-
Notifications
You must be signed in to change notification settings - Fork 0
/
AffineCipher.java
62 lines (56 loc) · 1.04 KB
/
AffineCipher.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
/*Author Name - Tushar Vidhani
* Registration No. - 2241022011
* Section - 32
*/
import java.util.Scanner;
public class AffineCipher
{
public static String encrypt(String plaintext)
{
int k1=7,k2=2;
String C="";
for(int i=0;i<plaintext.length();i++)
{
int P=plaintext.charAt(i);
P=P-'a';
C=C+(char)((P*k1+k2)%26+'A');
}
return C;
}
public static String decrypt(String ciphertext)
{
int k1=7,k2=2,k1_inverse=0;
String P="";
for(int j=1;j<26;j++)
{
if(k1*j%26==1)
{
k1_inverse=j;
break;
}
}
for(int i=0;i<ciphertext.length();i++)
{
int C=ciphertext.charAt(i);
C=C-'A';
if (C-k2<0)
while(true)
{
C=C+26;
if (C>=0)
break;
}
P=P+(char)((C-k2)*k1_inverse%26+'a');
}
return P;
}
public static void main(String[] args)
{
Scanner sc=new Scanner(System.in);
System.out.print("Enter the plaintext: ");
String plaintext=sc.next();
String C=encrypt(plaintext);
System.out.println("Ciphertext: "+C);
System.out.println("Decrypted text: "+decrypt(C));
}
}