GroupId for GV2.

app/src/main/java/org/thoughtcrime/securesms/database/GroupDatabase.java

@@ -26,7 +26,6 @@ import org.whispersystems.signalservice.api.messages.SignalServiceAttachmentPoin
 
 import java.io.Closeable;
 import java.security.SecureRandom;
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
@@ -233,7 +232,7 @@ public class GroupDatabase extends Database {
     contentValues.put(AVATAR_RELAY, relay);
     contentValues.put(TIMESTAMP, System.currentTimeMillis());
     contentValues.put(ACTIVE, 1);
-    contentValues.put(MMS, groupId.isMmsGroup());
+    contentValues.put(MMS, groupId.isMms());
 
     databaseHelper.getWritableDatabase().insert(TABLE_NAME, null, contentValues);
 

app/src/main/java/org/thoughtcrime/securesms/database/RecipientDatabase.java

@@ -356,7 +356,7 @@ public class RecipientDatabase extends Database {
     if (result.neededInsert) {
       ContentValues values = new ContentValues();
 
-      if (groupId.isMmsGroup()) {
+      if (groupId.isMms()) {
         values.put(GROUP_TYPE, GroupType.MMS.getId());
       } else {
         values.put(GROUP_TYPE, GroupType.SIGNAL_V1.getId());
@@ -1406,9 +1406,9 @@ public class RecipientDatabase extends Database {
         db.update(TABLE_NAME, setBlocked, UUID + " = ?", new String[] { uuid });
       }
 
-      List<GroupId> groupIdStrings = Stream.of(groupIds).map(GroupId::v1).toList();
+      List<GroupId.V1> groupIdStrings = Stream.of(groupIds).map(GroupId::v1).toList();
 
-      for (GroupId groupId : groupIdStrings) {
+      for (GroupId.V1 groupId : groupIdStrings) {
         db.update(TABLE_NAME, setBlocked, GROUP_ID + " = ?", new String[] { groupId.toString() });
       }
 

app/src/main/java/org/thoughtcrime/securesms/groups/GroupId.java

@@ -3,27 +3,52 @@ package org.thoughtcrime.securesms.groups;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import org.signal.zkgroup.groups.GroupIdentifier;
+import org.signal.zkgroup.groups.GroupMasterKey;
+import org.signal.zkgroup.groups.GroupSecretParams;
 import org.thoughtcrime.securesms.util.Hex;
 
 import java.io.IOException;
 
-public final class GroupId {
+public abstract class GroupId {
 
   private static final String ENCODED_SIGNAL_GROUP_PREFIX = "__textsecure_group__!";
   private static final String ENCODED_MMS_GROUP_PREFIX    = "__signal_mms_group__!";
+  private static final int    V2_BYTE_LENGTH              = GroupIdentifier.SIZE;
+  private static final int    V2_ENCODED_LENGTH           = ENCODED_SIGNAL_GROUP_PREFIX.length() + V2_BYTE_LENGTH * 2;
 
   private final String encodedId;
 
-  private GroupId(@NonNull String encodedId) {
+  private GroupId(@NonNull String prefix, @NonNull byte[] bytes) {
-    this.encodedId = encodedId;
+    this.encodedId = prefix + Hex.toStringCondensed(bytes);
   }
 
-  public static @NonNull GroupId v1(byte[] gv1GroupIdBytes) {
+  public static @NonNull GroupId.Mms mms(byte[] mmsGroupIdBytes) {
-    return new GroupId(ENCODED_SIGNAL_GROUP_PREFIX + Hex.toStringCondensed(gv1GroupIdBytes));
+    return new GroupId.Mms(mmsGroupIdBytes);
   }
 
