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ZRTP for Java library, Jitsi fork without embedded ciphers
/*
* 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
*/
package gnu.java.zrtp.packets;
import gnu.java.zrtp.ZrtpConstants;
import gnu.java.zrtp.utils.ZrtpUtils;
import org.bouncycastle.math.ec.custom.djb.Curve25519;
/**
* @author Werner Dittmann <[email protected]>
*
*/
public class ZrtpPacketDHPart extends ZrtpPacketBase {
private int dhLength; // length of DH data (3k or 4k)
/*
* Now the DHPart packet specific offsets into the packet buffer. They
* all start after ZRTP_HEADER_LENGTH and a given in bytes, not ZRTP
* words.
*/
private static final int HASH_H1_OFFSET = ZRTP_HEADER_LENGTH * ZRTP_WORD_SIZE; // [8*ZRTP_WORD_SIZE];
private static final int RS1ID_OFFSET = HASH_H1_OFFSET + HASH_IMAGE_SIZE; // [2*ZRTP_WORD_SIZE];
private static final int RS2ID_OFFSET = RS1ID_OFFSET + 2*ZRTP_WORD_SIZE; // [2*ZRTP_WORD_SIZE];
// private static final int SIGS_ID_OFFSET = RS2ID_OFFSET + 2*ZRTP_WORD_SIZE; // [2*ZRTP_WORD_SIZE];
private static final int S3_ID_OFFSET = RS2ID_OFFSET + 2*ZRTP_WORD_SIZE; // [2*ZRTP_WORD_SIZE];
private static final int PBX_SECRET_ID_OFFSET = S3_ID_OFFSET + 2*ZRTP_WORD_SIZE;// [2*ZRTP_WORD_SIZE];
private static final int PUBLIC_KEY_OFFSET = PBX_SECRET_ID_OFFSET + 2*ZRTP_WORD_SIZE;
/*
* The number of the fixed DHPacket specific ZRTP fields in words
*/
private static final int ZRTP_DHPART_FIXED_LENGTH = 16;
// required bytes to hold the header, the fix part and the CRC
private static final int DHPART_FIXED_LENGTH =
(ZRTP_HEADER_LENGTH + ZRTP_DHPART_FIXED_LENGTH) * ZRTP_WORD_SIZE + CRC_SIZE;
/**
* Constructor for a new DHPart message
*
*/
public ZrtpPacketDHPart() {
super(null);
}
/**
* Constructor for a new DHPart message with DH part type.
*
* @param pkt type of DH key agreement to use
*/
@SuppressWarnings("unused")
public ZrtpPacketDHPart(final ZrtpConstants.SupportedPubKeys pkt) {
super(null);
setPubKeyType(pkt);
}
/**
* Constructor for DHPart message initialized with received data.
*
* @param data received from the network.
*/
public ZrtpPacketDHPart(final byte[] data) {
super(data);
short len = getLength();
if (len == 85) {
dhLength = 256;
}
else if (len == 117) {
dhLength = 384;
}
else if (len == 37) {
dhLength = 64;
}
else if (len == 45) {
dhLength = 96;
}
else if (len == 29) { // E255
dhLength = 32;
}
else {
dhLength = 0;
}
}
public void setPubKeyType(final ZrtpConstants.SupportedPubKeys pkt) {
if (pkt == ZrtpConstants.SupportedPubKeys.DH2K) {
dhLength = 256;
}
else if (pkt == ZrtpConstants.SupportedPubKeys.DH3K) {
dhLength = 384;
}
else if (pkt == ZrtpConstants.SupportedPubKeys.EC25) {
dhLength = 64;
}
else if (pkt == ZrtpConstants.SupportedPubKeys.EC38) {
dhLength = 96;
}
else if (pkt == ZrtpConstants.SupportedPubKeys.E255) {
dhLength = 32; //or new Curve25519().getBitLength()/8
}
else
return;
// compute total length of ZRTP message including space for CRC
int length = DHPART_FIXED_LENGTH + dhLength + (2 * ZRTP_WORD_SIZE); // HMAC field is 2*ZRTP_WORD_SIZE
// allocate buffer
packetBuffer = new byte[length];
// Message length does not include CRC
setLength((length-CRC_SIZE) / ZRTP_WORD_SIZE);
setZrtpId();
}
public final byte[] getPv() {
return ZrtpUtils.readRegion(packetBuffer, PUBLIC_KEY_OFFSET, dhLength);
}
public final byte[] getRs1Id() {
return ZrtpUtils.readRegion(packetBuffer, RS1ID_OFFSET, 2*ZRTP_WORD_SIZE);
}
public final byte[] getRs2Id() {
return ZrtpUtils.readRegion(packetBuffer, RS2ID_OFFSET, 2*ZRTP_WORD_SIZE);
}
public final byte[] getAuxSecretId() {
return ZrtpUtils.readRegion(packetBuffer, S3_ID_OFFSET, 2*ZRTP_WORD_SIZE);
}
public final byte[] getPbxSecretId() {
return ZrtpUtils.readRegion(packetBuffer, PBX_SECRET_ID_OFFSET, 2*ZRTP_WORD_SIZE);
}
public final byte[] getH1() {
return ZrtpUtils.readRegion(packetBuffer, HASH_H1_OFFSET, HASH_IMAGE_SIZE);
}
public final byte[] getHMAC() {
return ZrtpUtils.readRegion(packetBuffer, PUBLIC_KEY_OFFSET+dhLength, 2*ZRTP_WORD_SIZE);
}
/// Check if packet length makes sense. Smallest DHpart packet is 29 words, using DH E255
public final boolean isLengthOk() {
return getLength() >= 29;
}
/**
* Setter methods.
*
*/
public final void setPv(final byte[] data) {
System.arraycopy(data, 0, packetBuffer, PUBLIC_KEY_OFFSET, dhLength);
}
public final void setRs1Id(final byte[] data) {
System.arraycopy(data, 0, packetBuffer, RS1ID_OFFSET, 2*ZRTP_WORD_SIZE);
}
public final void setRs2Id(final byte[] data) {
System.arraycopy(data, 0, packetBuffer, RS2ID_OFFSET, 2*ZRTP_WORD_SIZE);
}
public final void setAuxSecretId(final byte[] data) {
System.arraycopy(data, 0, packetBuffer, S3_ID_OFFSET, 2*ZRTP_WORD_SIZE);
}
public final void setPbxSecretId(final byte[] data) {
System.arraycopy(data, 0, packetBuffer, PBX_SECRET_ID_OFFSET, 2*ZRTP_WORD_SIZE);
}
public final void setH1(final byte[] data) {
System.arraycopy(data, 0, packetBuffer, HASH_H1_OFFSET, HASH_IMAGE_SIZE);
}
public final void setHMAC(final byte[] data) {
System.arraycopy(data, 0, packetBuffer, PUBLIC_KEY_OFFSET+dhLength, 2*ZRTP_WORD_SIZE);
}
/* ***
public static void main(String[] args) {
ZrtpPacketDHPart pkt = new ZrtpPacketDHPart(ZrtpConstants.SupportedPubKeys.DH3K);
System.err.println("DHPart length: " + pkt.getLength());
pkt.setMessageType(ZrtpConstants.DHPart1Msg);
System.err.println("packetBuffer length in bytes: " + pkt.getHeaderBase().length);
ZrtpUtils.hexdump("DHPart packet", pkt.getHeaderBase(), pkt.getHeaderBase().length);
}
*** */
}