Merge pull request #17 from Jasuf/master

First try at repacking. Very ugly but works

blkstuff/aes.c

@@ -317,6 +317,29 @@ void oqs_aes128_enc_c(const uint8_t *plaintext, const void *_schedule, uint8_t *
 	xor_round_key(ciphertext, schedule, 10);
 }
 
+// It's not enc nor dec, it's something in between
+void oqs_mhy128_enc_c(const uint8_t *plaintext, const void *_schedule, uint8_t *ciphertext) {
+	const uint8_t *schedule = (const uint8_t *) _schedule;
+	int i; // To count the rounds
+
+	// First Round
+	memcpy(ciphertext, plaintext, 16);
+	xor_round_key(ciphertext, schedule, 0);
+
+	// Middle rounds
+	for (i = 0; i < 9; i++) {
+		sub_bytes_inv(ciphertext, 16);
+		shift_rows_inv(ciphertext);
+		mix_cols_inv(ciphertext);
+		xor_round_key(ciphertext, schedule, i + 1);
+	}
+
+	// Final Round
+	sub_bytes_inv(ciphertext, 16);
+	shift_rows_inv(ciphertext);
+	xor_round_key(ciphertext, schedule, 10);
+}
+
 void oqs_aes128_dec_c(const uint8_t *ciphertext, const void *_schedule, uint8_t *plaintext) {
 	const uint8_t *schedule = (const uint8_t *) _schedule;
 	int i; // To count the rounds
@@ -339,25 +362,24 @@ void oqs_aes128_dec_c(const uint8_t *ciphertext, const void *_schedule, uint8_t
 	xor_round_key(plaintext, schedule, 0);
 }
 
-// It's not enc nor dec, it's something in between
-void oqs_mhy128_enc_c(const uint8_t *plaintext, const void *_schedule, uint8_t *ciphertext) {
+void oqs_mhy128_dec_c(const uint8_t *ciphertext, const void *_schedule, uint8_t *plaintext) {
 	const uint8_t *schedule = (const uint8_t *) _schedule;
 	int i; // To count the rounds
 
-	// First Round
-	memcpy(ciphertext, plaintext, 16);
-	xor_round_key(ciphertext, schedule, 0);
+	// Reverse the final Round
+	memcpy(plaintext, ciphertext, 16);
+	xor_round_key(plaintext, schedule, 10);
+	shift_rows(plaintext);
+	sub_bytes(plaintext, 16);
 
-	// Middle rounds
+	// Reverse the middle rounds
 	for (i = 0; i < 9; i++) {
-		sub_bytes_inv(ciphertext, 16);
-		shift_rows_inv(ciphertext);
-		mix_cols_inv(ciphertext);
-		xor_round_key(ciphertext, schedule, i + 1);
+		xor_round_key(plaintext, schedule, 9 - i);
+		mix_cols(plaintext);
+		shift_rows(plaintext);
+		sub_bytes(plaintext, 16);
 	}
 
-	// Final Round
-	sub_bytes_inv(ciphertext, 16);
-	shift_rows_inv(ciphertext);
-	xor_round_key(ciphertext, schedule, 10);
+	// Reverse the first Round
+	xor_round_key(plaintext, schedule, 0);
 }

blkstuff/magic_constants.h

@@ -1,4 +1,5 @@
 #pragma once
+#include <cassert>
 #include <stdint.h>
 
 // giant constants/precalculated stuff go here
@@ -693,6 +694,17 @@ static inline uint8_t gf256_mul(uint8_t a, uint8_t b)
   return gf256_exp[(gf256_log[a] + gf256_log[b]) % 255];
 }
 
+static inline uint8_t gf256_div(uint8_t a, uint8_t b)
+{
+  if (a == 0)
+    return 0;
+
+  if (b == 0)
+    assert(b == 0);
+
+  return gf256_exp[(255 + gf256_log[a] - gf256_log[b]) % 255];
+}
+
 #pragma pack(1)
 struct blk_header
 {