1 files changed, 41 insertions, 50 deletions

diff --git a/src/cipher.c b/src/cipher.c
index 7f1152a..4190359 100644
--- a/src/cipher.c
+++ b/src/cipher.c
@@ -26,18 +26,9 @@ const uint8_t PERMUTATIONS[2][BLOCK_BYTES] = {
 };
 
 
-struct cipher_state
+static void _state_init(uint8_t X[BLOCK_BYTES], const uint8_t message[BLOCK_BYTES])
 {
-    uint8_t X[BLOCK_BYTES];
-};
-
-
-typedef struct cipher_state cipher_state;
-
-
-static void _state_init(cipher_state *X, const uint8_t message[BLOCK_BYTES])
-{
-    memcpy(X->X, message, sizeof(X->X));
+    memcpy(X, message, BLOCK_BYTES);
 }
 
 
@@ -47,27 +38,27 @@ static void _compute_round_tweakeys(
     uint8_t RTK[ROUNDS][ROUND_TWEAKEY_BYTES]
 )
 {
-    tweakey_state TK;
-    tweakey_state_init(&TK, key, tweak);
-    tweakey_state_extract(&TK, RTK[0], 0);
+    uint8_t TK[TWEAKEY_BYTES];
+    tweakey_state_init(TK, key, tweak);
+    tweakey_state_extract(TK, 0, RTK[0]);
 
     for (uint8_t i=1; i<ROUNDS; i++)
     {
-        tweakey_state_update(&TK);
-        tweakey_state_extract(&TK, RTK[i], i);
+        tweakey_state_update(TK);
+        tweakey_state_extract(TK, i, RTK[i]);
     }
 }
 
 
-static void _nonlinear_layer(cipher_state *X, const uint8_t RTK[ROUND_TWEAKEY_BYTES])
+static void _nonlinear_layer(uint8_t X[BLOCK_BYTES], const uint8_t RTK[ROUND_TWEAKEY_BYTES])
 {
     uint8_t F[ROUND_TWEAKEY_BYTES];
-    for (size_t j=0; j<sizeof(F); j++)
+    for (size_t j=0; j<ROUND_TWEAKEY_BYTES; j++)
     {
-        F[j] = X->X[j] ^ RTK[j];
+        F[j] = X[j] ^ RTK[j];
     }
 
-    for (size_t j=0; j<sizeof(F); j++)
+    for (size_t j=0; j<ROUND_TWEAKEY_BYTES; j++)
     {
         F[j] = S[F[j]];
     }
@@ -75,29 +66,29 @@ static void _nonlinear_layer(cipher_state *X, const uint8_t RTK[ROUND_TWEAKEY_BY
     for (size_t j=0; j<8; j++)
     {
         size_t dest_j = 15-j;
-        X->X[dest_j] ^= F[j];
+        X[dest_j] ^= F[j];
     }
 }
 
-static void _linear_layer(cipher_state *X)
+static void _linear_layer(uint8_t X[BLOCK_BYTES])
 {
-    X->X[15] ^= X->X[1];
-    X->X[15] ^= X->X[2];
-    X->X[15] ^= X->X[3];
-    X->X[15] ^= X->X[4];
-    X->X[15] ^= X->X[5];
-    X->X[15] ^= X->X[6];
-    X->X[15] ^= X->X[7];
-
-    X->X[14] ^= X->X[7];
-    X->X[13] ^= X->X[7];
-    X->X[12] ^= X->X[7];
-    X->X[11] ^= X->X[7];
-    X->X[10] ^= X->X[7];
-    X->X[9]  ^= X->X[7];
+    X[15] ^= X[1];
+    X[15] ^= X[2];
+    X[15] ^= X[3];
+    X[15] ^= X[4];
+    X[15] ^= X[5];
+    X[15] ^= X[6];
+    X[15] ^= X[7];
+
+    X[14] ^= X[7];
+    X[13] ^= X[7];
+    X[12] ^= X[7];
+    X[11] ^= X[7];
+    X[10] ^= X[7];
+    X[9]  ^= X[7];
 }
 
-static void _permutation_layer(cipher_state *X, permutation p)
+static void _permutation_layer(uint8_t X[BLOCK_BYTES], permutation p)
 {
     if (p == PERMUTATION_NONE)
     {
@@ -105,17 +96,17 @@ static void _permutation_layer(cipher_state *X, permutation p)
     }
 
     uint8_t X_old[BLOCK_BYTES];
-    memcpy(X_old, X, sizeof(X_old));
+    memcpy(X_old, X, BLOCK_BYTES);
 
     const uint8_t *pi = PERMUTATIONS[p];
 
     for (size_t j=0; j<BLOCK_BYTES; j++)
     {
-        X->X[pi[j]] = X_old[j];
+        X[pi[j]] = X_old[j];
     }
 }
 
-static void _one_round_egfn(cipher_state *X, const uint8_t RTK[ROUND_TWEAKEY_BYTES], permutation p)
+static void _one_round_egfn(uint8_t X[BLOCK_BYTES], const uint8_t RTK[ROUND_TWEAKEY_BYTES], permutation p)
 {
     _nonlinear_layer(X, RTK);
     _linear_layer(X);
@@ -130,20 +121,20 @@ void lilliput_tbc_encrypt(
     uint8_t ciphertext[BLOCK_BYTES]
 )
 {
-    cipher_state X;
-    _state_init(&X, message);
+    uint8_t X[BLOCK_BYTES];
+    _state_init(X, message);
 
     uint8_t RTK[ROUNDS][ROUND_TWEAKEY_BYTES];
     _compute_round_tweakeys(key, tweak, RTK);
 
     for (uint8_t i=0; i<ROUNDS-1; i++)
     {
-        _one_round_egfn(&X, RTK[i], PERMUTATION_ENCRYPTION);
+        _one_round_egfn(X, RTK[i], PERMUTATION_ENCRYPTION);
     }
 
-    _one_round_egfn(&X, RTK[ROUNDS-1], PERMUTATION_NONE);
+    _one_round_egfn(X, RTK[ROUNDS-1], PERMUTATION_NONE);
 
-    memcpy(ciphertext, X.X, BLOCK_BYTES);
+    memcpy(ciphertext, X, BLOCK_BYTES);
 }
 
 void lilliput_tbc_decrypt(
@@ -153,18 +144,18 @@ void lilliput_tbc_decrypt(
     uint8_t message[BLOCK_BYTES]
 )
 {
-    cipher_state X;
-    _state_init(&X, ciphertext);
+    uint8_t X[BLOCK_BYTES];
+    _state_init(X, ciphertext);
 
     uint8_t RTK[ROUNDS][ROUND_TWEAKEY_BYTES];
     _compute_round_tweakeys(key, tweak, RTK);
 
     for (uint8_t i=0; i<ROUNDS-1; i++)
     {
-        _one_round_egfn(&X, RTK[ROUNDS-1-i], PERMUTATION_DECRYPTION);
+        _one_round_egfn(X, RTK[ROUNDS-1-i], PERMUTATION_DECRYPTION);
     }
 
-    _one_round_egfn(&X, RTK[0], PERMUTATION_NONE);
+    _one_round_egfn(X, RTK[0], PERMUTATION_NONE);
 
-    memcpy(message, X.X, BLOCK_BYTES);
+    memcpy(message, X, BLOCK_BYTES);
 }