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libsignal/src/main/java/org/session/libsignal/crypto/CipherUtil.java

@@ -1,5 +1,8 @@
 package org.session.libsignal.crypto;
 
 public class CipherUtil {
+    // Cipher operations are not thread-safe so we synchronize over them through doFinal to
+    // prevent crashes with quickly repeated encrypt/decrypt operations
+    // https://github.com/mozilla-mobile/android-components/issues/5342
     public static final Object CIPHER_LOCK = new Object();
 }