With AESNI, encrypt 8 blocks in parallel

lib/Crypto/Cipher/__init__.py

@@ -1,3 +1,27 @@
+#
+# A block cipher is instantiated as a combination of:
+# 1. A base cipher (such as AES)
+# 2. A mode of operation (such as CBC)
+#
+# Both items are implemented as C modules.
+#
+# The API of #1 is (replace "AES" with the name of the actual cipher):
+# - AES_start_operaion(key) --> base_cipher_state
+# - AES_encrypt(base_cipher_state, in, out, length)
+# - AES_decrypt(base_cipher_state, in, out, length)
+# - AES_stop_operation(base_cipher_state)
+#
+# Where base_cipher_state is AES_State, a struct with BlockBase (set of
+# pointers to encrypt/decrypt/stop) followed by cipher-specific data.
+#
+# The API of #2 is (replace "CBC" with the name of the actual mode):
+# - CBC_start_operation(base_cipher_state) --> mode_state
+# - CBC_encrypt(mode_state, in, out, length)
+# - CBC_decrypt(mode_state, in, out, length)
+# - CBC_stop_operation(mode_state)
+#
+# where mode_state is a a pointer to base_cipher_state plus mode-specific data.
+
 import os
 
 from Crypto.Cipher._mode_ecb import _create_ecb_cipher