/**********************************************************************
 *                        gost89.c                                    *
 *             Copyright (c) 2005-2006 Cryptocom LTD                  *
 *         This file is distributed under the same license as OpenSSL *
 *                                                                    *
 *          Implementation of GOST 28147-89 encryption algorithm      *
 *            No OpenSSL libraries required to compile and use        *
 *                              this code                             *
 **********************************************************************/ 
#include <string.h>
#include "gost89.h"
/*-
   Substitution blocks from RFC 4357 
   
   Note: our implementation of gost 28147-89 algorithm 
   uses S-box matrix rotated 90 degrees counterclockwise, relative to 
   examples given in RFC.
  

*/

/* Substitution blocks from test examples for GOST R 34.11-94*/
gost_subst_block GostR3411_94_TestParamSet = {
	{0X1,0XF,0XD,0X0,0X5,0X7,0XA,0X4,0X9,0X2,0X3,0XE,0X6,0XB,0X8,0XC},
	{0XD,0XB,0X4,0X1,0X3,0XF,0X5,0X9,0X0,0XA,0XE,0X7,0X6,0X8,0X2,0XC},
	{0X4,0XB,0XA,0X0,0X7,0X2,0X1,0XD,0X3,0X6,0X8,0X5,0X9,0XC,0XF,0XE},
	{0X6,0XC,0X7,0X1,0X5,0XF,0XD,0X8,0X4,0XA,0X9,0XE,0X0,0X3,0XB,0X2},
	{0X7,0XD,0XA,0X1,0X0,0X8,0X9,0XF,0XE,0X4,0X6,0XC,0XB,0X2,0X5,0X3},
	{0X5,0X8,0X1,0XD,0XA,0X3,0X4,0X2,0XE,0XF,0XC,0X7,0X6,0X0,0X9,0XB},
	{0XE,0XB,0X4,0XC,0X6,0XD,0XF,0XA,0X2,0X3,0X8,0X1,0X0,0X7,0X5,0X9},
	{0X4,0XA,0X9,0X2,0XD,0X8,0X0,0XE,0X6,0XB,0X1,0XC,0X7,0XF,0X5,0X3}
	};  
/* Substitution blocks for hash function 1.2.643.2.9.1.6.1  */
gost_subst_block GostR3411_94_CryptoProParamSet= {
	{0x1,0x3,0xA,0x9,0x5,0xB,0x4,0xF,0x8,0x6,0x7,0xE,0xD,0x0,0x2,0xC},
	{0xD,0xE,0x4,0x1,0x7,0x0,0x5,0xA,0x3,0xC,0x8,0xF,0x6,0x2,0x9,0xB},
	{0x7,0x6,0x2,0x4,0xD,0x9,0xF,0x0,0xA,0x1,0x5,0xB,0x8,0xE,0xC,0x3},
	{0x7,0x6,0x4,0xB,0x9,0xC,0x2,0xA,0x1,0x8,0x0,0xE,0xF,0xD,0x3,0x5},
	{0x4,0xA,0x7,0xC,0x0,0xF,0x2,0x8,0xE,0x1,0x6,0x5,0xD,0xB,0x9,0x3},
	{0x7,0xF,0xC,0xE,0x9,0x4,0x1,0x0,0x3,0xB,0x5,0x2,0x6,0xA,0x8,0xD},
	{0x5,0xF,0x4,0x0,0x2,0xD,0xB,0x9,0x1,0x7,0x6,0x3,0xC,0xE,0xA,0x8},
	{0xA,0x4,0x5,0x6,0x8,0x1,0x3,0x7,0xD,0xC,0xE,0x0,0x9,0x2,0xB,0xF}
	} ;

