crypto_project.c

  /*** Deep Shah ***/
/// Crypto Project ///


#include<stdio.h>
#include<stdint.h>
#include<math.h>
#define lli long long int
#define BYTES uint8_t

void subBytes(BYTES state[][4]);
void invSubBytes(BYTES state[][4]);
void shiftRows(BYTES state[][4]);
void invShiftRows(BYTES state[][4]);
BYTES Mul_GF(BYTES a, BYTES b);
void mix_columns(BYTES state[][4]);
void inv_mix_columns(BYTES state[][4]);
void addRoundKey(BYTES state[][4], BYTES key[][4]);
void keyExpansion(BYTES key[][4], BYTES keyExp[11][4][4]);
lli power(lli a, lli b, lli P);
void print(BYTES txt[4][4]);
BYTES *AliceFunc(BYTES messageA[][4], lli ka);
BYTES *BobFunc(BYTES cipherA[][4], lli kb);
BYTES *calcMAC(BYTES MAC[][4], BYTES M[][4], BYTES K[][4]);
BYTES *encryptAES(BYTES message[][4], BYTES key[][4]);
BYTES *decryptAES(BYTES message[][4], BYTES key[][4]);
BYTES MAC_A[4][4], MAC_B[4][4];
int diffie_hellman_fun(unsigned int a1, unsigned int n);

P = 10007;
G = 5;



int main(){


	unsigned int Alicekey, Bobkey;

    fflush(stdin);
	printf("Key for Alice : ");
    scanf("%d", &Alicekey);

    fflush(stdin);
	printf("Key for Bob : ");
    scanf("%d", &Bobkey);

    int Alice_final = diffie_hellman_fun(5, Alicekey);
    int Bob_final = diffie_hellman_fun(5, Bobkey);

    int ka = diffie_hellman_fun(Alice_final, Bobkey);
    int kb = diffie_hellman_fun(Bob_final, Alicekey);


    printf("\nAlice Secret Key ka: %d\n", ka);
    printf("Bob Secret Key kb: %d\n", kb);
	if(ka!=kb){
        printf("Compilation error");
        return -1;
	}

    BYTES message[4][4];
	BYTES *cipher = AliceFunc(message, ka);
	printf("\n\nCipher A: \n");
    print(cipher);

    printf("\nMAC_A: \n");
    print(MAC_A);


	BYTES *decrypt = BobFunc(cipher,kb);
	printf("\n\nBob Message_B: \n");
    print(decrypt);

	printf("\n");


	printf("\nMAC_B: \n");
    print(MAC_B);

	printf("\n");

    return 0;

}


BYTES *AliceFunc(BYTES messageA[][4], lli ka){

    BYTES keyA[4][4];
    BYTES key_[16];

    int v=0;
    while(v<16){
        key_[v]=(ka&0xff);
        ka = ka>>8;
        v++;
    }

    for(int i=0, k=15;i<4;i++) {
		for(int j=0;j<4;j++) {
            keyA[j][i] = key_[k];
            k--;
        }
	}

    printf("\nEnter Initial Message_A: \n");

    BYTES message_[4][4];
    fflush(stdin);
	for(int i=0;i<4;i++) {
		for(int j=0;j<4;j++) {
            scanf("%x",&message_[i][j]);
            messageA[j][i] = message_[i][j];
        }
	}

	calcMAC(MAC_A, messageA, keyA);

    BYTES *cipher = encryptAES(messageA,keyA);

	return cipher;
}


BYTES *BobFunc(BYTES cipherA[][4], lli kb){

    BYTES keyB[4][4], keyB2[4][4], key_[16];

    int v=0;
    while(v<16){
        key_[v]=(kb&0xff);
        kb = kb>>8;
        v++;
    }

	for(int i=0, k=15;i<4;i++) {
		for(int j=0;j<4;j++) {
            keyB[j][i] = key_[k];
            keyB2[j][i] = key_[k];
            k--;
        }
	}

    BYTES *messageB = decryptAES(cipherA,keyB);
    calcMAC(MAC_B, messageB, keyB2);
	return messageB;
}

int diffie_hellman_fun(unsigned int a1, unsigned int n)
{
    int t_0 = 1;
    while (n > 0)
    {
        if ((n & 1) != 0)
        {
            t_0 = t_0 * a1;
            t_0 = t_0 % P;
        }
        a1 = a1 * a1;
        a1 = a1 % P;
        n = n >> 1;
    }
    return t_0;
}



BYTES *calcMAC(BYTES MAC[][4], BYTES M[][4], BYTES K[][4]){
    for(int i=0;i<4;i++) {
		for(int j=0;j<4;j++) {
            MAC[i][j] = M[i][j] ^ K[i][j];
        }
	}
}



BYTES sBox[256] = {
        0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
        0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
        0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
        0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
        0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
        0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
        0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
        0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
        0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
        0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
        0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
        0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
        0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
        0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
        0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
        0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
};

