src/Consumer.php
public static function getSignature($method)
    {
        switch ($method) {
            case 'HMAC-SHA1':
                return new Signature\HMACSHA1();
                break;

            case 'RSA-SHA1':
                return new Signature\RSASHA1();
                break;

            case 'PLAINTEXT':
                return new Signature\PLAINTEXT();
                break;

            default:
                throw new RuntimeException('Invalid signature method');
                break;
        }
    }
public static function getSignature($method)
    {
        switch ($method) {
            case 'HMAC-SHA1':
                return new Signature\HMACSHA1();
                break;

            case 'RSA-SHA1':
                return new Signature\RSASHA1();
                break;

            case 'PLAINTEXT':
                return new Signature\PLAINTEXT();
                break;

            default:
                throw new RuntimeException('Invalid signature method');
                break;
        }
    }
Returns the signature object based on the $method throws an exception if
the method is not supported

@param string $method
@return \PSX\Oauth\SignatureAbstract