/* Test paramset from GOST 28147 */
gost_subst_block Gost28147_TestParamSet =
	{
	{0xC,0x6,0x5,0x2,0xB,0x0,0x9,0xD,0x3,0xE,0x7,0xA,0xF,0x4,0x1,0x8},
	{0x9,0xB,0xC,0x0,0x3,0x6,0x7,0x5,0x4,0x8,0xE,0xF,0x1,0xA,0x2,0xD},
	{0x8,0xF,0x6,0xB,0x1,0x9,0xC,0x5,0xD,0x3,0x7,0xA,0x0,0xE,0x2,0x4},
	{0x3,0xE,0x5,0x9,0x6,0x8,0x0,0xD,0xA,0xB,0x7,0xC,0x2,0x1,0xF,0x4},
	{0xE,0x9,0xB,0x2,0x5,0xF,0x7,0x1,0x0,0xD,0xC,0x6,0xA,0x4,0x3,0x8},
	{0xD,0x8,0xE,0xC,0x7,0x3,0x9,0xA,0x1,0x5,0x2,0x4,0x6,0xF,0x0,0xB},
	{0xC,0x9,0xF,0xE,0x8,0x1,0x3,0xA,0x2,0x7,0x4,0xD,0x6,0x0,0xB,0x5},
	{0x4,0x2,0xF,0x5,0x9,0x1,0x0,0x8,0xE,0x3,0xB,0xC,0xD,0x7,0xA,0x6}
	};




/* 1.2.643.2.2.31.1 */
gost_subst_block Gost28147_CryptoProParamSetA= {
	{0xB,0xA,0xF,0x5,0x0,0xC,0xE,0x8,0x6,0x2,0x3,0x9,0x1,0x7,0xD,0x4},
	{0x1,0xD,0x2,0x9,0x7,0xA,0x6,0x0,0x8,0xC,0x4,0x5,0xF,0x3,0xB,0xE},
	{0x3,0xA,0xD,0xC,0x1,0x2,0x0,0xB,0x7,0x5,0x9,0x4,0x8,0xF,0xE,0x6},
	{0xB,0x5,0x1,0x9,0x8,0xD,0xF,0x0,0xE,0x4,0x2,0x3,0xC,0x7,0xA,0x6},
	{0xE,0x7,0xA,0xC,0xD,0x1,0x3,0x9,0x0,0x2,0xB,0x4,0xF,0x8,0x5,0x6},
	{0xE,0x4,0x6,0x2,0xB,0x3,0xD,0x8,0xC,0xF,0x5,0xA,0x0,0x7,0x1,0x9},
	{0x3,0x7,0xE,0x9,0x8,0xA,0xF,0x0,0x5,0x2,0x6,0xC,0xB,0x4,0xD,0x1},
	{0x9,0x6,0x3,0x2,0x8,0xB,0x1,0x7,0xA,0x4,0xE,0xF,0xC,0x0,0xD,0x5}
	};
/* 1.2.643.2.2.31.2 */
gost_subst_block Gost28147_CryptoProParamSetB= 
	{
	{0x0,0x4,0xB,0xE,0x8,0x3,0x7,0x1,0xA,0x2,0x9,0x6,0xF,0xD,0x5,0xC},
	{0x5,0x2,0xA,0xB,0x9,0x1,0xC,0x3,0x7,0x4,0xD,0x0,0x6,0xF,0x8,0xE},
	{0x8,0x3,0x2,0x6,0x4,0xD,0xE,0xB,0xC,0x1,0x7,0xF,0xA,0x0,0x9,0x5},
	{0x2,0x7,0xC,0xF,0x9,0x5,0xA,0xB,0x1,0x4,0x0,0xD,0x6,0x8,0xE,0x3},
	{0x7,0x5,0x0,0xD,0xB,0x6,0x1,0x2,0x3,0xA,0xC,0xF,0x4,0xE,0x9,0x8},
	{0xE,0xC,0x0,0xA,0x9,0x2,0xD,0xB,0x7,0x5,0x8,0xF,0x3,0x6,0x1,0x4},
	{0x0,0x1,0x2,0xA,0x4,0xD,0x5,0xC,0x9,0x7,0x3,0xF,0xB,0x8,0x6,0xE},
	{0x8,0x4,0xB,0x1,0x3,0x5,0x0,0x9,0x2,0xE,0xA,0xC,0xD,0x6,0x7,0xF}
	};
/* 1.2.643.2.2.31.3 */
gost_subst_block Gost28147_CryptoProParamSetC= 
	{
	{0x7,0x4,0x0,0x5,0xA,0x2,0xF,0xE,0xC,0x6,0x1,0xB,0xD,0x9,0x3,0x8},
	{0xA,0x9,0x6,0x8,0xD,0xE,0x2,0x0,0xF,0x3,0x5,0xB,0x4,0x1,0xC,0x7},
	{0xC,0x9,0xB,0x1,0x8,0xE,0x2,0x4,0x7,0x3,0x6,0x5,0xA,0x0,0xF,0xD},
	{0x8,0xD,0xB,0x0,0x4,0x5,0x1,0x2,0x9,0x3,0xC,0xE,0x6,0xF,0xA,0x7},
	{0x3,0x6,0x0,0x1,0x5,0xD,0xA,0x8,0xB,0x2,0x9,0x7,0xE,0xF,0xC,0x4},
	{0x8,0x2,0x5,0x0,0x4,0x9,0xF,0xA,0x3,0x7,0xC,0xD,0x6,0xE,0x1,0xB},
	{0x0,0x1,0x7,0xD,0xB,0x4,0x5,0x2,0x8,0xE,0xF,0xC,0x9,0xA,0x6,0x3},
	{0x1,0xB,0xC,0x2,0x9,0xD,0x0,0xF,0x4,0x5,0x8,0xE,0xA,0x7,0x6,0x3}
	};

