/**
* Copyright (C) 2011 Whisper Systems
*
* 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 org.thoughtcrime.securesms.crypto;
import android.content.Context;
import org.thoughtcrime.securesms.R;
import org.thoughtcrime.securesms.database.MessageRecord;
import org.thoughtcrime.securesms.database.SmsDatabase;
import org.thoughtcrime.securesms.protocol.Prefix;
import org.thoughtcrime.securesms.util.InvalidMessageException;
import java.lang.ref.SoftReference;
import java.util.LinkedHashMap;
public class MessageDisplayHelper {
private static final int MAX_CACHE_SIZE = 2000;
private static final LinkedHashMap> decryptedBodyCache = new LinkedHashMap>() {
@Override
protected boolean removeEldestEntry(Entry> eldest) {
return this.size() > MAX_CACHE_SIZE;
}
};
private static boolean isUnreadableAsymmetricMessage(long type) {
return type == SmsDatabase.Types.FAILED_DECRYPT_TYPE;
}
private static boolean isInProcessAsymmetricMessage(String body, long type) {
return type == SmsDatabase.Types.DECRYPT_IN_PROGRESS_TYPE || (type == 0 && body.startsWith(Prefix.ASYMMETRIC_ENCRYPT)) || (type == 0 && body.startsWith(Prefix.ASYMMETRIC_LOCAL_ENCRYPT));
}
private static boolean isRogueAsymmetricMessage(long type) {
return type == SmsDatabase.Types.NO_SESSION_TYPE;
}
private static boolean isKeyExchange(String body) {
return body.startsWith(Prefix.KEY_EXCHANGE);
}
private static boolean isProcessedKeyExchange(String body) {
return body.startsWith(Prefix.PROCESSED_KEY_EXCHANGE);
}
private static boolean isStaleKeyExchange(String body) {
return body.startsWith(Prefix.STALE_KEY_EXCHANGE);
}
private static String checkCacheForBody(String body) {
if (decryptedBodyCache.containsKey(body)) {
String decryptedBody = decryptedBodyCache.get(body).get();
if (decryptedBody != null) {
return decryptedBody;
} else {
decryptedBodyCache.remove(body);
return null;
}
}
return null;
}
public static void setDecryptedMessageBody(Context context, String body,
MessageRecord message, MasterCipher bodyCipher)
{
try {
if (body.startsWith(Prefix.SYMMETRIC_ENCRYPT)) {
String cacheResult = checkCacheForBody(body);
if (cacheResult != null) {
body = cacheResult;
} else {
String decryptedBody = bodyCipher.decryptBody(body.substring(Prefix.SYMMETRIC_ENCRYPT.length()));
decryptedBodyCache.put(body, new SoftReference(decryptedBody));
body = decryptedBody;
}
}
if (isUnreadableAsymmetricMessage(message.getType())) {
message.setBody(context.getString(R.string.bad_encrypted_message));
message.setEmphasis(true);
} else if (isInProcessAsymmetricMessage(body, message.getType())) {
message.setBody(context.getString(R.string.decrypting_please_wait));
message.setEmphasis(true);
} else if (isRogueAsymmetricMessage(message.getType())) {
message.setBody(context.getString(R.string.message_encrypted_for_non_existing_session));
message.setEmphasis(true);
} else if (isKeyExchange(body)) {
message.setKeyExchange(true);
message.setEmphasis(true);
message.setBody(body);
} else if (isProcessedKeyExchange(body)) {
message.setProcessedKeyExchange(true);
message.setEmphasis(true);
message.setBody(body);
} else if (isStaleKeyExchange(body)) {
message.setStaleKeyExchange(true);
message.setEmphasis(true);
message.setBody(body);
} else {
message.setBody(body);
message.setEmphasis(false);
}
} catch (InvalidMessageException ime) {
message.setBody(context.getString(R.string.decryption_error_local_message_corrupted_mac_doesn_t_match_potential_tampering_question));
message.setEmphasis(true);
}
}
}