Pré-calcul de M³

Les résultats changent, mais sont maintenant conformes à ceux de Léo.

1 files changed, 43 insertions, 5 deletions

diff --git a/src/tweakey.c b/src/tweakey.c
index 8f2f7dd..e6f3c36 100644
--- a/src/tweakey.c
+++ b/src/tweakey.c
@@ -90,6 +90,41 @@ static const uint8_t M_1[256] = {
     0xdf, 0xd7, 0xcf, 0xc7, 0xff, 0xf7, 0xef, 0xe7
 };
 
+static const uint8_t M_2[256] = {
+    0x00, 0x40, 0x80, 0xc0, 0x00, 0x40, 0x80, 0xc0,
+    0x08, 0x48, 0x88, 0xc8, 0x08, 0x48, 0x88, 0xc8,
+    0x10, 0x50, 0x90, 0xd0, 0x10, 0x50, 0x90, 0xd0,
+    0x18, 0x58, 0x98, 0xd8, 0x18, 0x58, 0x98, 0xd8,
+    0x20, 0x60, 0xa0, 0xe0, 0x20, 0x60, 0xa0, 0xe0,
+    0x28, 0x68, 0xa8, 0xe8, 0x28, 0x68, 0xa8, 0xe8,
+    0x30, 0x70, 0xb0, 0xf0, 0x30, 0x70, 0xb0, 0xf0,
+    0x38, 0x78, 0xb8, 0xf8, 0x38, 0x78, 0xb8, 0xf8,
+    0x41, 0x01, 0xc1, 0x81, 0x41, 0x01, 0xc1, 0x81,
+    0x49, 0x09, 0xc9, 0x89, 0x49, 0x09, 0xc9, 0x89,
+    0x51, 0x11, 0xd1, 0x91, 0x51, 0x11, 0xd1, 0x91,
+    0x59, 0x19, 0xd9, 0x99, 0x59, 0x19, 0xd9, 0x99,
+    0x61, 0x21, 0xe1, 0xa1, 0x61, 0x21, 0xe1, 0xa1,
+    0x69, 0x29, 0xe9, 0xa9, 0x69, 0x29, 0xe9, 0xa9,
+    0x71, 0x31, 0xf1, 0xb1, 0x71, 0x31, 0xf1, 0xb1,
+    0x79, 0x39, 0xf9, 0xb9, 0x79, 0x39, 0xf9, 0xb9,
+    0x82, 0xc2, 0x02, 0x42, 0x82, 0xc2, 0x02, 0x42,
+    0x8a, 0xca, 0x0a, 0x4a, 0x8a, 0xca, 0x0a, 0x4a,
+    0x92, 0xd2, 0x12, 0x52, 0x92, 0xd2, 0x12, 0x52,
+    0x9a, 0xda, 0x1a, 0x5a, 0x9a, 0xda, 0x1a, 0x5a,
+    0xa2, 0xe2, 0x22, 0x62, 0xa2, 0xe2, 0x22, 0x62,
+    0xaa, 0xea, 0x2a, 0x6a, 0xaa, 0xea, 0x2a, 0x6a,
+    0xb2, 0xf2, 0x32, 0x72, 0xb2, 0xf2, 0x32, 0x72,
+    0xba, 0xfa, 0x3a, 0x7a, 0xba, 0xfa, 0x3a, 0x7a,
+    0xc3, 0x83, 0x43, 0x03, 0xc3, 0x83, 0x43, 0x03,
+    0xcb, 0x8b, 0x4b, 0x0b, 0xcb, 0x8b, 0x4b, 0x0b,
+    0xd3, 0x93, 0x53, 0x13, 0xd3, 0x93, 0x53, 0x13,
+    0xdb, 0x9b, 0x5b, 0x1b, 0xdb, 0x9b, 0x5b, 0x1b,
+    0xe3, 0xa3, 0x63, 0x23, 0xe3, 0xa3, 0x63, 0x23,
+    0xeb, 0xab, 0x6b, 0x2b, 0xeb, 0xab, 0x6b, 0x2b,
+    0xf3, 0xb3, 0x73, 0x33, 0xf3, 0xb3, 0x73, 0x33,
+    0xfb, 0xbb, 0x7b, 0x3b, 0xfb, 0xbb, 0x7b, 0x3b,
+};
+
 static void _multiply_M2(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
 {
     Y[7] = X[5];
@@ -104,11 +139,14 @@ static void _multiply_M2(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
 
 static void _multiply_M3(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
 {
-    uint8_t tmp[LANE_BYTES];
-    memcpy(tmp, X, LANE_BYTES);
-
-    _multiply_M2(X, tmp);
-    _multiply_M(tmp, Y);
+    Y[7] = X[5]<<3   ^ X[4];
+    Y[6] = X[5]<<6   ^ M_1[X[4]] ^ X[3];
+    Y[5] = M_2[X[4]] ^ M_1[X[3]] ^ X[2];
+    Y[4] = X[6]<<2   ^ X[3]>>6   ^ X[2]>>3 ^ X[1];
+    Y[3] = X[5]<<2   ^ X[0];
+    Y[2] = X[7]      ^ X[5]<<6   ^ X[4]<<2;
+    Y[1] = X[6];
+    Y[0] = X[5];
 }
 
 static void _multiply_MR(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])