/* 1.2.643.2.2.31.4 */ 
gost_subst_block Gost28147_CryptoProParamSetD=
	{
	{0x1,0xA,0x6,0x8,0xF,0xB,0x0,0x4,0xC,0x3,0x5,0x9,0x7,0xD,0x2,0xE},
	{0x3,0x0,0x6,0xF,0x1,0xE,0x9,0x2,0xD,0x8,0xC,0x4,0xB,0xA,0x5,0x7},
	{0x8,0x0,0xF,0x3,0x2,0x5,0xE,0xB,0x1,0xA,0x4,0x7,0xC,0x9,0xD,0x6},
	{0x0,0xC,0x8,0x9,0xD,0x2,0xA,0xB,0x7,0x3,0x6,0x5,0x4,0xE,0xF,0x1},
	{0x1,0x5,0xE,0xC,0xA,0x7,0x0,0xD,0x6,0x2,0xB,0x4,0x9,0x3,0xF,0x8},
	{0x1,0xC,0xB,0x0,0xF,0xE,0x6,0x5,0xA,0xD,0x4,0x8,0x9,0x3,0x7,0x2},
	{0xB,0x6,0x3,0x4,0xC,0xF,0xE,0x2,0x7,0xD,0x8,0x0,0x5,0xA,0x9,0x1},
	{0xF,0xC,0x2,0xA,0x6,0x4,0x5,0x0,0x7,0x9,0xE,0xD,0x1,0xB,0x8,0x3}
	};


const byte CryptoProKeyMeshingKey[]={
	0x69, 0x00, 0x72, 0x22,   0x64, 0xC9, 0x04, 0x23,
    0x8D, 0x3A, 0xDB, 0x96,   0x46, 0xE9, 0x2A, 0xC4,
    0x18, 0xFE, 0xAC, 0x94,   0x00, 0xED, 0x07, 0x12,
    0xC0, 0x86, 0xDC, 0xC2,   0xEF, 0x4C, 0xA9, 0x2B
	};	
/* Initialization of gost_ctx subst blocks*/
static void kboxinit(gost_ctx *c, const gost_subst_block *b)
	{ 
	int i; 
	
	for (i = 0; i < 256; i++)
		{
		c->k87[i] = (b->k8[i>>4] <<4 | b->k7 [i &15])<<24;
		c->k65[i] = (b->k6[i>>4] << 4 | b->k5 [i &15])<<16;
		c->k43[i] = (b->k4[i>>4] <<4  | b->k3 [i &15])<<8;
		c->k21[i] = b->k2[i>>4] <<4  | b->k1 [i &15];

		}
	}

/* Part of GOST 28147 algorithm moved into separate function */
static word32 f(gost_ctx *c,word32 x) 
	{
	x = c->k87[x>>24 & 255] | c->k65[x>>16 & 255]| 
		c->k43[x>> 8 & 255] | c->k21[x & 255]; 
	/* Rotate left 11 bits */ 
	return x<<11 | x>>(32-11);
	}
/* Low-level encryption routine - encrypts one 64 bit block*/
void gostcrypt(gost_ctx *c, const byte *in, byte *out)
	{ 
	register word32 n1, n2; /* As named in the GOST */ 
	n1 = in[0]|(in[1]<<8)|(in[2]<<16)|(in[3]<<24); 
	n2 = in[4]|(in[5]<<8)|(in[6]<<16)|(in[7]<<24); 
	/* Instead of swapping halves, swap names each round */ 
 	 
