+/* Test key from both GOST R 34.12-2015 and GOST R 34.13-2015. */
+static const unsigned char K[] = {
+ 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,
+};
+
+/* Plaintext from GOST R 34.13-2015 A.1.
+ * First 16 bytes is vector (a) from GOST R 34.12-2015 A.1. */
+static const unsigned char P[] = {
+ 0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x00,0xff,0xee,0xdd,0xcc,0xbb,0xaa,0x99,0x88,
+ 0x00,0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88,0x99,0xaa,0xbb,0xcc,0xee,0xff,0x0a,
+ 0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88,0x99,0xaa,0xbb,0xcc,0xee,0xff,0x0a,0x00,
+ 0x22,0x33,0x44,0x55,0x66,0x77,0x88,0x99,0xaa,0xbb,0xcc,0xee,0xff,0x0a,0x00,0x11,
+};
+
+static void hexdump(const void *ptr, size_t len)