encodedData, $key, 1);
        $oauthSignature = base64_encode($signature);

        $header = "Authorization: OAuth realm="$realm",";
        foreach ($params as $key=>$value){
            $header .=  $key.'="'.$value."", ";
        }
        $header .= "oauth_signature="".$oauthSignature.'"';

        $curl = curl_init();

        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
        curl_setopt($curl, CURLOPT_CUSTOMREQUEST, 'POST');
        //curl_setopt($curl, CURLOPT_POST, true);
        curl_setopt($curl, CURLOPT_HTTPHEADER, array($header));
        curl_setopt($curl, CURLOPT_URL, $endpointUrl);

        $response = curl_exec($curl);
        curl_close($curl);

        $response = explode('&',$response);
        $key = explode('=',$response[0]);
        $secret = explode('=',$response[1]);
        $oauthkey = $key[1];
        $oauthsecret = $secret[1];

        //echo $oauthkey.' '.$oauthsecret."n";

        //authorize

        $url = $baseurl.'oauth/authorize?oauth_token='.$oauthkey.'&username='.$username.'&password='.$password;

        $curl = curl_init();
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_HEADER, true);
        curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); // Must be set to true so that PHP follows any "Location:" header
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

        $a = curl_exec($ch); // $a will contain all headers

        $url = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);
        curl_close($ch);

        $url = explode('&',$url);
        $url = explode('=',$url[1]);
        $verifier = $url[1];


        //oauth access
        $endpointUrl = $realm."oauth/token";
        $params2 = array(
            'oauth_consumer_key' => $oauthConsumerKey,
            'oauth_nonce' => uniqid(mt_rand(1, 1000)),
            'oauth_signature_method' => 'HMAC-SHA1',
            'oauth_timestamp' => time(),
            'oauth_version' => '1.0',
            'oauth_token' => $oauthkey,
            'oauth_verifier' => $verifier,
        );

        $method = 'POST';
        // this is the url to get Request Token according to Magento doc
        $url = $endpointUrl;

        // start making the signature
        ksort($params2); // @see Zend_Oauth_Signature_SignatureAbstract::_toByteValueOrderedQueryString() for more accurate sorting, including array params
        $sortedParamsByKeyEncodedForm = array();
        foreach ($params2 as $key => $value) {
            $sortedParamsByKeyEncodedForm[] = rawurlencode($key) . '=' . rawurlencode($value);
        }
        $strParams = implode('&', $sortedParamsByKeyEncodedForm);
        $signatureData = strtoupper($method) // HTTP method (POST/GET/PUT/...)
                . '&'
                . rawurlencode($url) // base resource url - without port & query params & anchors, @see how Zend extracts it in Zend_Oauth_Signature_SignatureAbstract::normaliseBaseSignatureUrl()
                . '&'
                . rawurlencode($strParams);

        $key = rawurlencode($oauthConsumerSecret) . '&' . rawurlencode($oauthsecret);
        $oauthSignature = base64_encode(hash_hmac('SHA1', $signatureData, $key, 1));

        $header = "Authorization: OAuth realm="$realm",";
        foreach ($params2 as $key=>$value){
            $header .=  $key.'="'.$value."", ";
        }
        $header .= "oauth_signature="".$oauthSignature.'"';

        $curl = curl_init();

        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
        curl_setopt($curl, CURLOPT_CUSTOMREQUEST, 'POST');
        //curl_setopt($curl, CURLOPT_POST, true);
        curl_setopt($curl, CURLOPT_HTTPHEADER, array($header));
        curl_setopt($curl, CURLOPT_URL, $endpointUrl);

        $response = curl_exec($curl);
        curl_close($curl);


        $response = explode('&',$response);
        $access_key = explode('=',$response[0]);
        $access_key = $access_key[1];
        $access_secret = explode('=',$response[1]);
        $access_secret = $access_secret[1];


        return $access_key.','.$access_secret;
        //return "success";*/


    }


}