text:  
  /**********************************************************************
   *                        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);
  	}
  