Avoids creating a byte array and recreating it again inside of the Mac instance.

quartz/src/androidMain/kotlin/com/vitorpamplona/quartz/nip44Encryption/Nip44v2.kt

@@ -210,7 +210,7 @@ class Nip44v2 {
             "AAD associated data must be 32 bytes, but it was ${aad.size} bytes"
         }
 
-        return hkdf.extract(aad + message, key)
+        return hkdf.extract(aad, message, key)
     }
 
     fun getMessageKeys(

quartz/src/androidMain/kotlin/com/vitorpamplona/quartz/nip44Encryption/crypto/Hkdf.kt

@@ -37,6 +37,18 @@ class Hkdf(
         return mac.doFinal(key)
     }
 
+    fun extract(
+        key1: ByteArray,
+        key2: ByteArray,
+        salt: ByteArray,
+    ): ByteArray {
+        val mac = Mac.getInstance(algorithm)
+        mac.init(SecretKeySpec(salt, algorithm))
+        mac.update(key1)
+        mac.update(key2)
+        return mac.doFinal()
+    }
+
     fun expand(
         key: ByteArray,
         nonce: ByteArray,