-  public static @NonNull GroupId mms(byte[] mmsGroupIdBytes) {
+  public static @NonNull GroupId.V1 v1(byte[] gv1GroupIdBytes) {
-    return new GroupId(ENCODED_MMS_GROUP_PREFIX + Hex.toStringCondensed(mmsGroupIdBytes));
+    if (gv1GroupIdBytes.length == V2_BYTE_LENGTH) {
+      throw new AssertionError();
+    }
+    return new GroupId.V1(gv1GroupIdBytes);
+  }
+
+  public static GroupId.V2 v2(@NonNull byte[] bytes) {
+    if (bytes.length != V2_BYTE_LENGTH) {
+      throw new AssertionError();
+    }
+    return new GroupId.V2(bytes);
+  }
+
+  public static GroupId.V2 v2(@NonNull GroupIdentifier groupIdentifier) {
+    return v2(groupIdentifier.serialize());
+  }
+
+  public static GroupId.V2 v2(@NonNull GroupMasterKey masterKey) {
+    return v2(GroupSecretParams.deriveFromMasterKey(masterKey)
+                               .getPublicParams()
+                               .getGroupIdentifier());
   }
 
   public static @NonNull GroupId parse(@NonNull String encodedGroupId) {
@@ -33,7 +58,11 @@ public final class GroupId {
       }
 
       byte[] bytes = extractDecodedId(encodedGroupId);
-      return isMmsGroup(encodedGroupId) ? mms(bytes) : v1(bytes);
+
+           if (encodedGroupId.startsWith(ENCODED_MMS_GROUP_PREFIX)) return mms(bytes);
+      else if (encodedGroupId.length() == V2_ENCODED_LENGTH)        return v2(bytes);
+      else                                                          return v1(bytes);
+
     } catch (IOException e) {
       throw new AssertionError(e);
     }
@@ -55,10 +84,6 @@ public final class GroupId {
     return Hex.fromStringCondensed(encodedGroupId.split("!", 2)[1]);
   }
 
-  private static boolean isMmsGroup(@NonNull String groupId) {
-    return groupId.startsWith(ENCODED_MMS_GROUP_PREFIX);
-  }
-
   public byte[] getDecodedId() {
     try {
       return extractDecodedId(encodedId);
@@ -67,10 +92,6 @@ public final class GroupId {
     }
   }
 
-  public boolean isMmsGroup() {
-    return isMmsGroup(encodedId);
-  }
-
   @Override
   public boolean equals(@Nullable Object obj) {
     if (obj instanceof GroupId) {
@@ -90,4 +111,109 @@ public final class GroupId {
   public String toString() {
     return encodedId;
   }
+
+  public abstract boolean isMms();
+
+  public abstract boolean isV1();
+
+  public abstract boolean isV2();
+
+  public abstract boolean isPush();
+
+  public GroupId.Mms requireMms() {
+    if (this instanceof GroupId.Mms) return (GroupId.Mms) this;
+    throw new AssertionError();
+  }
+
+  public GroupId.V1 requireV1() {
+    if (this instanceof GroupId.V1) return (GroupId.V1) this;
+    throw new AssertionError();
+  }
+
+  public GroupId.V2 requireV2() {
+    if (this instanceof GroupId.V2) return (GroupId.V2) this;
+    throw new AssertionError();
+  }
+
+  public GroupId.Push requirePush() {
+    if (this instanceof GroupId.Push) return (GroupId.Push) this;
+    throw new AssertionError();
+  }
+
+  public static final class Mms extends GroupId {
+
+    private Mms(@NonNull byte[] bytes) {
+      super(ENCODED_MMS_GROUP_PREFIX, bytes);
+    }
+
+    @Override
+    public boolean isMms() {
+      return true;
+    }
+
+    @Override
+    public boolean isV1() {
+      return false;
+    }
+
+    @Override
+    public boolean isV2() {
+      return false;
+    }
+
+    @Override
+    public boolean isPush() {
+      return false;
+    }
+  }
+
+  public static abstract class Push extends GroupId {
+    private Push(@NonNull byte[] bytes) {
+      super(ENCODED_SIGNAL_GROUP_PREFIX, bytes);
+    }
+
+    @Override
+    public boolean isMms() {
+      return false;
+    }
+
+    @Override
+    public boolean isPush() {
+      return true;
+    }
+  }
+
+  public static final class V1 extends GroupId.Push {
+
+    private V1(@NonNull byte[] bytes) {
+      super(bytes);
+    }
+
+    @Override
+    public boolean isV1() {
+    return true;
+  }
+
+    @Override
+    public boolean isV2() {
+    return false;
+  }
+  }
+
+  public static final class V2 extends GroupId.Push {
+
+    private V2(@NonNull byte[] bytes) {
+      super(bytes);
+    }
+
+    @Override
+    public boolean isV1() {
+      return false;
+    }
+
+    @Override
+    public boolean isV2() {
+      return true;
+    }
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/groups/GroupManager.java

