[implem-python] Réécriture de certains range() dans tbc.py

IME, itérer sur un range() est rarement la façon la plus expressive de
faire les choses ; les alternatives imposent une structure qui rendent
l'intention  plus claire.  E.g. quand  on voit  une compréhension,  on
comprend que l'auteur cherche à  filtrer et/ou transformer ce sur quoi
il itère.

Réutilisation  de  xor_state(),  renommé  xor()  puisqu'il  sert  dans
plusieurs situations.

Séparation  de   ce  xor()  et   des  fonctions  communes   aux  modes
authentifiés pour éviter un import circulaire.

1 files changed, 10 insertions, 10 deletions

diff --git a/src/add_python/lilliput/ae_mode_1.py b/src/add_python/lilliput/ae_mode_1.py
index cc550e8..efa0b6f 100644
--- a/src/add_python/lilliput/ae_mode_1.py
+++ b/src/add_python/lilliput/ae_mode_1.py
@@ -21,13 +21,13 @@ using Lilliput-AE's nonce-respecting mode based on ΘCB3.
 from enum import Enum
 
 from .constants import BLOCK_BYTES, NONCE_BYTES
-from .helpers import (
+from .ae_common import (
     bytes_to_block_matrix,
     block_matrix_to_bytes,
     build_auth,
     pad10,
     TagValidationError,
-    xor_state
+    xor
 )
 from . import tbc
 
@@ -92,7 +92,7 @@ def _treat_message_enc(M, N, key):
     C = []
 
     for j in range(0, l):
-        checksum = xor_state(checksum, M[j])
+        checksum = xor(checksum, M[j])
         tweak = _tweak_message(N, j, _MessageTweak.BLOCK)
         C.append(tbc.encrypt(tweak, key, M[j]))
 
@@ -102,12 +102,12 @@ def _treat_message_enc(M, N, key):
 
     else:
         m_padded = pad10(M[l])
-        checksum = xor_state(checksum, m_padded)
+        checksum = xor(checksum, m_padded)
         tweak = _tweak_message(N, l, _MessageTweak.PAD)
         pad = tbc.encrypt(tweak, key, [0 for byte in range(0, BLOCK_BYTES)])
 
         lower_part = _low_part(pad, padding_bytes*8)
-        C.append(xor_state(M[l], lower_part))
+        C.append(xor(M[l], lower_part))
         tweak_final = _tweak_message(N, l+1, _MessageTweak.FINAL)
         Final = tbc.encrypt(tweak_final, key, checksum)
 
@@ -126,7 +126,7 @@ def _treat_message_dec(C, N, key):
     for j in range(0, l):
         tweak = _tweak_message(N, j, _MessageTweak.BLOCK)
         M.append(tbc.decrypt(tweak, key, C[j]))
-        checksum = xor_state(checksum, M[j])
+        checksum = xor(checksum, M[j])
 
     if padding_bytes == 0:
         tweak = _tweak_message(N, l, _MessageTweak.NO_PADDING)
@@ -136,10 +136,10 @@ def _treat_message_dec(C, N, key):
         tweak = _tweak_message(N, l, _MessageTweak.PAD)
         pad = tbc.encrypt(tweak, key, [0 for byte in range(0, BLOCK_BYTES)])
         lower_part = _low_part(pad, padding_bytes*8)
-        M.append(xor_state(C[l], lower_part))
+        M.append(xor(C[l], lower_part))
 
         m_padded = pad10(M[l])
-        checksum = xor_state(checksum, m_padded)
+        checksum = xor(checksum, m_padded)
         tweak_final = _tweak_message(N, l+1, _MessageTweak.FINAL)
         Final = tbc.encrypt(tweak_final, key, checksum)
 
@@ -151,7 +151,7 @@ def encrypt(A, M, N, key):
 
     Auth = build_auth(TWEAK_BITS, A, K)
     (Final, C) = _treat_message_enc(M, N, K)
-    tag = xor_state(Auth, Final)
+    tag = xor(Auth, Final)
 
     return block_matrix_to_bytes(C), bytes(tag)
 
@@ -162,7 +162,7 @@ def decrypt(A, C, N, tag, key):
 
     Auth = build_auth(TWEAK_BITS, A, K)
     (Final, M) = _treat_message_dec(C, N, K)
-    tag2 = xor_state(Auth, Final)
+    tag2 = xor(Auth, Final)
 
     if tag != tag2:
         raise TagValidationError(tag, tag2)