src/main/java/org/imsglobal/lti/BasicLTIUtil.java
public static boolean checkProperties(
            Map<String, String> postProp, String url, String method,
            String oauth_consumer_key, String oauth_consumer_secret) {

        OAuthMessage oam = new OAuthMessage(method, url, postProp.entrySet());
        OAuthConsumer cons = new OAuthConsumer("about:blank", oauth_consumer_key,
                oauth_consumer_secret, null);
        OAuthValidator oav = new SimpleOAuthValidator();

        OAuthAccessor acc = new OAuthAccessor(cons);

        String base_string = null;
        try {
            base_string = OAuthSignatureMethod.getBaseString(oam);
        } catch (Exception e) {
            M_log.warning(e.getLocalizedMessage());
            base_string = null;
            return false;
        }

        try {
            oav.validateMessage(oam, acc);
        } catch (Exception e) {
            M_log.warning("Provider failed to validate message");
            M_log.warning(e.getLocalizedMessage());
            if (base_string != null) {
                M_log.warning(base_string);
            }
            return false;
        }
        return true;
    }
public static boolean checkProperties(
            Map<String, String> postProp, String url, String method,
            String oauth_consumer_key, String oauth_consumer_secret) {

        OAuthMessage oam = new OAuthMessage(method, url, postProp.entrySet());
        OAuthConsumer cons = new OAuthConsumer("about:blank", oauth_consumer_key,
                oauth_consumer_secret, null);
        OAuthValidator oav = new SimpleOAuthValidator();

        OAuthAccessor acc = new OAuthAccessor(cons);

        String base_string = null;
        try {
            base_string = OAuthSignatureMethod.getBaseString(oam);
        } catch (Exception e) {
            M_log.warning(e.getLocalizedMessage());
            base_string = null;
            return false;
        }

        try {
            oav.validateMessage(oam, acc);
        } catch (Exception e) {
            M_log.warning("Provider failed to validate message");
            M_log.warning(e.getLocalizedMessage());
            if (base_string != null) {
                M_log.warning(base_string);
            }
            return false;
        }
        return true;
    }
Check if the fields are properly signed

@param postProp
@param url
@param method
@param oauth_consumer_key
@param oauth_consumer_secret

@return