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Add partial support for operating as a linked device.

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This commit is contained in:
Cody Henthorne
2022-01-11 14:53:21 -05:00
committed by Greyson Parrelli
parent 112f4bb281
commit 7203228626
33 changed files with 569 additions and 109 deletions
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65
app/src/main/java/org/thoughtcrime/securesms/database/loaders/DeviceListLoader.java
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@@ -4,6 +4,7 @@ import android.content.Context;
import android.text.TextUtils;
import androidx.annotation.NonNull;
import androidx.annotation.VisibleForTesting;
import com.annimon.stream.Stream;
@@ -12,6 +13,7 @@ import org.thoughtcrime.securesms.crypto.IdentityKeyUtil;
import org.thoughtcrime.securesms.devicelist.Device;
import org.thoughtcrime.securesms.util.AsyncLoader;
import org.thoughtcrime.securesms.util.Base64;
import org.whispersystems.libsignal.IdentityKeyPair;
import org.whispersystems.libsignal.InvalidKeyException;
import org.whispersystems.libsignal.ecc.Curve;
import org.whispersystems.libsignal.ecc.ECPrivateKey;
@@ -75,35 +77,7 @@ public class DeviceListLoader extends AsyncLoader<List<Device>> {
throw new IOException("Got a DeviceName that wasn't properly populated.");
}
byte[] syntheticIv = deviceName.getSyntheticIv().toByteArray();
byte[] cipherText = deviceName.getCiphertext().toByteArray();
ECPrivateKey identityKey = IdentityKeyUtil.getIdentityKeyPair(getContext()).getPrivateKey();
ECPublicKey ephemeralPublic = Curve.decodePoint(deviceName.getEphemeralPublic().toByteArray(), 0);
byte[] masterSecret = Curve.calculateAgreement(ephemeralPublic, identityKey);
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(new SecretKeySpec(masterSecret, "HmacSHA256"));
byte[] cipherKeyPart1 = mac.doFinal("cipher".getBytes());
mac.init(new SecretKeySpec(cipherKeyPart1, "HmacSHA256"));
byte[] cipherKey = mac.doFinal(syntheticIv);
Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(cipherKey, "AES"), new IvParameterSpec(new byte[16]));
final byte[] plaintext = cipher.doFinal(cipherText);
mac.init(new SecretKeySpec(masterSecret, "HmacSHA256"));
byte[] verificationPart1 = mac.doFinal("auth".getBytes());
mac.init(new SecretKeySpec(verificationPart1, "HmacSHA256"));
byte[] verificationPart2 = mac.doFinal(plaintext);
byte[] ourSyntheticIv = ByteUtil.trim(verificationPart2, 16);
if (!MessageDigest.isEqual(ourSyntheticIv, syntheticIv)) {
throw new GeneralSecurityException("The computed syntheticIv didn't match the actual syntheticIv.");
}
return new Device(deviceInfo.getId(), new String(plaintext), deviceInfo.getCreated(), deviceInfo.getLastSeen());
return new Device(deviceInfo.getId(), new String(decryptName(deviceName, IdentityKeyUtil.getIdentityKeyPair(getContext()))), deviceInfo.getCreated(), deviceInfo.getLastSeen());
} catch (IOException e) {
Log.w(TAG, "Failed while reading the protobuf.", e);
@@ -114,6 +88,39 @@ public class DeviceListLoader extends AsyncLoader<List<Device>> {
return new Device(deviceInfo.getId(), deviceInfo.getName(), deviceInfo.getCreated(), deviceInfo.getLastSeen());
}
@VisibleForTesting
public static byte[] decryptName(DeviceName deviceName, IdentityKeyPair identityKeyPair) throws InvalidKeyException, GeneralSecurityException {
byte[] syntheticIv = deviceName.getSyntheticIv().toByteArray();
byte[] cipherText = deviceName.getCiphertext().toByteArray();
ECPrivateKey identityKey = identityKeyPair.getPrivateKey();
ECPublicKey ephemeralPublic = Curve.decodePoint(deviceName.getEphemeralPublic().toByteArray(), 0);
byte[] masterSecret = Curve.calculateAgreement(ephemeralPublic, identityKey);
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(new SecretKeySpec(masterSecret, "HmacSHA256"));
byte[] cipherKeyPart1 = mac.doFinal("cipher".getBytes());
mac.init(new SecretKeySpec(cipherKeyPart1, "HmacSHA256"));
byte[] cipherKey = mac.doFinal(syntheticIv);
Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(cipherKey, "AES"), new IvParameterSpec(new byte[16]));
final byte[] plaintext = cipher.doFinal(cipherText);
mac.init(new SecretKeySpec(masterSecret, "HmacSHA256"));
byte[] verificationPart1 = mac.doFinal("auth".getBytes());
mac.init(new SecretKeySpec(verificationPart1, "HmacSHA256"));
byte[] verificationPart2 = mac.doFinal(plaintext);
byte[] ourSyntheticIv = ByteUtil.trim(verificationPart2, 16);
if (!MessageDigest.isEqual(ourSyntheticIv, syntheticIv)) {
throw new GeneralSecurityException("The computed syntheticIv didn't match the actual syntheticIv.");
}
return plaintext;
}
private static class DeviceComparator implements Comparator<Device> {
@Override