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Update some classes in Ciphers package

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This commit is contained in:
yanglbme 2021-10-29 10:27:12 +08:00
parent 7858187d59
commit b159835878
11 changed files with 1269 additions and 1380 deletions
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4
Ciphers/AES.java
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@ -55,7 +55,9 @@ public class AES {
0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16 0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
}; };
/** Inverse Rijndael S-box Substitution table used for decryption in the subBytesDec step. */ /**
* Inverse Rijndael S-box Substitution table used for decryption in the subBytesDec step.
*/
private static final int[] INVERSE_SBOX = { private static final int[] INVERSE_SBOX = {
0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB, 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, 0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,

8
Ciphers/AESEncryption.java
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@ -1,13 +1,8 @@
package Ciphers; package Ciphers;
import javax.crypto.*;
import java.security.InvalidKeyException; import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException; import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
/** /**
* This example program shows how AES encryption and decryption can be done in Java. Please note * This example program shows how AES encryption and decryption can be done in Java. Please note
@ -17,6 +12,7 @@ import javax.crypto.SecretKey;
public class AESEncryption { public class AESEncryption {
private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray(); private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
/** /**
* 1. Generate a plain text for encryption 2. Get a secret key (printed in hexadecimal form). In * 1. Generate a plain text for encryption 2. Get a secret key (printed in hexadecimal form). In
* actual use this must by encrypted and kept safe. The same key is required for decryption. * actual use this must by encrypted and kept safe. The same key is required for decryption.

67
Ciphers/AffineCipher.java
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@ -1,36 +1,23 @@
//The ‘key’ for the Affine cipher consists of 2 numbers, we’ll call them a and b.
// The following discussion assumes the use of a 26 character alphabet (m = 26).
// a should be chosen to be relatively prime to m (i.e. a should have no factors in common with m).
package Ciphers; package Ciphers;
import java.util.Scanner; class AffineCipher {
class AffineCipher // Key values of a and b
{ static int a = 17;
static Scanner in = new Scanner(System.in); static int b = 20;
static String encryptMessage(char[] msg) static String encryptMessage(char[] msg) {
{ /// Cipher Text initially empty
System.out.println("Enter key value a for encryption : ");
int a = in.nextInt();
System.out.println("Enter key value b for encryption : ");
int b = in.nextInt();
/// Initially empty cipher String
String cipher = ""; String cipher = "";
for (int i = 0; i < msg.length; i++) for (int i = 0; i < msg.length; i++) {
{
// Avoid space to be encrypted // Avoid space to be encrypted
/* applying encryption formula ( a x + b ) mod m /* applying encryption formula ( a x + b ) mod m
{here x is msg[i] and m is 26} and added 'A' to {here x is msg[i] and m is 26} and added 'A' to
bring it in range of ascii alphabet[ 65-90 | A-Z ] */ bring it in range of ascii alphabet[ 65-90 | A-Z ] */
if (msg[i] != ' ') if (msg[i] != ' ') {
{
cipher = cipher cipher = cipher
+ (char) ((((a * (msg[i] - 'A')) + b) % 26) + 'A'); + (char) ((((a * (msg[i] - 'A')) + b) % 26) + 'A');
} else // append space character } else // else simply append space character
{ {
cipher += msg[i]; cipher += msg[i];
} }
@ -38,42 +25,30 @@ class AffineCipher
return cipher; return cipher;
} }
static String decryptCipher(String cipher) static String decryptCipher(String cipher) {
{
System.out.println("Enter key value a for decryption : ");
int a = in.nextInt();
System.out.println("Enter key value b for decryption : ");
int b = in.nextInt();
String msg = ""; String msg = "";
int a_inv = 0; int a_inv = 0;
int flag = 0; int flag = 0;
//Find a^-1 (the multiplicative inverse of a //Find a^-1 (the multiplicative inverse of a
//in the group of integers modulo m.) //in the group of integers modulo m.)
for (int i = 0; i < 26; i++) for (int i = 0; i < 26; i++) {
{
flag = (a * i) % 26; flag = (a * i) % 26;
// Check if (a*i)%26 == 1, // Check if (a*i)%26 == 1,
// if so, then i will be the multiplicative inverse of a // then i will be the multiplicative inverse of a
if (flag == 1) if (flag == 1) {
{
a_inv = i; a_inv = i;
} }
} }
for (int i = 0; i < cipher.length(); i++) for (int i = 0; i < cipher.length(); i++) {
{
/*Applying decryption formula a^-1 ( x - b ) mod m /*Applying decryption formula a^-1 ( x - b ) mod m
{here x is cipher[i] and m is 26} and added 'A' {here x is cipher[i] and m is 26} and added 'A'
to bring it in range of ASCII alphabet[ 65-90 | A-Z ] */ to bring it in range of ASCII alphabet[ 65-90 | A-Z ] */
if (cipher.charAt(i) != ' ') if (cipher.charAt(i) != ' ') {
{
msg = msg + (char) (((a_inv * msg = msg + (char) (((a_inv *
((cipher.charAt(i) + 'A' - b)) % 26)) + 'A'); ((cipher.charAt(i) + 'A' - b)) % 26)) + 'A');
} } else //else simply append space character
else // append space character
{ {
msg += cipher.charAt(i); msg += cipher.charAt(i);
} }
@ -82,17 +57,17 @@ class AffineCipher
return msg; return msg;
} }
// Main method // Driver code
public static void main(String[] args) public static void main(String[] args) {
{
String msg = "AFFINE CIPHER"; String msg = "AFFINE CIPHER";
// Encrypting message // Calling encryption function
String cipherText = encryptMessage(msg.toCharArray()); String cipherText = encryptMessage(msg.toCharArray());
System.out.println("Encrypted Message is : " + cipherText); System.out.println("Encrypted Message is : " + cipherText);
// Decrypting message // Calling Decryption function
System.out.println("Decrypted Message is: " + decryptCipher(cipherText)); System.out.println("Decrypted Message is: " + decryptCipher(cipherText));
} }
} }