	n2 ^= f(c,n1+c->k[0]); n1 ^= f(c,n2+c->k[1]); 
	n2 ^= f(c,n1+c->k[2]); n1 ^= f(c,n2+c->k[3]); 
	n2 ^= f(c,n1+c->k[4]); n1 ^= f(c,n2+c->k[5]); 
	n2 ^= f(c,n1+c->k[6]); n1 ^= f(c,n2+c->k[7]); 
  
	n2 ^= f(c,n1+c->k[0]); n1 ^= f(c,n2+c->k[1]);
	n2 ^= f(c,n1+c->k[2]); n1 ^= f(c,n2+c->k[3]);
	n2 ^= f(c,n1+c->k[4]); n1 ^= f(c,n2+c->k[5]);
	n2 ^= f(c,n1+c->k[6]); n1 ^= f(c,n2+c->k[7]);
                               
	n2 ^= f(c,n1+c->k[0]); n1 ^= f(c,n2+c->k[1]);
	n2 ^= f(c,n1+c->k[2]); n1 ^= f(c,n2+c->k[3]);
	n2 ^= f(c,n1+c->k[4]); n1 ^= f(c,n2+c->k[5]);
	n2 ^= f(c,n1+c->k[6]); n1 ^= f(c,n2+c->k[7]);
                               
	n2 ^= f(c,n1+c->k[7]); n1 ^= f(c,n2+c->k[6]);
	n2 ^= f(c,n1+c->k[5]); n1 ^= f(c,n2+c->k[4]);
	n2 ^= f(c,n1+c->k[3]); n1 ^= f(c,n2+c->k[2]);
	n2 ^= f(c,n1+c->k[1]); n1 ^= f(c,n2+c->k[0]);
 
	out[0] = (byte)(n2&0xff);  out[1] = (byte)((n2>>8)&0xff);
	out[2] = (byte)((n2>>16)&0xff); out[3]=(byte)(n2>>24); 
	out[4] = (byte)(n1&0xff);  out[5] = (byte)((n1>>8)&0xff);
	out[6] = (byte)((n1>>16)&0xff); out[7] = (byte)(n1>>24);
	} 
/* Low-level decryption routine. Decrypts one 64-bit block */
void gostdecrypt(gost_ctx *c, const byte *in,byte *out)
	{ 
	register word32 n1, n2; /* As named in the GOST */ 
	n1 = in[0]|(in[1]<<8)|(in[2]<<16)|(in[3]<<24); 
	n2 = in[4]|(in[5]<<8)|(in[6]<<16)|(in[7]<<24); 
	
	n2 ^= f(c,n1+c->k[0]); n1 ^= f(c,n2+c->k[1]); 
	n2 ^= f(c,n1+c->k[2]); n1 ^= f(c,n2+c->k[3]); 
	n2 ^= f(c,n1+c->k[4]); n1 ^= f(c,n2+c->k[5]);
	n2 ^= f(c,n1+c->k[6]); n1 ^= f(c,n2+c->k[7]); 
	
	n2 ^= f(c,n1+c->k[7]); n1 ^= f(c,n2+c->k[6]);
	n2 ^= f(c,n1+c->k[5]); n1 ^= f(c,n2+c->k[4]);
	n2 ^= f(c,n1+c->k[3]); n1 ^= f(c,n2+c->k[2]);
	n2 ^= f(c,n1+c->k[1]); n1 ^= f(c,n2+c->k[0]);
	
	n2 ^= f(c,n1+c->k[7]); n1 ^= f(c,n2+c->k[6]);
	n2 ^= f(c,n1+c->k[5]); n1 ^= f(c,n2+c->k[4]);
	n2 ^= f(c,n1+c->k[3]); n1 ^= f(c,n2+c->k[2]);
	n2 ^= f(c,n1+c->k[1]); n1 ^= f(c,n2+c->k[0]);
	
	n2 ^= f(c,n1+c->k[7]); n1 ^= f(c,n2+c->k[6]);
	n2 ^= f(c,n1+c->k[5]); n1 ^= f(c,n2+c->k[4]);
	n2 ^= f(c,n1+c->k[3]); n1 ^= f(c,n2+c->k[2]);
	n2 ^= f(c,n1+c->k[1]); n1 ^= f(c,n2+c->k[0]);

	out[0] = (byte)(n2&0xff);  out[1] = (byte)((n2>>8)&0xff);
	out[2] = (byte)((n2>>16)&0xff); out[3]=(byte)(n2>>24);
	out[4] = (byte)(n1&0xff);  out[5] = (byte)((n1>>8)&0xff);
	out[6] = (byte)((n1>>16)&0xff); out[7] = (byte)(n1>>24);
	} 

