chamilo-lms2/plugin/ims_lti/vendor/oauth1/code/OAuthSignatureMethod_HMAC_SHA1.php

<?php

/**
 * The HMAC-SHA1 signature method uses the HMAC-SHA1 signature algorithm as
 * defined in [RFC2104] where the Signature Base String is the text and the
 * key is the concatenated values (each first encoded per Parameter Encoding)
 * of the Consumer Secret and Token Secret, separated by an '&' character
 * (ASCII code 38) even if empty.
 * - Chapter 9.2 ("HMAC-SHA1")
 */
class OAuthSignatureMethod_HMAC_SHA1 extends OAuthSignatureMethod {
  function get_name() {
    return "HMAC-SHA1";
  }

  public function build_signature($request, $consumer, $token) {
    $base_string = $request->get_signature_base_string();
    $request->base_string = $base_string;

    $key_parts = array(
      $consumer->secret,
      ($token) ? $token->secret :  ""
    );

    $key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
    $key = implode('&', $key_parts);

    return base64_encode(hash_hmac('sha1', $base_string, $key, true));
  }
}