@@ -53,7 +53,7 @@ public final class GroupManager {
   public static boolean leaveGroup(@NonNull Context context, @NonNull Recipient groupRecipient) {
     GroupId groupId = groupRecipient.requireGroupId();
     
-    return V1GroupManager.leaveGroup(context, groupId, groupRecipient);
+    return V1GroupManager.leaveGroup(context, groupId.requireV1(), groupRecipient);
   }
 
   public static class GroupActionResult {

app/src/main/java/org/thoughtcrime/securesms/groups/V1GroupManager.java

@@ -68,7 +68,7 @@ final class V1GroupManager {
       }
       groupDatabase.onAvatarUpdated(groupId, avatarBytes != null);
       DatabaseFactory.getRecipientDatabase(context).setProfileSharing(groupRecipient.getId(), true);
-      return sendGroupUpdate(context, groupId, memberIds, name, avatarBytes);
+      return sendGroupUpdate(context, groupId.requireV1(), memberIds, name, avatarBytes);
     } else {
       long threadId = DatabaseFactory.getThreadDatabase(context).getThreadIdFor(groupRecipient, ThreadDatabase.DistributionTypes.CONVERSATION);
       return new GroupActionResult(groupRecipient, threadId);
@@ -91,13 +91,13 @@ final class V1GroupManager {
     groupDatabase.updateTitle(groupId, name);
     groupDatabase.onAvatarUpdated(groupId, avatarBytes != null);
 
-    if (!groupId.isMmsGroup()) {
+    if (groupId.isPush()) {
       try {
         AvatarHelper.setAvatar(context, groupRecipientId, avatarBytes != null ? new ByteArrayInputStream(avatarBytes) : null);
       } catch (IOException e) {
         Log.w(TAG, "Failed to save avatar!", e);
       }
-      return sendGroupUpdate(context, groupId, memberAddresses, name, avatarBytes);
+      return sendGroupUpdate(context, groupId.requireV1(), memberAddresses, name, avatarBytes);
     } else {
       Recipient   groupRecipient   = Recipient.resolved(groupRecipientId);
       long        threadId         = DatabaseFactory.getThreadDatabase(context).getThreadIdFor(groupRecipient);
@@ -106,7 +106,7 @@ final class V1GroupManager {
   }
 
   private static GroupActionResult sendGroupUpdate(@NonNull  Context          context,
-                                                   @NonNull  GroupId          groupId,
+                                                   @NonNull  GroupId.V1       groupId,
                                                    @NonNull  Set<RecipientId> members,
                                                    @Nullable String           groupName,
                                                    @Nullable byte[]           avatar)
@@ -143,7 +143,7 @@ final class V1GroupManager {
   }
 
   @WorkerThread
-  static boolean leaveGroup(@NonNull Context context, @NonNull GroupId groupId, @NonNull Recipient groupRecipient) {
+  static boolean leaveGroup(@NonNull Context context, @NonNull GroupId.V1 groupId, @NonNull Recipient groupRecipient) {
     long                                threadId     = DatabaseFactory.getThreadDatabase(context).getThreadIdFor(groupRecipient);
     Optional<OutgoingGroupMediaMessage> leaveMessage = GroupUtil.createGroupLeaveMessage(context, groupRecipient);
 

app/src/main/java/org/thoughtcrime/securesms/jobs/LeaveGroupJob.java

@@ -51,7 +51,7 @@ public class LeaveGroupJob extends BaseJob {
   private static final String KEY_MEMBERS    = "members";
   private static final String KEY_RECIPIENTS = "recipients";
 