/* Encrypts several blocks in ECB mode */
void gost_enc(gost_ctx *c,const byte *clear,byte *cipher, int blocks)
	{ 
	int i; 
	for(i=0;i<blocks;i++)
		{ 
		gostcrypt(c,clear,cipher); 
		clear+=8;
		cipher+=8;
		}
	}
/* Decrypts several blocks in ECB mode */
void gost_dec(gost_ctx *c, const byte *cipher,byte *clear, int blocks)
	{ 
	int i; 
	for(i=0;i<blocks;i++)
		{ 
		gostdecrypt(c,cipher,clear); 
		clear+=8; 
		cipher+=8;
		}
	}

/* Encrypts several full blocks in CFB mode using 8byte IV */
void gost_enc_cfb(gost_ctx *ctx,const byte *iv,const byte *clear,byte *cipher, int blocks)
	{
	byte cur_iv[8];
	byte gamma[8];
	int i,j;
	const byte *in;
	byte *out;
	memcpy(cur_iv,iv,8);
	for(i=0,in=clear,out=cipher;i<blocks;i++,in+=8,out+=8)
		{
		gostcrypt(ctx,cur_iv,gamma);
		for (j=0;j<8;j++)
			{
			cur_iv[j]=out[j]=in[j]^gamma[j];
			}
		}	
	}	
/* Decrypts several full blocks in CFB mode using 8byte IV */
void gost_dec_cfb(gost_ctx *ctx,const byte *iv,const byte *cipher,byte *clear,  int blocks)
	{
	byte cur_iv[8];
	byte gamma[8];
	int i,j;
	const byte *in;
	byte *out;
	memcpy(cur_iv,iv,8);
	for(i=0,in=cipher,out=clear;i<blocks;i++,in+=8,out+=8)
		{
		gostcrypt(ctx,cur_iv,gamma);
		for (j=0;j<8;j++)
			{
			out[j]=(cur_iv[j]=in[j])^gamma[j];
			}
		}	
	}	

/* Encrypts one block using specified key */
void gost_enc_with_key(gost_ctx *c,byte *key,byte *inblock,byte *outblock) 
	{
	gost_key(c,key);
	gostcrypt(c,inblock,outblock);
	}

/* Set 256 bit  key into context */
void gost_key(gost_ctx *c, const byte *k) 
	{ 
	int i,j; 
	for(i=0,j=0;i<8;i++,j+=4)
		{
		c->k[i]=k[j]|(k[j+1]<<8)|(k[j+2]<<16)|(k[j+3]<<24);
		}		
	} 

/* Retrieve 256-bit key from context */
void gost_get_key(gost_ctx *c, byte *k) 
	{
	int i,j; 
	for(i=0,j=0;i<8;i++,j+=4)
		{
		k[j]=(byte)(c->k[i]& 0xFF);
		k[j+1]=(byte)((c->k[i]>>8 )&0xFF);
		k[j+2]=(byte)((c->k[i]>>16) &0xFF);
		k[j+3]=(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)
	{ 	
	if(!b)
		{
		b=&GostR3411_94_TestParamSet;
		}	
	kboxinit(c,b); 
	}

/* Cleans up key from context */
void gost_destroy(gost_ctx *c)
	{ 
	int i; for(i=0;i<8;i++) c->k[i]=0; 
	} 

