Kuznechik_Fast.c

/*
                                        Implementation Of GOST - R- 3412-2015 (Kuznechik)  


Author: AjayBadrinath
Date :  18-01-24
Version :1.4
                Version Changelog: (25-01-24)
                    1.Ported  From Python ...     (_/)
                    2.Extended Support For Arbitrary Prescision Numbers(gmp).(_/)
                    3.Ported comments.
                    4.Parallize operation with openmpi.(partly) Optimizing the heck off this
                    5. Performance Boost 100% (40 ms ENC OP to 4 ms).
                    6. Current Encryption Rate 6kbps. Need to Bump to 1Mbps.


C Header Implementing the Kuznechik Cipher . This is a cipher Proposed by the Russian Security Standard GOST.
    
    The Technical Specifications of this cipher are in the pdf archive in Russian :
    https://web.archive.org/web/20150924113434/http://tc26.ru/standard/gost/GOST_R_3412-2015.pdf
    
    Compared to the previous implementation of the GOST(MAGMA) Cipher which is of 64 bit block,
    
    Kuznechik is a 128 bit block cipher unlike its cousin MAGMA it is rather based on SP Network rather than the 
    Fiestel System .

    Note: Reading the source and understanding the same WILL Require Some Elementary Knowledge of Galois Field Arithmetic + Number Theory . 
    
    Some transformations are done using the same Pls Refer:
    
        1.https://math.stackexchange.com/questions/245621/arithmetic-operations-in-galois-field
        2.https://en.wikipedia.org/wiki/Kuznyechik
        3.The Russian Spec itself
        4.https://stackoverflow.com/questions/13202758/multiplying-two-polynomials
        5.With Support from gmp and openmpi


*/

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <gmp.h>
#include <assert.h>
#include <sys/time.h>
#include <time.h>
#include <omp.h>

/**
 * @brief 
 * Constants:
           
            
            Since this cipher is designed on the lines of Being a SP Network Cipher we have these s-boxes / permute-boxes.
           
            pi     : Used as non-linear bijective transformation    
            
            pi_inv : Used as non-linear bijective transformation
            
            Note   : Mathematically Speaking the inv (fn(x))->x 
                So pi_inv(pi(x))=>x So the pi_inv can safely be called as pi inverse (inv_p-box)
            
            _map   : Iterator Array For the sake of conveinience used for Linear Transformation Constants (c)*nabla(x)
            
            MASK_32: This Acts as MASK as the name suggests to filter bits (32*4-bit )and prevent overflow 
                    ik the name is misleading as it was named after 32 * hex not 32 bits so 128 bits(32*4)
    
 * 
 */

int  pi[]={
    252, 238, 221, 17, 207, 110, 49, 22, 251, 196, 250, 218, 35, 197, 4, 77, 233,
119, 240, 219, 147, 46, 153, 186, 23, 54, 241, 187, 20, 205, 95, 193, 249, 24, 101,
90, 226, 92, 239, 33, 129, 28, 60, 66, 139, 1, 142, 79, 5, 132, 2, 174, 227, 106, 143,
160, 6, 11, 237, 152, 127, 212, 211, 31, 235, 52, 44, 81, 234, 200, 72, 171, 242, 42,
104, 162, 253, 58, 206, 204, 181, 112, 14, 86, 8, 12, 118, 18, 191, 114, 19, 71, 156,
183, 93, 135, 21, 161, 150, 41, 16, 123, 154, 199, 243, 145, 120, 111, 157, 158, 178,
177, 50, 117, 25, 61, 255, 53, 138, 126, 109, 84, 198, 128, 195, 189, 13, 87, 223,
245, 36, 169, 62, 168, 67, 201, 215, 121, 214, 246, 124, 34, 185, 3, 224, 15, 236,
222, 122, 148, 176, 188, 220, 232, 40, 80, 78, 51, 10, 74, 167, 151, 96, 115, 30, 0,
98, 68, 26, 184, 56, 130, 100, 159, 38, 65, 173, 69, 70, 146, 39, 94, 85, 47, 140, 163,
165, 125, 105, 213, 149, 59, 7, 88, 179, 64, 134, 172, 29, 247, 48, 55, 107, 228, 136,
217, 231, 137, 225, 27, 131, 73, 76, 63, 248, 254, 141, 83, 170, 144, 202, 216, 133,
97, 32, 113, 103, 164, 45, 43, 9, 91, 203, 155, 37, 208, 190, 229, 108, 82, 89, 166,
116, 210, 230, 244, 180, 192, 209, 102, 175, 194, 57, 75, 99, 182
};