-  private final GroupId           groupId;
+  private final GroupId.Push      groupId;
   private final String            name;
   private final List<RecipientId> members;
   private final List<RecipientId> recipients;
@@ -60,7 +60,7 @@ public class LeaveGroupJob extends BaseJob {
     List<RecipientId> members = Stream.of(group.resolve().getParticipants()).map(Recipient::getId).toList();
     members.remove(Recipient.self().getId());
 
-    return new LeaveGroupJob(group.getGroupId().get(),
+    return new LeaveGroupJob(group.getGroupId().get().requirePush(),
                              group.resolve().getDisplayName(ApplicationDependencies.getApplication()),
                              members,
                              members,
@@ -72,7 +72,7 @@ public class LeaveGroupJob extends BaseJob {
                                            .build());
   }
 
-  private LeaveGroupJob(@NonNull GroupId groupId,
+  private LeaveGroupJob(@NonNull GroupId.Push groupId,
                         @NonNull String name,
                         @NonNull List<RecipientId> members,
                         @NonNull List<RecipientId> recipients,

app/src/main/java/org/thoughtcrime/securesms/recipients/LiveRecipient.java

@@ -197,7 +197,7 @@ public final class LiveRecipient {
       List<Recipient> members  = Stream.of(groupRecord.get().getMembers()).filterNot(RecipientId::isUnknown).map(this::fetchRecipientFromDisk).toList();
       Optional<Long>  avatarId = Optional.absent();
 
-      if (settings.getGroupId() != null && !settings.getGroupId().isMmsGroup() && title == null) {
+      if (settings.getGroupId() != null && settings.getGroupId().isPush() && title == null) {
         title = unnamedGroupName;
       }
 

app/src/main/java/org/thoughtcrime/securesms/recipients/Recipient.java

@@ -381,7 +381,7 @@ public class Recipient {
   }
 
   public @Nullable String getName(@NonNull Context context) {
-    if (this.name == null && groupId != null && groupId.isMmsGroup()) {
+    if (this.name == null && groupId != null && groupId.isMms()) {
       List<String> names = new LinkedList<>();
 
       for (Recipient recipient : participants) {
@@ -567,12 +567,12 @@ public class Recipient {
 
   public boolean isMmsGroup() {
     GroupId groupId = resolve().groupId;
-    return groupId != null && groupId.isMmsGroup();
+    return groupId != null && groupId.isMms();
   }
 
   public boolean isPushGroup() {
     GroupId groupId = resolve().groupId;
-    return groupId != null && !groupId.isMmsGroup();
+    return groupId != null && groupId.isPush();
   }
 
   public @NonNull List<Recipient> getParticipants() {

app/src/test/java/org/thoughtcrime/securesms/groups/GroupIdTest.java

@@ -1,6 +1,12 @@
 package org.thoughtcrime.securesms.groups;
 
 import org.junit.Test;
+import org.signal.zkgroup.InvalidInputException;
+import org.signal.zkgroup.groups.GroupIdentifier;
+import org.signal.zkgroup.groups.GroupMasterKey;
+import org.thoughtcrime.securesms.util.Hex;
+
+import java.io.IOException;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
@@ -8,42 +14,89 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotSame;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
+import static org.thoughtcrime.securesms.groups.ZkGroupLibraryUtil.assumeZkGroupSupportedOnOS;
 
 public final class GroupIdTest {
 
   @Test
   public void can_create_for_gv1() {
-    GroupId groupId = GroupId.v1(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 });
+    GroupId.V1 groupId = GroupId.v1(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
 
-    assertEquals("__textsecure_group__!0001020305060708090b0c0d0e0f", groupId.toString());
+    assertEquals("__textsecure_group__!000102030405060708090a0b0c0d0e0f", groupId.toString());
-    assertFalse(groupId.isMmsGroup());
+    assertFalse(groupId.isMms());
   }
 
   @Test
   public void can_parse_gv1() {
-    GroupId groupId = GroupId.parse("__textsecure_group__!0001020305060708090b0c0d0e0f");
+    GroupId groupId = GroupId.parse("__textsecure_group__!000102030405060708090a0b0c0d0e0f");
 