4
Ciphers/ColumnarTranspositionCipher.java
View File

@ -114,7 +114,9 @@ public class ColumnarTranspositionCipher {
} }
} }
/** @return charValues */ /**
* @return charValues
*/
private static Object[] findElements() { private static Object[] findElements() {
Object[] charValues = new Object[keyword.length()]; Object[] charValues = new Object[keyword.length()];
for (int i = 0; i < charValues.length; i++) { for (int i = 0; i < charValues.length; i++) {

157
Ciphers/HillCipher.java
View File

@ -1,169 +1,162 @@
package Ciphers; package Ciphers;
import java.util.*; import java.util.Scanner;
/* /*
* Java Implementation of Hill Cipher * Java Implementation of Hill Cipher
* Hill cipher is a polyalphabetic substitution cipher. Each letter is represented by a number belonging to the set Z26 where A=0 , B=1, ..... Z=25. * Hill cipher is a polyalphabetic substitution cipher. Each letter is represented by a number belonging to the set Z26 where A=0 , B=1, ..... Z=25.
* To encrypt a message, each block of n letters (since matrix size is n x n) is multiplied by an invertible n × n matrix, against modulus 26. * To encrypt a message, each block of n letters (since matrix size is n x n) is multiplied by an invertible n × n matrix, against modulus 26.
* To decrypt the message, each block is multiplied by the inverse of the matrix used for encryption. * To decrypt the message, each block is multiplied by the inverse of the matrix used for encryption.
* The cipher key and plaintext/ciphertext are user inputs. * The cipher key and plaintext/ciphertext are user inputs.
* @author Ojasva Jain * @author Ojasva Jain
*/ */
public class HillCipher{ public class HillCipher {
static Scanner in = new Scanner (System.in); static Scanner in = new Scanner(System.in);
/* Following function encrypts the message /* Following function encrypts the message
*/ */
static void encrypt(String message) static void encrypt(String message) {
{
message = message.toUpperCase(); message = message.toUpperCase();
// Get key matrix // Get key matrix
System.out.println("Enter key matrix size"); System.out.println("Enter key matrix size");
int n = in.nextInt(); int n = in.nextInt();
System.out.println("Enter Key/encryptionKey matrix "); System.out.println("Enter Key/encryptionKey matrix ");
int keyMatrix[][] = new int [n][n]; int keyMatrix[][] = new int[n][n];
for(int i=0;i<n;i++){ for (int i = 0; i < n; i++) {
for(int j=0;j<n;j++){ for (int j = 0; j < n; j++) {
keyMatrix[i][j] = in.nextInt(); keyMatrix[i][j] = in.nextInt();
} }
} }
//check if det = 0 //check if det = 0
if(determinant(keyMatrix,n)%26 == 0) if (determinant(keyMatrix, n) % 26 == 0) {
{
System.out.println("Invalid key, as determinant = 0. Program Terminated"); System.out.println("Invalid key, as determinant = 0. Program Terminated");
return; return;
} }
int [][]messageVector = new int[n][1]; int[][] messageVector = new int[n][1];
String CipherText=""; String CipherText = "";
int cipherMatrix [][] = new int [n][1]; int cipherMatrix[][] = new int[n][1];
int j = 0; int j = 0;
while(j<message.length()){ while (j < message.length()) {
for (int i = 0; i < n; i++){ for (int i = 0; i < n; i++) {
if(j>=message.length()){ messageVector[i][0] = 23;} if (j >= message.length()) {
else messageVector[i][0] = 23;
messageVector[i][0] = (message.charAt(j))%65; } else
messageVector[i][0] = (message.charAt(j)) % 65;
System.out.println(messageVector[i][0]); System.out.println(messageVector[i][0]);
j++; j++;
} }
int x, i; int x, i;
for (i = 0; i < n; i++) for (i = 0; i < n; i++) {
{
cipherMatrix[i][0] = 0; cipherMatrix[i][0] = 0;
for (x = 0; x < n; x++) for (x = 0; x < n; x++) {
{
cipherMatrix[i][0] += keyMatrix[i][x] * messageVector[x][0]; cipherMatrix[i][0] += keyMatrix[i][x] * messageVector[x][0];
} }
System.out.println(cipherMatrix[i][0]); System.out.println(cipherMatrix[i][0]);
cipherMatrix[i][0] = cipherMatrix[i][0] % 26; cipherMatrix[i][0] = cipherMatrix[i][0] % 26;
} }