int pi_inv[]={
    165, 45, 50, 143, 14, 48, 56, 192, 84, 230, 158,
    57, 85, 126, 82, 145, 100, 3, 87, 90, 28, 96,
    7, 24, 33, 114, 168, 209, 41, 198, 164, 63, 224,
    39, 141, 12, 130, 234, 174, 180, 154, 99, 73, 229,
    66, 228, 21, 183, 200, 6, 112, 157, 65, 117, 25,
    201, 170, 252, 77, 191, 42, 115, 132, 213, 195, 175,
    43, 134, 167, 177, 178, 91, 70, 211, 159, 253, 212,
    15, 156, 47, 155, 67, 239, 217, 121, 182, 83, 127,
    193, 240, 35, 231, 37, 94, 181, 30, 162, 223, 166,
    254, 172, 34, 249, 226, 74, 188, 53, 202, 238, 120,
    5, 107, 81, 225, 89, 163, 242, 113, 86, 17, 106,
    137, 148, 101, 140, 187, 119, 60, 123, 40, 171, 210,
    49, 222, 196, 95, 204, 207, 118, 44, 184, 216, 46,
    54, 219, 105, 179, 20, 149, 190, 98, 161, 59, 22,
    102, 233, 92, 108, 109, 173, 55, 97, 75, 185, 227,
    186, 241, 160, 133, 131, 218, 71, 197, 176, 51, 250,
    150, 111, 110, 194, 246, 80, 255, 93, 169, 142, 23,
    27, 151, 125, 236, 88, 247, 31, 251, 124, 9, 13,
    122, 103, 69, 135, 220, 232, 79, 29, 78, 4, 235,
    248, 243, 62, 61, 189, 138, 136, 221, 205, 11, 19,
    152, 2, 147, 128, 144, 208, 36, 52, 203, 237, 244,
    206, 153, 16, 68, 64, 146, 58, 1, 38, 18, 26,
    72, 104, 245, 129, 139, 199, 214, 32, 10, 8, 0,
    76, 215, 116 
};

#define mask_128 "ffffffffffffffffffffffffffffffff"


/*FUNCTION HEADER DEFINITION REGION*/


/**
 * @brief 
 *  Functions pertaining to gmp returns void . as params are implicitly changed 
 * 
 * @param res 
 * @param x 
 */



/**
 * @brief  [Tag] [ENCRYPTION]
 * 
 */


void S_Transformation(mpz_t ,mpz_t );
void L_Transformation(mpz_t ,mpz_t );
void R_Transformation(mpz_t ,mpz_t );
void encrypt(mpz_t ,mpz_t ,mpz_t ,mpz_t*);



/**
 * @brief [Tag] [DECRYPTION]
 * 
 */


void L_Transformation_inverse(mpz_t ,mpz_t );
void R_Transformation_inverse(mpz_t ,mpz_t );
void S_Inv_Transformation(mpz_t ,mpz_t );
void decrypt(mpz_t ,mpz_t ,mpz_t );




/**
 * @brief [Tag] [Utils/Misc/....]
 * 
 */



int deg_Poly_V_128(mpz_t );
void Multiply_Poly_V_128(mpz_t ,mpz_t ,mpz_t );
void Mod_Poly_Reduction(mpz_t ,mpz_t ,mpz_t );
void Round_constant(mpz_t ,int );


/**
 * @brief [Tag] [DECRYPTION] [ENCRYPTION]
 * 
 */


void linear_Transformation(mpz_t ,mpz_t );



/**
 * @brief [Tag] [KeyGen - symmetric_Key ]
 * 
 */


mpz_t*  F_Transformation(mpz_t ,mpz_t ,mpz_t );
mpz_t* Key_Schedule(mpz_t );


/*END OF FUNCTION HEADER*/



/**
 * @brief 
 *          
 *          Tag:[Used in Encryption]
            Function to Apply pi(p-box )to the input in the domain (V(128)->V(128)).