-    assertEquals("__textsecure_group__!0001020305060708090b0c0d0e0f", groupId.toString());
+    assertEquals("__textsecure_group__!000102030405060708090a0b0c0d0e0f", groupId.toString());
-    assertArrayEquals(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 }, groupId.getDecodedId());
+    assertArrayEquals(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }, groupId.getDecodedId());
-    assertFalse(groupId.isMmsGroup());
+    assertFalse(groupId.isMms());
+    assertTrue(groupId.isV1());
+    assertFalse(groupId.isV2());
+    assertTrue(groupId.isPush());
+  }
+
+  @Test
+  public void can_create_for_gv2_from_GroupIdentifier() throws IOException, InvalidInputException {
+    GroupId.V2 groupId = GroupId.v2(new GroupIdentifier(Hex.fromStringCondensed("0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef")));
+
+    assertEquals("__textsecure_group__!0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef", groupId.toString());
+    assertFalse(groupId.isMms());
+    assertFalse(groupId.isV1());
+    assertTrue(groupId.isV2());
+    assertTrue(groupId.isPush());
+  }
+
+  @Test
+  public void can_create_for_gv2_from_GroupMasterKey() throws IOException, InvalidInputException {
+    assumeZkGroupSupportedOnOS();
+
+    GroupId.V2 groupId = GroupId.v2(new GroupMasterKey(Hex.fromStringCondensed("0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef")));
+
+    assertEquals("__textsecure_group__!9f475f59b2518bff6df22e820803f0e3585bd99e686fa7e7fbfc2f92fd5d953e", groupId.toString());
+    assertFalse(groupId.isMms());
+    assertFalse(groupId.isV1());
+    assertTrue(groupId.isV2());
+    assertTrue(groupId.isPush());
+  }
+
+  @Test
+  public void can_parse_gv2() throws IOException {
+    GroupId groupId = GroupId.parse("__textsecure_group__!9f475f59b2518bff6df22e820803f0e3585bd99e686fa7e7fbfc2f92fd5d953e");
+
+    assertEquals("__textsecure_group__!9f475f59b2518bff6df22e820803f0e3585bd99e686fa7e7fbfc2f92fd5d953e", groupId.toString());
+    assertArrayEquals(Hex.fromStringCondensed("9f475f59b2518bff6df22e820803f0e3585bd99e686fa7e7fbfc2f92fd5d953e"), groupId.getDecodedId());
+    assertFalse(groupId.isMms());
+    assertFalse(groupId.isV1());
+    assertTrue(groupId.isV2());
+    assertTrue(groupId.isPush());
   }
 
   @Test
   public void can_create_for_mms() {
-    GroupId groupId = GroupId.mms(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 });
+    GroupId.Mms groupId = GroupId.mms(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
 
-    assertEquals("__signal_mms_group__!0001020305060708090b0c0d0e0f", groupId.toString());
+    assertEquals("__signal_mms_group__!000102030405060708090a0b0c0d0e0f", groupId.toString());
-    assertTrue(groupId.isMmsGroup());
+    assertTrue(groupId.isMms());
+    assertFalse(groupId.isV1());
+    assertFalse(groupId.isV2());
+    assertFalse(groupId.isPush());
   }
 
   @Test
   public void can_parse_mms() {
-    GroupId groupId = GroupId.parse("__signal_mms_group__!0001020305060708090b0c0d0e0f");
+    GroupId groupId = GroupId.parse("__signal_mms_group__!000102030405060708090a0b0c0d0e0f");
 
-    assertEquals("__signal_mms_group__!0001020305060708090b0c0d0e0f", groupId.toString());
+    assertEquals("__signal_mms_group__!000102030405060708090a0b0c0d0e0f", groupId.toString());
-    assertArrayEquals(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 }, groupId.getDecodedId());
+    assertArrayEquals(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }, groupId.getDecodedId());
-    assertTrue(groupId.isMmsGroup());
+    assertTrue(groupId.isMms());
+    assertFalse(groupId.isV1());
+    assertFalse(groupId.isV2());
+    assertFalse(groupId.isPush());
   }
 
