explain why c3 an c4 are separated

c4.casm

@@ -1,5 +1,9 @@
 # TLS stage 3.
 # Compute ghash H, gctr block, encrypted counter block - needed for Client Finished 
+#
+# Note that circuits 3 and 4 could be combined. The reason why we keep them separate
+# is to later enforce that the same AES key which is used to encrypt Client Finished
+# is also used to encrypt the request to the webserver. 
 
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