            Parameters:
                x: 128 bit input to Be substituted with pi
            Returns   :
                pi(x) with each nibble .

 * 
 * @param res 
 * @param x 
 */


void S_Transformation(mpz_t res,mpz_t x){
    mpz_t s,tmp,tmp2,x_tmp;
    mpz_init(s);
    mpz_init(tmp);
    mpz_init(x_tmp);
    mpz_init(tmp2);
    mpz_t mask_8;
    mpz_init(mask_8);
    mpz_set_ui(s,0);
    mpz_set_ui(tmp,0);
    mpz_set_ui(tmp2,0);
    mpz_set_ui(x_tmp,0);
    mpz_set_str(mask_8,"ff",16);

    for(int i=15;i>=0;i--){

        mpz_set(x_tmp,x);
        mpz_mul_2exp(s, s, 8);
        mpz_tdiv_q_2exp(x_tmp, x_tmp, 8*i);
        mpz_and(tmp,x_tmp,mask_8);
        mpz_set_ui(tmp2,pi[mpz_get_ui(tmp)]);
        mpz_xor(s,s,tmp2);


    }
    mpz_set(res,s);
    mpz_clear(tmp);
    mpz_clear(tmp2);
    mpz_clear(s);
    mpz_clear(mask_8);
    mpz_clear(x_tmp);
}


/**
 * @brief 
 *          Tag:[ Used in Decryption ]
            Function to Apply pi_inv(p_inv-box )to the input in the domain (V(128)->V(128)). 

            Parameters:
                x: 128 bit input to Be substituted with pi_inv
            Returns   :
                pi_inv(x) with each nibble .
 * @param res 
 * @param x 
 */


void S_Inv_Transformation(mpz_t res,mpz_t x){
    mpz_t s,tmp,tmp2,x_tmp;
    mpz_init(s);
    mpz_init(tmp);
    mpz_init(x_tmp);
    mpz_init(tmp2);
    mpz_t mask_8;
    mpz_init(mask_8);
    mpz_set_ui(s,0);
    mpz_set_ui(tmp,0);
    mpz_set_ui(tmp2,0);
    mpz_set_ui(x_tmp,0);
    mpz_set_str(mask_8,"ff",16);

    for(int i=15;i>=0;i--){
        mpz_set(x_tmp,x);
        mpz_mul_2exp(s, s, 8);
        mpz_tdiv_q_2exp(x_tmp, x_tmp, 8*i);
        mpz_and(tmp,x_tmp,mask_8);
        mpz_set_ui(tmp2,pi_inv[mpz_get_ui(tmp)]);
        mpz_xor(s,s,tmp2);

    }
    mpz_set(res,s);
    mpz_clear(tmp);
    mpz_clear(tmp2);
    mpz_clear(s);
    mpz_clear(mask_8);
    mpz_clear(x_tmp);
}

/**
 * @brief 
 *          Tag:[Misc]
            This is a helper function for Mod_Reduction. Computes the highest degree for a given polynomial:
            eg:11010 -> 4

            Parameters:
                x: A binary Number / Polynomial Representation 
            Returns:
                Highest Degree for the given polynomial
 * 
 * @param x 
 * @return int 
 */

int deg_Poly_V_128(mpz_t x){
    int deg=0;
    mpz_t tmp;
    mpz_init(tmp);
    mpz_set(tmp,x);
    while (mpz_get_ui(tmp)!=0){
        deg++;
        mpz_tdiv_q_2exp(tmp,tmp,1);
    }
    mpz_clear(tmp);
    return deg;

}

/**
 * @brief 
 *          Tag: [Used in Encryption]
            Function to perform R Transformation in the domain(V(128)->V(128))
            
            Parameters:
                 x: 128 bit output from applying S-box transformation
            