   @SuppressWarnings("ConstantConditions")
@@ -56,16 +109,19 @@ public final class GroupIdTest {
   
   @Test
   public void can_parse_gv1_with_parseNullable() {
-    GroupId groupId = GroupId.parseNullable("__textsecure_group__!0001020305060708090b0c0d0e0f");
+    GroupId groupId = GroupId.parseNullable("__textsecure_group__!000102030405060708090a0b0c0d0e0f");
 
-    assertEquals("__textsecure_group__!0001020305060708090b0c0d0e0f", groupId.toString());
+    assertEquals("__textsecure_group__!000102030405060708090a0b0c0d0e0f", groupId.toString());
-    assertArrayEquals(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 }, groupId.getDecodedId());
+    assertArrayEquals(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }, groupId.getDecodedId());
-    assertFalse(groupId.isMmsGroup());
+    assertFalse(groupId.isMms());
+    assertTrue(groupId.isV1());
+    assertFalse(groupId.isV2());
+    assertTrue(groupId.isPush());
   }
   
   @Test(expected = AssertionError.class)
   public void bad_encoding__bad_prefix__parseNullable() {
-    GroupId.parseNullable("__BAD_PREFIX__!0001020305060708090b0c0d0e0f");
+    GroupId.parseNullable("__BAD_PREFIX__!000102030405060708090a0b0c0d0e0f");
   }
 
   @Test(expected = AssertionError.class)
@@ -80,7 +136,7 @@ public final class GroupIdTest {
 
   @Test(expected = AssertionError.class)
   public void bad_encoding__bad_prefix__parse() {
-    GroupId.parse("__BAD_PREFIX__!0001020305060708090b0c0d0e0f");
+    GroupId.parse("__BAD_PREFIX__!000102030405060708090a0b0c0d0e0f");
   }
   
   @Test(expected = AssertionError.class)
@@ -90,7 +146,7 @@ public final class GroupIdTest {
 
   @Test
   public void get_bytes() {
-    byte[] bytes = { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 };
+    byte[] bytes = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
     GroupId groupId = GroupId.v1(bytes);
 
     assertArrayEquals(bytes, groupId.getDecodedId());
@@ -98,8 +154,8 @@ public final class GroupIdTest {
 
   @Test
   public void equality() {
-    GroupId groupId1 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 });
+    GroupId groupId1 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
-    GroupId groupId2 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 });
+    GroupId groupId2 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
 
     assertNotSame(groupId1, groupId2);
     assertEquals(groupId1, groupId2);
@@ -108,8 +164,8 @@ public final class GroupIdTest {
 
   @Test
   public void inequality_by_bytes() {
-    GroupId groupId1 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 });
+    GroupId groupId1 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
-    GroupId groupId2 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16 });
+    GroupId groupId2 = GroupId.v1(new byte[]{ 0, 3, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
 
     assertNotSame(groupId1, groupId2);
     assertNotEquals(groupId1, groupId2);
@@ -118,8 +174,8 @@ public final class GroupIdTest {
 
   @Test
   public void inequality_of_sms_and_mms() {
-    GroupId groupId1 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 });
+    GroupId groupId1 = GroupId.v1(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
-    GroupId groupId2 = GroupId.mms(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 });
+    GroupId groupId2 = GroupId.mms(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
 
     assertNotSame(groupId1, groupId2);
     assertNotEquals(groupId1, groupId2);
@@ -128,8 +184,84 @@ public final class GroupIdTest {
 
