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package org.whispersystems.libaxolotl.protocol;
import com.google.protobuf.ByteString;
import org.whispersystems.libaxolotl.IdentityKey;
import org.whispersystems.libaxolotl.InvalidKeyException;
import org.whispersystems.libaxolotl.InvalidMessageException;
import org.whispersystems.libaxolotl.InvalidVersionException;
import org.whispersystems.libaxolotl.LegacyMessageException;
import org.whispersystems.libaxolotl.ecc.Curve;
import org.whispersystems.libaxolotl.ecc.ECPublicKey;
import org.whispersystems.libaxolotl.util.ByteUtil;
import java.io.IOException;
import static org.whispersystems.libaxolotl.protocol.WhisperProtos.KeyExchangeMessage.Builder;
public class KeyExchangeMessage {
public static final int INITIATE_FLAG = 0x01;
public static final int RESPONSE_FLAG = 0X02;
public static final int SIMULTAENOUS_INITIATE_FLAG = 0x04;
private final int version;
private final int supportedVersion;
private final int sequence;
private final int flags;
private final ECPublicKey baseKey;
private final byte[] baseKeySignature;
private final ECPublicKey ratchetKey;
private final IdentityKey identityKey;
private final byte[] serialized;
public KeyExchangeMessage(int messageVersion, int sequence, int flags,
ECPublicKey baseKey, byte[] baseKeySignature,
ECPublicKey ratchetKey,
IdentityKey identityKey)
{
this.supportedVersion = CiphertextMessage.CURRENT_VERSION;
this.version = messageVersion;
this.sequence = sequence;
this.flags = flags;
this.baseKey = baseKey;
this.baseKeySignature = baseKeySignature;
this.ratchetKey = ratchetKey;
this.identityKey = identityKey;
byte[] version = {ByteUtil.intsToByteHighAndLow(this.version, this.supportedVersion)};
Builder builder = WhisperProtos.KeyExchangeMessage
.newBuilder()
.setId((sequence << 5) | flags)
.setBaseKey(ByteString.copyFrom(baseKey.serialize()))
.setRatchetKey(ByteString.copyFrom(ratchetKey.serialize()))
.setIdentityKey(ByteString.copyFrom(identityKey.serialize()));
if (messageVersion >= 3) {
builder.setBaseKeySignature(ByteString.copyFrom(baseKeySignature));
}
this.serialized = ByteUtil.combine(version, builder.build().toByteArray());
}
public KeyExchangeMessage(byte[] serialized)
throws InvalidMessageException, InvalidVersionException, LegacyMessageException
{
try {
byte[][] parts = ByteUtil.split(serialized, 1, serialized.length - 1);
this.version = ByteUtil.highBitsToInt(parts[0][0]);
this.supportedVersion = ByteUtil.lowBitsToInt(parts[0][0]);
if (this.version <= CiphertextMessage.UNSUPPORTED_VERSION) {
throw new LegacyMessageException("Unsupported legacy version: " + this.version);
}
if (this.version > CiphertextMessage.CURRENT_VERSION) {
throw new InvalidVersionException("Unknown version: " + this.version);
}
WhisperProtos.KeyExchangeMessage message = WhisperProtos.KeyExchangeMessage.parseFrom(parts[1]);
if (!message.hasId() || !message.hasBaseKey() ||
!message.hasRatchetKey() || !message.hasIdentityKey() ||
(this.version >=3 && !message.hasBaseKeySignature()))
{
throw new InvalidMessageException("Some required fields missing!");
}
this.sequence = message.getId() >> 5;
this.flags = message.getId() & 0x1f;
this.serialized = serialized;
this.baseKey = Curve.decodePoint(message.getBaseKey().toByteArray(), 0);
this.baseKeySignature = message.getBaseKeySignature().toByteArray();
this.ratchetKey = Curve.decodePoint(message.getRatchetKey().toByteArray(), 0);
this.identityKey = new IdentityKey(message.getIdentityKey().toByteArray(), 0);
} catch (InvalidKeyException | IOException e) {
throw new InvalidMessageException(e);
}
}
public int getVersion() {
return version;
}
public ECPublicKey getBaseKey() {
return baseKey;
}
public byte[] getBaseKeySignature() {
return baseKeySignature;
}
public ECPublicKey getRatchetKey() {
return ratchetKey;
}
public IdentityKey getIdentityKey() {
return identityKey;
}
public boolean hasIdentityKey() {
return true;
}
public int getMaxVersion() {
return supportedVersion;
}
public boolean isResponse() {
return ((flags & RESPONSE_FLAG) != 0);
}
public boolean isInitiate() {
return (flags & INITIATE_FLAG) != 0;
}
public boolean isResponseForSimultaneousInitiate() {
return (flags & SIMULTAENOUS_INITIATE_FLAG) != 0;
}
public int getFlags() {
return flags;
}
public int getSequence() {
return sequence;
}
public byte[] serialize() {
return serialized;
}
}
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