            Returns:
                 L(x(15)...x(0))||x(15)....x(1) -> 128 bit
 * 
 * @param res 
 * @param x 
 */


void R_Transformation(mpz_t res,mpz_t x){
    mpz_t _res_lin_,_shift_r_120,_shr_8,_xor_,result,_x;
    mpz_init(_res_lin_);
    mpz_init(result);
    mpz_init(_x);
    mpz_set(_x,x);
    mpz_init(_shift_r_120);
    mpz_init(_shr_8);
    mpz_init(_xor_);
    linear_Transformation(_res_lin_,_x);
    mpz_mul_2exp(_shift_r_120,_res_lin_,120);
    mpz_tdiv_q_2exp(_shr_8,_x,8);
    mpz_xor(result,_shift_r_120,_shr_8);
    mpz_set(res,result);
    mpz_clear(_x);
    mpz_clear(result);
    mpz_clear(_res_lin_);
    mpz_clear(_shift_r_120);
    mpz_clear(_shr_8);
    mpz_clear(_xor_);

}

/**
 * @brief 
 *          Tag:[ Used in Decryption ]
            Function to perform the inverse of R_Transformation in the domain(V(128)->V(128)) 

            Parameters:
                x: 128 bit input from L_Transformation_inverse function 
            Returns   :
                x(14)||x(13)...||x(0)||L(x(14)||x(13)||...||x(0)||x(15)) -> 128 bit 

 * 
 * @param res 
 * @param x 
 */

void R_Transformation_inverse(mpz_t res,mpz_t x){
    mpz_t _res_lin_,_shift_r_120,_shl_8,_xor_,result,_x,mask,_and;
    mpz_init(_res_lin_);
    mpz_init(result);
    mpz_init(mask);
    mpz_init(_and);
    mpz_init(_x);
    mpz_set(_x,x);
    mpz_init(_shift_r_120);
    mpz_set_str(mask,"ff",16);
    mpz_init(_shl_8);
    mpz_init(_xor_);
    mpz_mul_2exp(_shl_8,_x,8);
    mpz_tdiv_q_2exp(_shift_r_120,_x,120);
    mpz_and(_and,_shift_r_120,mask);
    mpz_xor(_xor_,_and,_shl_8);
    linear_Transformation(_res_lin_,_xor_);
    mpz_xor(result,_res_lin_,_shl_8);
    mpz_set(res,result);
    mpz_clear(_x);
    mpz_clear(_and);
    mpz_clear(result);
    mpz_clear(_res_lin_);
    mpz_clear(mask);
    mpz_clear(_shift_r_120);
    mpz_clear(_shl_8);
    mpz_clear(_xor_);

}

/**
 * @brief 
 * 
 *          Tag:[Misc.]
            The Delta Function Defined in the GOST Spec .
            Utility Function to Multiply two Polynomials in binary to put it simply.
            Essentially applies (x<< degree y)+(x<<degree  y)...where + refers to xor operation
            Parameters:
                x: Binary Polynomial 
                y: Binary Polynomial
            Returns:
                x*y -> Product of two polynomials.


 * 
 * @param res 
 * @param x 
 * @param y 
 */


void Multiply_Poly_V_128(mpz_t res,mpz_t x ,mpz_t y){
    mpz_t c,lsh_deg,tmp,ones,_x,_y,_res;
    
    mpz_init(c);
    mpz_init(lsh_deg);
    mpz_init(tmp);
    mpz_init(ones);
    mpz_init(_x);
    mpz_init(_y);
    mpz_init(_res);
    mpz_set(_x,x);
    mpz_set(_y,y);
    mpz_set_ui(c,0);
    mpz_set_str(ones,"1",10);
    int degree=0;
    while (mpz_get_ui(_y)!=0){
        mpz_and(tmp,_y,ones);
        if(mpz_get_ui(tmp)==1){
            mpz_mul_2exp(lsh_deg,_x,degree);
            mpz_xor(c,c,lsh_deg);
        }
        degree=degree+1;
        mpz_tdiv_q_2exp(_y,_y,1);

    }
    mpz_set(res,c);
    mpz_clear(_x);
    mpz_clear(_y);
    mpz_clear(_res);
    mpz_clear(lsh_deg);
    mpz_clear(c);
    mpz_clear(tmp);
    mpz_clear(ones);



}



/**
 * @brief 
 *          Tag:[Misc]
            Function to compute Mod for a given binary Polynomial in the field of GF(2) F->{0,1}
            Essentially iterate till deg(z) <deg(mod):while performing (m<<diff) whrere diff is the 
            difference between the highest power of z and m itself