   @Test
   public void inequality_with_null() {
-    GroupId groupId = GroupId.v1(new byte[]{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15 });
+    GroupId groupId = GroupId.v1(new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
 
     assertNotEquals(groupId, null);
   }
+
+  @Test
+  public void require_mms() {
+    GroupId groupId = GroupId.parse("__signal_mms_group__!000102030405060708090a0b0c0d0e0f");
+
+    GroupId.Mms mms = groupId.requireMms();
+
+    assertSame(groupId, mms);
+  }
+
+  @Test
+  public void require_v1_and_push() {
+    GroupId groupId = GroupId.parse("__textsecure_group__!000102030405060708090a0b0c0d0e0f");
+
+    GroupId.V1   v1   = groupId.requireV1();
+    GroupId.Push push = groupId.requirePush();
+
+    assertSame(groupId, v1);
+    assertSame(groupId, push);
+  }
+
+  @Test
+  public void require_v2_and_push() {
+    GroupId groupId = GroupId.parse("__textsecure_group__!9f475f59b2518bff6df22e820803f0e3585bd99e686fa7e7fbfc2f92fd5d953e");
+
+    GroupId.V2   v2   = groupId.requireV2  ();
+    GroupId.Push push = groupId.requirePush();
+
+    assertSame(groupId, v2);
+    assertSame(groupId, push);
+  }
+
+  @Test(expected = AssertionError.class)
+  public void cannot_require_push_of_mms() {
+    GroupId groupId = GroupId.parse("__signal_mms_group__!000102030405060708090a0b0c0d0e0f");
+
+    groupId.requirePush();
+  }
+
+  @Test(expected = AssertionError.class)
+  public void cannot_require_v1_of_mms() {
+    GroupId groupId = GroupId.parse("__signal_mms_group__!000102030405060708090a0b0c0d0e0f");
+
+    groupId.requireV1();
+  }
+
+  @Test(expected = AssertionError.class)
+  public void cannot_require_v2_of_mms() {
+    GroupId groupId = GroupId.parse("__signal_mms_group__!000102030405060708090a0b0c0d0e0f");
+
+    groupId.requireV2();
+  }
+
+  @Test(expected = AssertionError.class)
+  public void cannot_require_v1_of_v2() {
+    GroupId groupId = GroupId.parse("__textsecure_group__!9f475f59b2518bff6df22e820803f0e3585bd99e686fa7e7fbfc2f92fd5d953e");
+
+    groupId.requireV1();
+  }
+
+  @Test(expected = AssertionError.class)
+  public void cannot_require_v2_of_v1() {
+    GroupId groupId = GroupId.parse("__textsecure_group__!000102030405060708090a0b0c0d0e0f");
+
+    groupId.requireV2();
+  }
+
+  @Test(expected = AssertionError.class)
+  public void cannot_create_v1_with_a_v2_length() throws IOException {
+    GroupId.v1(Hex.fromStringCondensed("9f475f59b2518bff6df22e820803f0e3585bd99e686fa7e7fbfc2f92fd5d953e"));
+  }
+
+  @Test(expected = AssertionError.class)
+  public void cannot_create_v2_with_a_v1_length() throws IOException {
+    GroupId.v2(Hex.fromStringCondensed("000102030405060708090a0b0c0d0e0f"));
+  }
 }

app/src/test/java/org/thoughtcrime/securesms/groups/ZkGroupLibraryUtil.java

@@ -0,0 +1,39 @@
+package org.thoughtcrime.securesms.groups;
+
+import org.signal.zkgroup.internal.Native;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeNoException;
+
+class ZkGroupLibraryUtil {
+
+  /**
+   * Attempts to initialize the ZkGroup Native class, which will load the native binaries.
+   * <p>
+   * If that fails to link, then on Unix, it will fail as we rely on that for CI.
+   * <p>
+   * If that fails to link, and it's not Unix, it will skip the test via assumption violation.
+   */
+  static void assumeZkGroupSupportedOnOS() {
+    try {
+      Class.forName(Native.class.getName());
+    } catch (ClassNotFoundException e) {
+      fail();
+    } catch (UnsatisfiedLinkError e) {
+      String osName = System.getProperty("os.name");
+
+      if (isUnix(osName)) {
+        fail("Not able to link native ZkGroup on a key OS: " + osName);
+      } else {
+        assumeNoException("Not able to link native ZkGroup on this operating system: " + osName, e);
+      }
+    }
+  }
+
+  private static boolean isUnix(String osName) {
+    assertNotNull(osName);
+    osName = osName.toLowerCase();
+    return osName.contains("nix") || osName.contains("nux") || osName.contains("aix");
+  }
+}