/* Compute GOST 28147 mac block 
 * 
 * Parameters
 *   gost_ctx *c - context initalized with substitution blocks and key
 *   buffer - 8-byte mac state buffer
 *   block 8-byte block to process.
 * */
void mac_block(gost_ctx *c,byte *buffer,const  byte *block)
	{
	register word32 n1, n2; /* As named in the GOST */ 
	int i;
	for (i=0; i<8; i++)
		{
		buffer[i]^=block[i];
		}	  
	n1 = buffer[0]|(buffer[1]<<8)|(buffer[2]<<16)|(buffer[3]<<24); 
	n2 = buffer[4]|(buffer[5]<<8)|(buffer[6]<<16)|(buffer[7]<<24); 
	/* Instead of swapping halves, swap names each round */ 
 	 
	n2 ^= f(c,n1+c->k[0]); n1 ^= f(c,n2+c->k[1]); 
	n2 ^= f(c,n1+c->k[2]); n1 ^= f(c,n2+c->k[3]); 
	n2 ^= f(c,n1+c->k[4]); n1 ^= f(c,n2+c->k[5]); 
	n2 ^= f(c,n1+c->k[6]); n1 ^= f(c,n2+c->k[7]); 
  
	n2 ^= f(c,n1+c->k[0]); n1 ^= f(c,n2+c->k[1]);
	n2 ^= f(c,n1+c->k[2]); n1 ^= f(c,n2+c->k[3]);
	n2 ^= f(c,n1+c->k[4]); n1 ^= f(c,n2+c->k[5]);
	n2 ^= f(c,n1+c->k[6]); n1 ^= f(c,n2+c->k[7]);

	buffer[0] = (byte)(n1&0xff);  buffer[1] = (byte)((n1>>8)&0xff);
	buffer[2] = (byte)((n1>>16)&0xff); buffer[3] = (byte)(n1>>24);
	buffer[4] = (byte)(n2&0xff);  buffer[5] = (byte)((n2>>8)&0xff);
	buffer[6] = (byte)((n2>>16)&0xff); buffer[7] = (byte)(n2>>24);
	}

/* Get mac with specified number of bits from MAC state buffer */
void get_mac(byte *buffer,int nbits,byte *out)
	{
	int nbytes= nbits >> 3;
	int rembits = nbits & 7;
	int mask =rembits?((1<rembits)-1):0;
	int i;
	for (i=0;i<nbytes;i++) out[i]=buffer[i];
	if (rembits) out[i]=buffer[i]&mask;
	}	

/* Compute mac of specified length (in bits) from data. 
 * Context should be initialized with key and subst blocks */
int gost_mac(gost_ctx *ctx,int mac_len,const unsigned char *data,
	unsigned int data_len,unsigned char *mac) 
	{
	byte buffer[8]={0,0,0,0,0,0,0,0};
	byte buf2[8];
	unsigned int i;
	for (i=0;i+8<=data_len;i+=8) 
		mac_block(ctx,buffer,data+i);
	if (i<data_len)
		{
		memset(buf2,0,8);
		memcpy(buf2,data+i,data_len-i);
		mac_block(ctx,buffer,buf2);
		i+=8;
		}
	if (i==8)
		{
		memset(buf2,0,8);
		mac_block(ctx,buffer,buf2);
		}
	get_mac(buffer,mac_len,mac);
	return 1;
	}

/* Compute MAC with non-zero IV. Used in some RFC 4357 algorithms */
int gost_mac_iv(gost_ctx *ctx,int mac_len,const unsigned char *iv,const unsigned char *data,
	unsigned int data_len,unsigned char *mac) 
	{
	byte buffer[8];
	byte buf2[8];
	unsigned int i;
	memcpy (buffer,iv,8);
	for (i=0;i+8<=data_len;i+=8) 
		mac_block(ctx,buffer,data+i);
	if (i<data_len)
		{
		memset(buf2,0,8);
		memcpy(buf2,data+i,data_len-i);
		mac_block(ctx,buffer,buf2);
		i+=8;
		}	
	if (i==8)
		{
		memset(buf2,0,8);
		mac_block(ctx,buffer,buf2);
		}
	get_mac(buffer,mac_len,mac);
	return 1;
	}

/* Implements key meshing algorithm by modifing ctx and IV in place */
void cryptopro_key_meshing(gost_ctx *ctx, unsigned char *iv)
	{
	unsigned char newkey[32],newiv[8];
	/* Set static keymeshing key */
	/* "Decrypt" key with keymeshing key */
	gost_dec(ctx,CryptoProKeyMeshingKey,newkey,4);
	/* set new key */
	gost_key(ctx,newkey);
	/* Encrypt iv with new key */
	gostcrypt(ctx,iv,newiv);
	memcpy(iv,newiv,8);
	}