From 09602fcb6e50fda8245213ac66a340510f21a12f Mon Sep 17 00:00:00 2001
From: Kévin Le Gouguec <kevin.legouguec@airbus.com>
Date: Fri, 5 Jul 2019 15:23:04 +0200
Subject: Suppression d'une variable intermédiaire dans add_felicsref
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Pas sûr que la variable soit utile dans les autres… 🤷
---
 CHANGELOG.txt              | 3 +++
 src/add_felicsref/cipher.c | 9 +++------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.txt b/CHANGELOG.txt
index 2e92008..31acfd2 100644
--- a/CHANGELOG.txt
+++ b/CHANGELOG.txt
@@ -68,6 +68,9 @@ See reference implementation. Further changes:
 - Compute round-tweakeys on the fly to save on RAM, instead of storing all pre-computed round-tweakeys.
   (cipher.c)
 
+- Remove intermediate buffer X in lilliput_tbc_decrypt(), to resemble lilliput_tbc_encrypt().
+  (cipher.c)
+
 add_threshold
 -------------
 
diff --git a/src/add_felicsref/cipher.c b/src/add_felicsref/cipher.c
index 87689df..916f0ab 100644
--- a/src/add_felicsref/cipher.c
+++ b/src/add_felicsref/cipher.c
@@ -168,18 +168,15 @@ void lilliput_tbc_decrypt(
     uint8_t message[BLOCK_BYTES]
 )
 {
-    uint8_t X[BLOCK_BYTES];
-    _state_init(X, ciphertext);
+    _state_init(message, ciphertext);
 
     uint8_t RTK[ROUNDS][ROUND_TWEAKEY_BYTES];
     _compute_round_tweakeys(key, tweak, RTK);
 
     for (size_t i=0; i<ROUNDS-1; i++)
     {
-        _one_round_egfn(X, RTK[ROUNDS-1-i], PERMUTATION_DECRYPTION);
+        _one_round_egfn(message, RTK[ROUNDS-1-i], PERMUTATION_DECRYPTION);
     }
 
-    _one_round_egfn(X, RTK[0], PERMUTATION_NONE);
-
-    memcpy(message, X, BLOCK_BYTES);
+    _one_round_egfn(message, RTK[0], PERMUTATION_NONE);
 }
-- 
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