BYTES inv_sBox[256] = {
        0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
        0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
        0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
        0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
        0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
        0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
        0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
        0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
        0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
        0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
        0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
        0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
        0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
        0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
        0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
        0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
};


BYTES Rcon[4][10] = {
	0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0x1b,0x36,
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
};



BYTES *encryptAES(BYTES message[][4], BYTES key[][4]){
    BYTES keyExp[11][4][4];
    keyExpansion(key, keyExp);
	addRoundKey(message, keyExp[0]);

	for(int i=0; i<9; i++) {
		subBytes(message);
		shiftRows(message);
		mix_columns(message);
		addRoundKey(message, keyExp[i+1]);
	}

	subBytes(message);
	shiftRows(message);
	addRoundKey(message, keyExp[10]);

	return message;
}

BYTES *decryptAES(BYTES message[][4], BYTES key[][4]){
    BYTES keyExp[11][4][4];
    keyExpansion(key, keyExp);
	addRoundKey(message, keyExp[10]);

	for(int i=9; i>0; i--) {
        invShiftRows(message);
		invSubBytes(message);
		addRoundKey(message, keyExp[i]);
		inv_mix_columns(message);
	}
	invShiftRows(message);
	invSubBytes(message);
	addRoundKey(message, keyExp[0]);

	return message;
}

void print(BYTES txt[4][4])
{
    for(int i=0;i<4;i++) {
		for(int j=0;j<4;j++) {
            printf("%x",txt[j][i]);
        }
	}
	printf("\n");
}

void subBytes(BYTES state[][4])
{
    int i,j;
    for(i=0;i<4;i++) {
		for(j=0;j<4;j++) {
            state[i][j]=sBox[state[i][j]];
        }
	}
}

void invSubBytes(BYTES state[][4])
{
    int i,j;
    for(i=0;i<4;i++) {
		for(j=0;j<4;j++) {
            state[i][j]=inv_sBox[state[i][j]];
        }
	}
}


void shiftRows(BYTES state[][4])
{
	int i,j;
	BYTES mtx[4];
	for(i=1;i<4;i++) {
		for(j=0;j<4;j++) {
			mtx[j]=state[i][j];
		}

		for(j=0;j<4;j++) {
			state[i][j]=mtx[(j+i)%4];
		}
	}
}

void invShiftRows(BYTES state[][4])
{
	int i,j;
	BYTES mtx[4];
	for(i=1;i<4;i++) {
		for(j=0;j<4;j++) {
			mtx[j]=state[i][j];
		}

		for(j=0;j<4;j++) {
			state[i][j]=mtx[(4-i+j)%4];
		}
	}
}


BYTES Mul_GF(BYTES a, BYTES b)
{
	BYTES p = 0, i, c;

	for (i = 0; i < 8; i++) {
		if (b & 1) p ^= a;
		c = a & 0x80;
		a <<= 1;
		if (c) a ^= 0x1B;
		b >>= 1;
	}

	return p;
}

void mix_columns(BYTES state[][4])
{
    int i,j;
	BYTES mtx[4];
	for(j=0;j<4;j++) {
		for(i=0;i<4;i++) {
			mtx[i]=state[i][j];
		}
		for(i=0;i<4;i++) {
			state[i][j] = Mul_GF(0x02,mtx[i])^Mul_GF(0x03,mtx[(1+i)%4])^Mul_GF(0x01,mtx[(2+i)%4])^Mul_GF(0x01,mtx[(3+i)%4]); // Taking Sum
		}
	}
}

void inv_mix_columns(BYTES state[][4])
{
    int i,j;
	BYTES mtx[4];
	for(j=0;j<4;j++) {
		for(i=0;i<4;i++) {
			mtx[i]=state[i][j];
		}
		for(i=0;i<4;i++) {
			state[i][j] = Mul_GF(0x0e,mtx[i])^Mul_GF(0x0b,mtx[(1+i)%4])^Mul_GF(0x0d,mtx[(2+i)%4])^Mul_GF(0x09,mtx[(3+i)%4]); // Taking Sum
		}
	}
}

void addRoundKey(BYTES state[][4], BYTES key[][4])
{
	int i,j;

	for(j=0;j<4;j++) {
		for(i=0;i<4;i++) {
			state[i][j]=state[i][j]^key[i][j];
		}
	}
}

void keyExpansion(BYTES key[][4], BYTES keyExp[11][4][4])
{
    for(int k=0; k<11; k++){
        int i,j;
        for(i=0;i<4;i++) {
            for(j=0;j<4;j++) {
                keyExp[k][i][j]=key[i][j];
            }
        }

        BYTES mtx[4];
        for(i=0;i<4;i++) {
            mtx[i]=key[(i+1)%4][3];
        }

        for(i=0;i<4;i++) {
            mtx[i]=sBox[mtx[i]];
        }

        for(i=0;i<4;i++) {
            key[i][0]=key[i][0]^mtx[i]^Rcon[i][k];
        }

        for(j=1;j<4;j++) {
            for(i=0;i<4;i++) {
                key[i][j]=key[i][j]^key[i][j-1];
            }
        }
    }
}