            Parameters:
                x:A binary polynomial to be reduced.
                m:Modulus binary Number .(For this Cipher We use )
                GF(2)[x]->p(x)=x**8+x**7+x**6+x+1 (111000011) as mod

            Returns:
                z mod m
 * 
 * @param res 
 * @param x 
 * @param m 
 */

void Mod_Poly_Reduction(mpz_t res,mpz_t x,mpz_t m){
    mpz_t z,tmp;
    mpz_init(z);
    mpz_init(tmp);
    int difference=0;
    mpz_set(z,x);
    int tmp1,tmp2;
    while (1){
        tmp1=deg_Poly_V_128(z);
        tmp2=deg_Poly_V_128(m);
        if((tmp1<tmp2)){
            break;
        }
        else{
            difference=tmp1-tmp2;

            mpz_mul_2exp(tmp,m,difference);
            mpz_xor(z,z,tmp);

        }
    }
    mpz_set(res,z);
    mpz_clear(tmp);
    //mpz_clear(tmp1);
    //mpz_clear(tmp2);
    mpz_clear(z);
}

/**
 * @brief 
 * 
 *          Tag:[Used in Encryption][Used in Decryption]
            Transformation proposed in the GOST Specification with Mapping Domain : V(8) ->V(8) 
            Apply nabla(_map[iter]*delta(x))
            Parameter:
                x: input to transform
            Returns:
                LinearTransformation(x(15)||...||x(0))
 * 
 * @param res 
 * @param x 
 */

void linear_Transformation(mpz_t res,mpz_t x){
    
    int _map_[]={
        1, 148, 32, 133, 16, 194, 192, 1, 251, 1, 192, 194, 16, 133, 32, 148
    };
    
    mpz_t _tmp_shift_8,_tmp_mask,_tmp_8_and,m_res,V_8_Field,_mod_res,_m,_x,_res;
    
    mpz_init(_x);
    mpz_init(_res);
    mpz_set(_x,x);
    mpz_set_ui(_res,0);
    mpz_init(_m);
    mpz_init(_tmp_shift_8);
    mpz_init(_tmp_mask);
    mpz_init(_tmp_8_and);
    mpz_init(m_res);
    mpz_init(V_8_Field);
    mpz_init(_mod_res);
    mpz_set_str(V_8_Field,"111000011",2);
    mpz_set_str(_tmp_mask,"ff",16);
    #pragma omp for
    for (int i=15;i>=0;i--){
        mpz_tdiv_q_2exp(_tmp_shift_8,_x,8*i);
        mpz_and(_tmp_8_and,_tmp_shift_8,_tmp_mask);
        mpz_set_ui(_m,_map_[i]);
        Multiply_Poly_V_128(m_res,_m,_tmp_8_and);
        Mod_Poly_Reduction(_mod_res,m_res,V_8_Field);
        mpz_xor(_res,_res,_mod_res);
        
    }
    
    mpz_set(res,_res);
    mpz_clear(_tmp_shift_8);
    mpz_clear(_x);
    mpz_clear(_res);
    mpz_clear(_tmp_mask);
    mpz_clear(_tmp_8_and);
    mpz_clear(V_8_Field);
    mpz_clear(m_res);
    mpz_clear(_mod_res);
    mpz_clear(_m);

}


/**
 * @brief 
 *  
 *          Tag:[Used in Key Schedule]
            Utility Function Explicitly Written for sake of readablity .
            Computes the RoundConstant c by applying L_Transformation
            Parameters:
                round_no: Number {0...9}
            Returns:
                L_Transformation(round_no) -> 256 bit
 * 
 * @param res 
 * @param round_no 
 */


void Round_constant(mpz_t res,int round_no){
    mpz_t rno,result;
    mpz_init(rno);
    mpz_init(result);
    
    mpz_set_ui(rno,round_no);
    L_Transformation(result,rno);
    mpz_set(res,result);
    mpz_clear(result);
    mpz_clear(rno);
}



/**
 * @brief 
 *          Tag: [ Used in Encryption ]
            Another Native Function to Kuznechik cipher to Apply R_Transformation func 16 times with the same domain. 
            
