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Sr. No. Practical Name Signature

1 Write a program to implement Ceaser cipher in C.

2 Write a program to implement monoalphabetic cipher in C.

3 Write a program to implement playfair cipher in C.

4 Write a program to implement Hill cipher in C.

5 Write a program to implement railfence cipher in C.

6 Write a program to implement columner cipher in C.

7 Write a program to implement RSA in C.

INTERNET SECURITY

>>INDEX

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Practical No. 1

AIM:- Write a program to implement Ceaser

cipher in C.

#include

#include

#include

void main()

{

int i,j,shift,k,temp;

char pt[100],ency[100];

char value(int); clrscr();

printf("Please Enter The PlainText=\n");

gets(pt);printf("Please Enter The shift value=\n");

scanf("%d",&shift);

printf("\n \n The Encrypted Text is=\n");

for (i=0;i

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else

{

if (ency[i]=='.')

{

printf("%c",pt[i]);

}else

{

temp=ency[i]-shift;

printf("%c",temp);

}

}

}

ency[i]='\0';

getch();

}

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Output:

Pleas Enter the Planitext=

Milan

Pleas Enter The Shift Value=

2

The Encrypted text is=

Oknco

The Decrypted Text is=

milan

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Practical No. 2

AIM:-Write a program to implement MONOALPHABETIC cipher in C.

#include

#include#include

void main()

{

int i,length,temp;

char a[100],encrypt[100],decrypt[100];

char cipher(char,int);

clrscr();

printf("Enter The PlainText=\n");

gets(a);length=strlen(a);

temp=0;

printf("The Encrypted Message=\n");

for (i=0;i

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case 'd':

return ('e');

case 'e':

return ('f');

case 'f':

return ('g');

case 'g':

return ('h');

case 'h':

return ('i');

case 'i':

return ('j');

case 'j':

return ('k');

case 'k':

return ('l');

case 'l':

return('m');case 'm':

return ('n');

case 'n':

return ('o');

case 'o':

return ('p');

case 'p':

return ('q');

case 'q':

return ('r');

case 'r':return ('s');

case 's':

return ('t');

case 't':

return ('u');

case 'u':

return ('v');

case 'v':

return (w');

case 'w':

return ('x');case 'x':

return ('y');

case 'y':

return ('z');

case 'z':

return ('a');

}

}}

else{return(' '); }

}

}

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Output:

Enter The Plaintext=

Milan

The Encrypted Message=

njmbo

The Decrypted Message=

milan

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Practical No. 3

AIM:-Write a program to implement Playfair cipher in C.

#include

#include

#include

void main()

{

char key[10],a[5][5],pt[100],ct[100];

int row=0,col=0,x,y,i,j,flag=0;

clrscr();

printf(" enter key\n ");

gets(key);

for(i=0;i

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if(key[j]==i+97)

{

flag=0;

}

}

if(flag==1 && i!=9)

{

a[row][col]=i+97;

printf(" %c",a[row][col]); col++;

if(col==5)

{

row=row+1;

col=0;

printf("\n");

}

}

}

printf("\n ");

printf("enter the plaintext:"); gets(pt);

j=1;

for(i=0;i

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{

r1=p;

c1=q;

}

if(a[p][q]==y)

{

r2=p;

c2=q;

}

}

}

if(r1==r2)

{

ct[i]=a[r1][(c1+1)%5]; ct[j]=a[r2][(c2+1)%5];

printf("%c%c",ct[i],ct[j]);

}

else if(c1==c2)

{

ct[i]=a[(r1+1)%5][c1];

ct[j]=a[(r2+1)%5][c2];

printf("%c%c",ct[i],ct[j]);

}

else

{

ct[i]=a[r1][c2];

ct[j]=a[r2][c1];

printf("%c%c",ct[i],ct[j]);

}

i+=2;

j+=2;

}

getch();

}

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Output:

Enter Key:

Monkey

M o n k e

y a b c d

f g h i/j l

p q r s t

u v w x z

Enter The Plaintext : Milan

kfgd

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Practical No.4

AIM:-Write a program to implement HILL CIPHER in C.

#include

#include void main()

{

chars[26]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};char p[100],ency[100],decy[100];

int

i,j,a[10][10]={{6,24,1},{13,16,10},{20,17,15}},length,num[100],c[100],b[10][10]={{8,5,10},{21,8,21},{21,12,8}}; clrscr();

printf(" The Key is=\n"); for (i=0;i

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26]; ency[i]='\0';

puts(ency);

printf(" The Inverse Key

is=\n "); for (i=0;i

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Output:

The Key is=

6 24 1

13 16 10

20 17 17

Enter The Plaintext=

Milan

The encrypted Message is=

Vep

The Inverse Key is=

8 5 10

21 8 21

21 12 8

The Decrypted Message is=

milan

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Practical No.5

AIM:-Write a program to implement RAILFENCE cipher in C.

#include

#include

#include

void main()

{

int i,length,j,k,l,len1,len2,temp1,temp2,q;

char a[100],text1[100],text2[100],

encrypt[100],decrypttext1[100],decrypttext2[100],decrypt[100]

clrscr();

printf("Enter The PlainText=\n");

gets(a);

length=strlen(a); j=0;

k=0;

for (i=0;i

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len1=i;

for (l=0;l

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Output:

Enter the plaintext=

Milan

The encrypted message is=

Mlnia

Decrypted message is=

milan

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Practical No.6

AIM:-Write a program to implement COLUMNER cipher in C.

#include

#include

#include

void main()

{

char a[100],b[100][100]={' '},ency[100]={' '},decy[100][100]={' '},temp[100][100]={' '};

int pattern[10]={7,0,9,5,1,6,3,4,2,8};

int length,i,j,k,l,m,condi,distance,p,length12,l1,l2;

clrscr();

printf("Enter The Message=\n");

gets(a);length=strlen(a); condi=length;

k=0;

l1=0;

l2=0;

printf("The Encryption Message is=\n");

if (length%10==0)

{

for (i=0;i

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distance=distance+length;

for (i=length;i

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Output:

Enter the message=

Milan

The encryption message is=Xmxxixanlx

The decryption message is=

milan

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Practical No.7

AIM:-Write a program to implement RSA in C.

#include

#include

void main()

{

int p,q,n,e,i;

int temp,temp1,d,pt,c,m;

clrscr();

printf("Enter The first Prime number=\n"); scanf("%d",&p);

printf("Enter The second Prime number=\n"); scanf("%d",&q);

n=p*q; q=(p-1)*(q-1); e=2;

while (e>1)

{

if (q%e!=0)

goto end;

else

e++;

}

end :

d=1;

temp=e-2;d=((temp*q)+1)/e;

last:

printf("\n%d",d);

printf("\nThe Public Key is e={%d} and n={%d}\n",e,n);

printf("The Private Key is d={%d} and n={%d}\n",d,n);

printf("Enter The Plain Text=\n");

scanf("%d",&pt);

c=1;

printf("The cipher text is=\n");

for (i=0;i

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Output:

Enter the first prime number=

13

Enter the second prime number=

17

115

The public key is e={5} and n={221}

The private key is d={115} and n={221}

Enter the plain text=

Milan

The cipher text is=

138

The decrypted text is=

115