From 805c35f310917157b9618122784f4aba7a929344 Mon Sep 17 00:00:00 2001
From: Dmitry Belyavskiy <beldmit@gmail.com>
Date: Thu, 21 Jun 2018 15:28:31 +0300
Subject: [PATCH] ACPKM meshing for Magma

---
 gost89.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 97 insertions(+), 3 deletions(-)

diff --git a/gost89.c b/gost89.c
index ccf338e..3974ab8 100644
--- a/gost89.c
+++ b/gost89.c
@@ -242,6 +242,13 @@ const byte CryptoProKeyMeshingKey[] = {
     0xC0, 0x86, 0xDC, 0xC2, 0xEF, 0x4C, 0xA9, 0x2B
 };
 
+const byte ACPKM_D_const[] = {
+	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 
+	0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F,
+	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 
+	0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F,
+};
+
 /* Initialization of gost_ctx subst blocks*/
 static void kboxinit(gost_ctx * c, const gost_subst_block * b)
 {
@@ -438,7 +445,7 @@ void gost_enc_with_key(gost_ctx * c, byte * key, byte * inblock,
     gostcrypt(c, inblock, outblock);
 }
 
-/* Set 256 bit  key into context */
+/* Set 256 bit gost89 key into context */
 void gost_key(gost_ctx * c, const byte * k)
 {
     int i, j;
@@ -449,7 +456,7 @@ void gost_key(gost_ctx * c, const byte * k)
     }
 }
 
-/* Set 256 bit  key into context */
+/* Set 256 bit Magma key into context */
 void magma_key(gost_ctx * c, const byte * k)
 {
     int i, j;
@@ -460,7 +467,7 @@ void magma_key(gost_ctx * c, const byte * k)
     }
 }
 
-/* Retrieve 256-bit key from context */
+/* Retrieve 256-bit gost89 key from context */
 void gost_get_key(gost_ctx * c, byte * k)
 {
     int i, j;
@@ -472,6 +479,18 @@ void gost_get_key(gost_ctx * c, byte * k)
     }
 }
 
+/* Retrieve 256-bit magma key from context */
+void magma_get_key(gost_ctx * c, byte * k)
+{
+    int i, j;
+    for (i = 0, j = 0; i < 8; i++, j += 4) {
+        k[j + 3] = (byte) (c->k[i] & 0xFF);
+        k[j + 2] = (byte) ((c->k[i] >> 8) & 0xFF);
+        k[j + 1] = (byte) ((c->k[i] >> 16) & 0xFF);
+        k[j + 0] = (byte) ((c->k[i] >> 24) & 0xFF);
+    }
+}
+
 /* Initalize context. Provides default value for subst_block */
 void gost_init(gost_ctx * c, const gost_subst_block * b)
 {
@@ -612,3 +631,78 @@ void cryptopro_key_meshing(gost_ctx * ctx, unsigned char *iv)
     gostcrypt(ctx, iv, newiv);
     memcpy(iv, newiv, 8);
 }
+
+void acpkm_magma_key_meshing(gost_ctx *ctx)
+{
+    unsigned char newkey[32];
+		int i, j;
+		unsigned char buf[8], keybuf[8];
+
+		for (i = 0; i < 4; i++)
+		{
+			for (j = 0; j < 8; j++)
+			{
+				buf[j] = ACPKM_D_const[8*i + 7-j];
+			}
+			gostcrypt(ctx, buf, keybuf);
+			memcpy(newkey+8*i,   keybuf+4, 4);
+			memcpy(newkey+8*i+4, keybuf,   4);
+		}
+    /* set new key */
+    gost_key(ctx, newkey);
+}
+
+#ifdef ENABLE_UNIT_TESTS
+#include <stdio.h>
+#include <string.h>
+
+static void hexdump(FILE *f, const char *title, const unsigned char *s, int l)
+{
+    int n = 0;
+
+    fprintf(f, "%s", title);
+    for (; n < l; ++n) {
+        if ((n % 16) == 0)
+            fprintf(f, "\n%04x", n);
+        fprintf(f, " %02x", s[n]);
+    }
+    fprintf(f, "\n");
+}
+
+int main(void)
+{
+	const unsigned char initial_key[] = {
+		0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF,
+		0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
+		0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10,
+		0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF
+	};
+
+	const unsigned char meshed_key[] = {
+		0x86, 0x3E, 0xA0, 0x17, 0x84, 0x2C, 0x3D, 0x37, 
+		0x2B, 0x18, 0xA8, 0x5A, 0x28, 0xE2, 0x31, 0x7D,
+		0x74, 0xBE, 0xFC, 0x10, 0x77, 0x20, 0xDE, 0x0C, 
+		0x9E, 0x8A, 0xB9, 0x74, 0xAB, 0xD0, 0x0C, 0xA0,
+	};
+
+	unsigned char buf[32];
+
+	gost_ctx ctx;
+	kboxinit(&ctx, &Gost28147_TC26ParamSetZ);
+	magma_key(&ctx, initial_key);
+	magma_get_key(&ctx, buf);
+
+	hexdump(stdout, "Initial key", buf, 32);
+
+	acpkm_magma_key_meshing(&ctx);
+
+	magma_get_key(&ctx, buf);
+	hexdump(stdout, "Meshed key", buf, 32);
+
+	if (memcmp(meshed_key, buf, 32))
+	{
+		fprintf(stderr, "Magma meshing failed");
+	}
+}
+
+#endif
-- 
2.39.2