            Parameters:
                x: 128 bit input for which R_Transformation function has to be applied
            
            Returns:
                R_Transformation(R_Transformation....(x)) iterated 16 times -> 128 bits 
 * 
 * @param res 
 * @param x 
 */

void L_Transformation(mpz_t res,mpz_t x){
    mpz_t tmp;
    mpz_init(tmp);
    mpz_set(tmp,x);
    #pragma omp for
    for (int i=0;i<16;i++){
        R_Transformation(tmp,tmp);
    }
    mpz_set(res,tmp);
    mpz_clear(tmp);

}

/**
 * @brief 
 *      
 *          Tag: [ Used in Decryption ]
            Native function that Applies the inverse of the L_Transformation by implicitly calling the R_Transformation_inverse function. Same domain Mapping.
            
            Parameters:
                x: 128 bit input for which R_Transformation_inverse function has to be applied
            Returns:
                (R_Transformation_inverse(R_Transformation_inverse(....(x))) iterated 16 times) -> 128 bits 
                
 * 
 * @param res 
 * @param x 
 */

void L_Transformation_inverse(mpz_t res,mpz_t x){
    mpz_t tmp;
    mpz_init(tmp);
    mpz_set(tmp,x);
    for (int i=0;i<16;i++){
        R_Transformation_inverse(tmp,tmp);

    }
    mpz_set(res,tmp);
    mpz_clear(tmp);

}

/**
 * @brief 
 *          Tag:[Used in Key Schedule]
            Native function for Key Generation or Key Schedule Generation . 
            If you notice Interstingly this cipher follows a pattern of Fiestel Network for Key Schedule.
            Parameters:
                Key1:256 bit keys (Apply Combinations of Transformations to this )
                Key2:256 bit keys  (Nothing done here . Just return the same key as is )
                Round_Constant: Passed implicitly from the Round_constant function defined.
            Returns: 
                Array(L(S(roundconst^k1)),k2)
 *       
 * 
 * @param round_const 
 * @param k1 
 * @param k2 
 * @return mpz_t* 
 */

mpz_t*  F_Transformation(mpz_t round_const,mpz_t k1,mpz_t k2){
    mpz_t * arr=(mpz_t*)malloc(sizeof(mpz_t)*2);

    mpz_t _c1_xor_k1_,_S_tmp_,_L_tmp,_LSX_xor_k2,_rc,_k1,_k2;
    mpz_init(arr[0]);
    mpz_init(arr[1]);
    mpz_init(_c1_xor_k1_);
    mpz_init(_S_tmp_);
    mpz_init(_rc);
    mpz_init(_k1);
    mpz_init(_k2);

    mpz_init(_L_tmp);
    mpz_init(_LSX_xor_k2);
    mpz_set(_rc,round_const);
    mpz_set(_k1,k1);
    mpz_set(_k2,k2);

    mpz_xor(_c1_xor_k1_,_rc,_k1);
    S_Transformation(_S_tmp_,_c1_xor_k1_);
    L_Transformation(_L_tmp,_S_tmp_);
    mpz_xor(_LSX_xor_k2,_L_tmp,_k2);
    mpz_set(arr[0],_LSX_xor_k2);
    mpz_set(arr[1],_k1);
    mpz_clear(_rc);
    mpz_clear(_k1);
    mpz_clear(_k2);
    mpz_clear(_c1_xor_k1_);
    mpz_clear(_S_tmp_);
    mpz_clear(_L_tmp);
    mpz_clear(_LSX_xor_k2);

    return arr;
}


/**
 * @brief 
 * 
 *          This is the Function to perform Key Deployment from the initial key.
            This Key deployment algorithm uses Fiestel system to Get Separate Keys for each Round/iteration.
            initial keys:k>>128,k&mask_32
            Each set of keys obtained from each iteration are applied the F_Transformation.
            Every 8th iteration keys thus obtained is added to key_list.

