diff --git a/jni/libzrtp/src/libzrtpcpp/ZrtpUserCallback.h b/jni/libzrtp/src/libzrtpcpp/ZrtpUserCallback.h
new file mode 100644
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+/*
+  Copyright (C) 2006-2008 Werner Dittmann
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _ZRTPUSERCALLBACK_H_
+#define _ZRTPUSERCALLBACK_H_
+
+/**
+ * @file ZrtpUserCallback.h
+ * @brief The ZRTP UserCallback class
+ *
+ * @ingroup GNU_ZRTP
+ * @{
+ */
+
+#include <stdint.h>
+#include <string>
+
+#include <libzrtpcpp/ZrtpCodes.h>
+
+/**
+ * Application callback methods.
+ *
+ * The ccRTP specific part of GNU ZRTP uses these callback methods
+ * to report ZRTP events to the application. This class implements a
+ * default behaviour for each callback method, usually just a return.
+ *
+ * An application may extend this class and overload methods
+ * to implement its own behaviour. The application must register its
+ * callback class using ZrtpQueue#setUserCallback().
+ *
+ * <b>CAVEAT</b><br/>
+ * All methods of the user callback class and classes that
+ * extend this class run in the context of the RTP thread. Thus it is
+ * of paramount importance to keep the execution time of the methods
+ * as short as possible.
+ *
+ * @author Werner Dittmann <Werner.Dittmann@t-online.de>
+ */
+
+class __EXPORT ZrtpUserCallback {
+
+    public:
+
+        /// Create the stadard user callback class.
+        ZrtpUserCallback() {}
+
+        virtual ~ZrtpUserCallback() {};
+
+        /**
+         * Inform user interface that security is active now.
+         *
+         * ZRTP calls this method if the sender and the receiver are
+         * in secure mode now.
+         *
+         * @param cipher
+         *    Name and mode of cipher used to encrypt the SRTP stream
+         */
+        virtual void secureOn(std::string cipher) {
+            return;
+        }
+        /**
+         * Inform user interface that security is not active any more.
+         *
+         * ZRTP calls this method if either the sender or the receiver
+         * left secure mode.
+         *
+         */
+        virtual void secureOff() {
+            return;
+        }
+
+        /**
+         * Show the Short Authentication String (SAS) on user interface.
+         *
+         * ZRTP calls this method to display the SAS and inform about the SAS
+         * verification status. The user interface shall enable a SAS verfication
+         * button (or similar UI element). The user shall click on this UI
+         * element after he/she confirmed the SAS code with the partner.
+         *
+         * @param sas
+         *     The string containing the SAS.
+         * @param verified
+         *    If <code>verified</code> is true then SAS was verified by both
+         *    parties during a previous call, otherwise it is set to false.
+         */
+        virtual void showSAS(std::string sas, bool verified) {
+            return;
+        }
+
+        /**
+         * Inform the user that ZRTP received "go clear" message from its peer.
+         *
+         * On receipt of a go clear message the user is requested to confirm
+         * a switch to unsecure (clear) modus. Until the user confirms ZRTP
+         * (and the underlying RTP) does not send any data.
+         */
+        virtual void confirmGoClear() {
+            return;
+        }
+
+        /**
+         * Show some information to user.
+         *
+         * ZRTP calls this method to display some information to the user.
+         * Along with the message ZRTP provides a severity indicator that
+         * defines: Info, Warning, Error, and Alert. Refer to the <code>
+         * MessageSeverity</code> enum in <code>ZrtpCodes.h</code>. The
+         * UI may use this indicator to highlight messages or alike.
+         *
+         * @param sev
+         *     Severity of the message.
+         * @param subCode
+         *     The subcode identifying the reason.
+         */
+        virtual void showMessage(GnuZrtpCodes::MessageSeverity sev, int32_t subCode) {
+            return;
+        }
+
+        /**
+         * ZRTPQueue calls this if the negotiation failed.
+         *
+         * ZRTPQueue calls this method in case ZRTP negotiation failed. The
+         * parameters show the severity as well as some explanatory text.
+         * Refer to the <code>MessageSeverity</code> enum above.
+         *
+         * @param severity
+         *     This defines the message's severity
+         * @param subCode
+         *     The subcode identifying the reason.
+         */
+        virtual void zrtpNegotiationFailed(GnuZrtpCodes::MessageSeverity severity,
+                                           int32_t subCode) {
+            return;
+        }
+
+        /**
+         * ZRTPQueue calls this method if the other side does not support ZRTP.
+         *
+         * If the other side does not answer the ZRTP <em>Hello</em> packets then
+         * ZRTP calls this method.
+         *
+         */
+        virtual void zrtpNotSuppOther() {
+            return;
+        }
+
+        /**
+         * ZRTPQueue calls this method to inform about a PBX enrollment request.
+         *
+         * Please refer to chapter 8.3 ff to get more details about PBX enrollment
+         * and SAS relay.
+         *
+         * @param info
+         *    Give some information to the user about the PBX requesting an
+         *    enrollment.
+         *
+         */
+        virtual void zrtpAskEnrollment(GnuZrtpCodes::InfoEnrollment info) {
+            return;
+        }
+
+        /**
+         * ZRTPQueue calls this method to inform about PBX enrollment result.
+         *
+         * Informs the use about the acceptance or denial of an PBX enrollment
+         * request
+         *
+         * @param info
+         *    Give some information to the user about the result of an
+         *    enrollment.
+         *
+         */
+        virtual void zrtpInformEnrollment(GnuZrtpCodes::InfoEnrollment info) {
+            return;
+        }
+
+        /**
+         * ZRTPQueue calls this method to request a SAS signature.
+         *
+         * After ZRTP core was able to compute the Short Authentication String
+         * (SAS) it calls this method. The client may now use an approriate
+         * method to sign the SAS. The client may use
+         * setSignatureData() of ZrtpQueue to store the signature
+         * data an enable signature transmission to the other peer. Refer
+         * to chapter 8.2 of ZRTP specification.
+         *
+         * @param sasHash
+         *    Pointer to the 32 byte SAS hash to be signed.
+         * @see ZrtpQueue#setSignatureData
+         *
+         */
+        virtual void signSAS(uint8_t* sasHash) {
+            return;
+        }
+
+        /**
+         * ZRTPQueue calls this method to request a SAS signature check.
+         *
+         * After ZRTP received a SAS signature in one of the Confirm packets it
+         * call this method. The client may use <code>getSignatureLength()</code>
+         * and <code>getSignatureData()</code>of ZrtpQueue to get the signature
+         * data and perform the signature check. Refer to chapter 8.2 of ZRTP
+         * specification.
+         *
+         * If the signature check fails the client may return false to ZRTP. In
+         * this case ZRTP signals an error to the other peer and terminates
+         * the ZRTP handshake.
+         *
+         * @param sasHash
+         *    Pointer to the 32 byte SAS hash that was signed by the other peer.
+         * @return
+         *    true if the signature was ok, false otherwise.
+         *
+         */
+        virtual bool checkSASSignature(uint8_t* sasHash) {
+            return true;
+        }
+};
+
+#endif