From aaf0d2c49f343e909dc69b487056ca31238ffabf Mon Sep 17 00:00:00 2001
From: Kévin Le Gouguec <kevin.legouguec@airbus.com>
Date: Thu, 21 Mar 2019 16:04:16 +0100
Subject: [implem-python] Nettoyage PEP8
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- espaces avant ':'
- espaces en trop après ','
- parenthèses dans les if
- levée d'exception plutôt que 'return None' implicite

Simplification  de genkat_aead.py  grâce  à l'exception  levée par  le
module.
---
 python/lilliput_ae_2.py | 49 +++++++++++++++++++++++++++----------------------
 1 file changed, 27 insertions(+), 22 deletions(-)

(limited to 'python/lilliput_ae_2.py')

diff --git a/python/lilliput_ae_2.py b/python/lilliput_ae_2.py
index 624fd93..3f72020 100644
--- a/python/lilliput_ae_2.py
+++ b/python/lilliput_ae_2.py
@@ -3,12 +3,13 @@
 """
 
 import lilliput_tbc as ltbc
-from constants import BLOCK_BITS, BLOCK_BYTES
+from constants import BLOCK_BYTES
 from helpers import (
     ArrayToBlockbytesMatrix,
     BlockbytesMatrixToBytes,
     BuildAuth,
     Padding10LSB,
+    TagValidationError,
     XorState
 )
 
@@ -18,30 +19,31 @@ TWEAK_BYTES = TWEAK_BITS//8
 
 
 def TweakTag(j, padded):
-        tweak = [0 for byte in range(0,  TWEAK_BYTES)]
+    tweak = [0 for byte in range(0, TWEAK_BYTES)]
 
-        tweak[TWEAK_BYTES - 1] |= ((j >> 120) & 0xf)
-        for byte in range(TWEAK_BYTES - 2, -1, -1) :
-            tweak[byte] = (j >> (8 * byte)) & 0xff
+    tweak[TWEAK_BYTES - 1] |= ((j >> 120) & 0xf)
+    for byte in range(TWEAK_BYTES - 2, -1, -1):
+        tweak[byte] = (j >> (8 * byte)) & 0xff
 
-        if padded:
-            tweak[TWEAK_BYTES - 1] |= 0x40
+    if padded:
+        tweak[TWEAK_BYTES - 1] |= 0x40
+
+    return tweak
 
-        return tweak
 
-def TweakTagEnd(N) :
-    tweak = [0 for byte in range(0,  TWEAK_BYTES)]
+def TweakTagEnd(N):
+    tweak = [0 for byte in range(0, TWEAK_BYTES)]
 
-    for byte in range(0, TWEAK_BYTES - 1) :
+    for byte in range(0, TWEAK_BYTES - 1):
         tweak[byte] = N[byte]
     tweak[TWEAK_BYTES - 1] = 0x10
 
     return tweak
 
 
-def AddTagJ(tag, j) :
+def AddTagJ(tag, j):
     array_j = [0 for byte in range(0, TWEAK_BYTES)]
-    for byte in range(0, TWEAK_BYTES) :
+    for byte in range(0, TWEAK_BYTES):
         array_j[byte] = (j >> (byte * 8))
 
     xorr = XorState(tag, array_j)
@@ -51,19 +53,19 @@ def AddTagJ(tag, j) :
     return xorr
 
 
-def MesssageAuthTag(M, N, Auth, key) :
+def MesssageAuthTag(M, N, Auth, key):
     l = len(M)//BLOCK_BYTES
     padding_bytes = len(M)%BLOCK_BYTES
 
     tag = list(Auth)
     M = ArrayToBlockbytesMatrix(M)
 
-    for j in range(0, l) :
+    for j in range(0, l):
         tweak = TweakTag(j, False)
         encryption = ltbc.LilliputTBCEnc(tweak, key, M[j])
         tag = XorState(tag, encryption)
 
-    if padding_bytes > 0 :
+    if padding_bytes > 0:
         tweak = TweakTag(l, True)
         m_padded = Padding10LSB(M[l], 8*padding_bytes)
         encryption = ltbc.LilliputTBCEnc(tweak, key, m_padded)
@@ -76,14 +78,14 @@ def MesssageAuthTag(M, N, Auth, key) :
     return tag
 
 
-def MessageEncryption(M, N, tag, key) :
+def MessageEncryption(M, N, tag, key):
     l = len(M)//BLOCK_BYTES
     padding_bytes = len(M)%BLOCK_BYTES
 
     M = ArrayToBlockbytesMatrix(M)
     C = []
 
-    for j in range(0, l) :
+    for j in range(0, l):
         tweak = AddTagJ(tag, j)
         padded_nonce = list(N) + [0x00]
         encryption = ltbc.LilliputTBCEnc(tweak, key, padded_nonce)
@@ -97,8 +99,9 @@ def MessageEncryption(M, N, tag, key) :
 
     return C
 
+
 ################################################################################
-def encrypt(A, M, N, key) :
+def encrypt(A, M, N, key):
     K = list(key)
 
     Auth = BuildAuth(TWEAK_BITS, A, K)
@@ -108,7 +111,7 @@ def encrypt(A, M, N, key) :
     return BlockbytesMatrixToBytes(C), bytes(tag)
 
 
-def decrypt(A, C, N, tag, key) :
+def decrypt(A, C, N, tag, key):
     K = list(key)
     tag = list(tag)
 
@@ -118,5 +121,7 @@ def decrypt(A, C, N, tag, key) :
     Auth = BuildAuth(TWEAK_BITS, A, K)
     tag2 = MesssageAuthTag(M, N, Auth, K)
 
-    if tag == tag2:
-        return M
+    if tag != tag2:
+        raise TagValidationError(tag, tag2)
+
+    return M
-- 
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