            Parameters:
                Key:256 Pseudorandomly generated Key 
            Returns: 
                KeySchedule Array of Size 10
 * 
 * @param key 
 * @return mpz_t* 
 */

mpz_t* Key_Schedule(mpz_t key){
    printf("IN KEY_SCHED");
    mpz_t * key_arr=malloc(sizeof(mpz_t)*10);
    

    mpz_t k1,k2,mask,_shr_128,_and_mask,rnd_const,tmp1,tmp2,_key;
    for(int i=0;i<10;i++){
        mpz_init(key_arr[i]);
    }
    mpz_init(k1);
    mpz_init(k2);
    mpz_init(_key);
    mpz_init(tmp2);
    mpz_init(mask);
    mpz_init(tmp1);
    mpz_init(rnd_const);
    mpz_init(_shr_128);
    mpz_init(_and_mask);
    mpz_set(_key,key);
    mpz_set_str(mask,mask_128,16);
    mpz_tdiv_q_2exp(_shr_128,_key,128);
    mpz_and(_and_mask,_shr_128,mask);
    mpz_set(k1,_and_mask);
    mpz_and(_and_mask,_key,mask);
    mpz_set(k2,_and_mask);    
    int k_idx=0;
    mpz_set(key_arr[k_idx++],k1);
    mpz_set(key_arr[k_idx++],k2);
    mpz_t* arr;
    arr=malloc(sizeof(mpz_t)*2);
    mpz_init(arr[0]);
    mpz_init(arr[1]);
    
    
    for (int i=1;i<=32;i++){
        Round_constant(rnd_const,i);
        
        arr=F_Transformation(rnd_const,k1,k2);
        
        mpz_set(k1,arr[0]);
    
        mpz_set(k2,arr[1]);
        
        if(i%8==0){
            mpz_set(key_arr[k_idx++],k1);
            mpz_set(key_arr[k_idx++],k2);
        }
    }
    
   
    mpz_clear(k1);
    mpz_clear(k2);
    mpz_clear(arr[0]);
    mpz_clear(arr[1]);
    mpz_clear(_key);
    mpz_clear(tmp1);
    mpz_clear(tmp2);
    mpz_clear(mask);
    mpz_clear(rnd_const);
    mpz_clear(_shr_128);
    mpz_clear(_and_mask);
    
    return key_arr;
}

/**
 * @brief 
 * 
 *          Function To Encrypt Bloc Using Kuznechik Cipher .
            Uses all the function marked as [Used in Encryption] tag in the docstring.
            Parameters:
                None
                Implicitly uses the KeySchedule array for each round and apply L_Transformation(S(round_key^msg))
            Returns:
                128 bit Encrypted Cipher block
 * 
 * @param res 
 * @param message 
 * @param key 
 */

void encrypt(mpz_t res,mpz_t message,mpz_t key,mpz_t*key_arr){
    mpz_t * key_arr_=malloc(sizeof(mpz_t)*10);
    mpz_t msg,_xor,_Sx_,_lsx_,_key,_res;
    for(int i=0;i<10;i++){
        mpz_init(key_arr_[i]);
    }
    key_arr_=key_arr;
    mpz_init(_xor);
    mpz_init(_Sx_);
    mpz_init(_res);
    mpz_init(_lsx_);
    mpz_init(_key);
    mpz_init(msg);
    mpz_set(msg,message);

    mpz_set(_key,key);
    //key_arr_=Key_Schedule(_key);
    key_arr_=key_arr;
    //gmp_printf("ms: %Zx\n", _lsx_);
    #pragma omp for
    for (int i=0;i<9;i++){
        mpz_xor(_xor,key_arr_[i],msg);
        
        S_Transformation(_Sx_,_xor);
        
        L_Transformation(_lsx_,_Sx_);
        mpz_set(msg,_lsx_);
        //gmp_printf("keyarr: %Zx\n",msg );
    }
    
    mpz_xor(_res,msg,key_arr_[9]);
    mpz_set(res,_res);
    
    mpz_clear(_res);
    mpz_clear(_xor);
    mpz_clear(_key);
    mpz_clear(_Sx_);
    mpz_clear(_lsx_);
    mpz_clear(msg);
}


