X-Git-Url: https://git.nmode.ca/signal-cli/blobdiff_plain/f6061f95dee516bcd9163460e5702bb73a5e763d..c10910e4660e96c24dce35455c31ec8056d9088c:/src/main/java/org/asamk/signal/manager/GroupUtils.java

diff --git a/src/main/java/org/asamk/signal/manager/GroupUtils.java b/src/main/java/org/asamk/signal/manager/GroupUtils.java
index f4398f94..0d192002 100644
--- a/src/main/java/org/asamk/signal/manager/GroupUtils.java
+++ b/src/main/java/org/asamk/signal/manager/GroupUtils.java
@@ -3,6 +3,10 @@ package org.asamk.signal.manager;
 import org.asamk.signal.storage.groups.GroupInfo;
 import org.asamk.signal.storage.groups.GroupInfoV1;
 import org.asamk.signal.storage.groups.GroupInfoV2;
+import org.signal.zkgroup.InvalidInputException;
+import org.signal.zkgroup.groups.GroupMasterKey;
+import org.signal.zkgroup.groups.GroupSecretParams;
+import org.whispersystems.libsignal.kdf.HKDFv3;
 import org.whispersystems.signalservice.api.messages.SignalServiceDataMessage;
 import org.whispersystems.signalservice.api.messages.SignalServiceGroup;
 import org.whispersystems.signalservice.api.messages.SignalServiceGroupV2;
@@ -25,4 +29,19 @@ public class GroupUtils {
             messageBuilder.asGroupMessage(group);
         }
     }
+
+    public static byte[] getGroupId(GroupMasterKey groupMasterKey) {
+        final GroupSecretParams groupSecretParams = GroupSecretParams.deriveFromMasterKey(groupMasterKey);
+        return groupSecretParams.getPublicParams().getGroupIdentifier().serialize();
+    }
+
+    public static GroupMasterKey deriveV2MigrationMasterKey(byte[] groupId) {
+        try {
+            return new GroupMasterKey(new HKDFv3().deriveSecrets(groupId,
+                    "GV2 Migration".getBytes(),
+                    GroupMasterKey.SIZE));
+        } catch (InvalidInputException e) {
+            throw new AssertionError(e);
+        }
+    }
 }