/**
 * @brief 
 *          Function To Decrypt Block Using Kuznechik Cipher .
            Uses all the function marked as [Used in Decryption] tag in the docstring.
            Parameters:
                None
                Implicitly uses the KeySchedule array for each round and apply (S_inv(L_Transformation_inverse(round_key^cipher)))
            Returns:
                128 bit Decrypted Cipher block
 * 
 * @param res 
 * @param cipher 
 * @param key 
 */
void decrypt(mpz_t res,mpz_t cipher,mpz_t key){
    mpz_t * key_arr_=malloc(sizeof(mpz_t)*10);
    mpz_t msg,_xor,_Sx_,_lsx_,_key,_res;
    for(int i=0;i<10;i++){
        mpz_init(key_arr_[i]);
    }
    mpz_init(_xor);
    mpz_init(_Sx_);
    mpz_init(_res);
    mpz_init(_lsx_);
    mpz_init(_key);
    mpz_init(msg);
    mpz_set(msg,cipher);

    mpz_set(_key,key);
    key_arr_=Key_Schedule(_key);
    #pragma omp for
    for (int i=9;i>0;i--){
         mpz_xor(_xor,key_arr_[i],msg);
         L_Transformation_inverse(_lsx_,_xor);
         S_Inv_Transformation(_Sx_,_lsx_);
         mpz_set(msg,_Sx_);



    }
    mpz_xor(_res,msg,key_arr_[0]);
    mpz_set(res,_res);
    
    mpz_clear(_res);
    mpz_clear(_xor);
    mpz_clear(_key);
    mpz_clear(_Sx_);
    mpz_clear(_lsx_);
    mpz_clear(msg);


}
/*
Code testing will create unit test and remove this in future version.
*/

int main(){
//printf("%lx",S_Transformation(0xffeeddccbbaa99881122334455667700)>>32);

mpz_t test,msg,res,key,cipher,x,m;
mpz_init(test);
mpz_init(cipher);
mpz_init(res);
mpz_init(key);
mpz_init(x);
mpz_init(m);
 mpz_t * key_arr_=malloc(sizeof(mpz_t)*10);
 for(int i=0;i<10;i++){
        mpz_init(key_arr_[i]);
    }


//mpz_set_str(x,"10101",2);
//mpz_set_str(m,"1100",2);
mpz_init(msg);
mpz_set_str(key,"8899aabbccddeeff0011223344556677fedcba98765432100123456789abcdef",16);
mpz_set_str(msg,"1122334455667700ffeeddccbbaa9988",16);
key_arr_=Key_Schedule(key);
//Round_constant(res,5);
gmp_printf("Original PlainText Message: %Zx\n", msg);
gmp_printf("Symmetric Key : %Zx\n", key);
//mpz_set_ui(res,10);
//mpz_set_str(test,"f9eae5f29b2815e31f11ac5d9c29fb01",16);
struct timeval start,end;
gettimeofday(&start,NULL);
///#pragma omp parallel
#pragma omp for
for(int i=0;i<10000;i++){
encrypt(cipher,msg,key,key_arr_);}

//encrypt(cipher,msg,key,key_arr_);
//encrypt(cipher,msg,key,key_arr_);
//gmp_printf("Cipher Text: %Zx\n", cipher);
gettimeofday(&end,NULL);
long sec=(end.tv_sec-start.tv_sec);
long us=(((sec*1000000)+end.tv_usec)-(start.tv_usec));
printf("\nExecutionTime: %lf ms\n",(double)us/1000);
decrypt(res,cipher,key);
gmp_printf("Decrypted Text: %Zx\n", res);
//R_Transformation_inverse(res,test);
//Key_Schedule(key);
//L_Transformation(res,test);
//(x^4 + x^2 + 1) * (x^3 + x^2)
//(x^7 + ... + x^2) mod (x^5+x)
//Mod_Poly_Reduction(res,x,m);
//Round_constant(res,1);
//printf("helo%d\n",*(p(12,45)+1));
//F_Transformation(res,msg,test);
//gmp_printf("Val: %Zx\n",F_Transformation(x,key,msg)[1]);
//Multiply_Poly_V_128(res,x,m);
//S_Transformation(res,test);
//S_Inv_Transformation(res,res);
//Multiply_Poly_V_128(res,test,test);
//gmp_printf("Valres: %Zx\n", res);
mpz_clear(test);
mpz_clear(cipher);
mpz_clear(res);
mpz_clear(key);
mpz_clear(x);
mpz_clear(m);


}