for (i = 0; i < n; i++) for (i = 0; i < n; i++)
CipherText += (char)(cipherMatrix[i][0] + 65); CipherText += (char) (cipherMatrix[i][0] + 65);
} }
System.out.println("Ciphertext: "+ CipherText); System.out.println("Ciphertext: " + CipherText);
} }
//Following function decrypts a message
static void decrypt(String message) //Following function decrypts a message
{ static void decrypt(String message) {
message = message.toUpperCase(); message = message.toUpperCase();
// Get key matrix // Get key matrix
System.out.println("Enter key matrix size"); System.out.println("Enter key matrix size");
int n = in.nextInt(); int n = in.nextInt();
System.out.println("Enter inverseKey/decryptionKey matrix "); System.out.println("Enter inverseKey/decryptionKey matrix ");
int keyMatrix[][] = new int [n][n]; int keyMatrix[][] = new int[n][n];
for(int i=0;i<n;i++){ for (int i = 0; i < n; i++) {
for(int j=0;j<n;j++){ for (int j = 0; j < n; j++) {
keyMatrix[i][j] = in.nextInt(); keyMatrix[i][j] = in.nextInt();
} }
} }
//check if det = 0 //check if det = 0
if(determinant(keyMatrix,n)%26 == 0) if (determinant(keyMatrix, n) % 26 == 0) {
{
System.out.println("Invalid key, as determinant = 0. Program Terminated"); System.out.println("Invalid key, as determinant = 0. Program Terminated");
return; return;
} }
//solving for the required plaintext message //solving for the required plaintext message
int [][]messageVector = new int[n][1]; int[][] messageVector = new int[n][1];
String PlainText=""; String PlainText = "";
int plainMatrix [][] = new int [n][1]; int plainMatrix[][] = new int[n][1];
int j = 0; int j = 0;
while(j<message.length()){ while (j < message.length()) {
for (int i = 0; i < n; i++){ for (int i = 0; i < n; i++) {
if(j>=message.length()){ messageVector[i][0] = 23;} if (j >= message.length()) {
else messageVector[i][0] = 23;
messageVector[i][0] = (message.charAt(j))%65; } else
messageVector[i][0] = (message.charAt(j)) % 65;
System.out.println(messageVector[i][0]); System.out.println(messageVector[i][0]);
j++; j++;
} }
int x, i; int x, i;
for (i = 0; i < n; i++) for (i = 0; i < n; i++) {
{
plainMatrix[i][0] = 0; plainMatrix[i][0] = 0;
for (x = 0; x < n; x++) for (x = 0; x < n; x++) {
{
plainMatrix[i][0] += keyMatrix[i][x] * messageVector[x][0]; plainMatrix[i][0] += keyMatrix[i][x] * messageVector[x][0];
} }
plainMatrix[i][0] = plainMatrix[i][0] % 26; plainMatrix[i][0] = plainMatrix[i][0] % 26;
} }
for (i = 0; i < n; i++) for (i = 0; i < n; i++)
PlainText += (char)(plainMatrix[i][0] + 65); PlainText += (char) (plainMatrix[i][0] + 65);
}
System.out.println("Plaintext: " + PlainText);
} }
System.out.println("Plaintext: "+PlainText);
}
// Determinant calculator // Determinant calculator
public static int determinant(int a[][], int n){ public static int determinant(int a[][], int n) {
int det = 0, sign = 1, p = 0, q = 0; int det = 0, sign = 1, p = 0, q = 0;
if(n==1){ if (n == 1) {
det = a[0][0]; det = a[0][0];
} } else {
else{ int b[][] = new int[n - 1][n - 1];
int b[][] = new int[n-1][n-1]; for (int x = 0; x < n; x++) {
for(int x = 0 ; x < n ; x++){ p = 0;
p=0;q=0; q = 0;
for(int i = 1;i < n; i++){ for (int i = 1; i < n; i++) {
for(int j = 0; j < n;j++){ for (int j = 0; j < n; j++) {
if(j != x){ if (j != x) {
b[p][q++] = a[i][j]; b[p][q++] = a[i][j];
if(q % (n-1) == 0){ if (q % (n - 1) == 0) {
p++; p++;
q=0; q = 0;
} }
} }
} }
} }
det = det + a[0][x] *determinant(b, n-1) * sign; det = det + a[0][x] * determinant(b, n - 1) * sign;
sign = -sign; sign = -sign;
} }
} }
return det; return det;
} }
// Function to implement Hill Cipher // Function to implement Hill Cipher
static void hillcipher(String message) static void hillcipher(String message) {
{
message.toUpperCase(); message.toUpperCase();
System.out.println("What do you want to process from the message?"); System.out.println("What do you want to process from the message?");
System.out.println("Press 1: To Encrypt"); System.out.println("Press 1: To Encrypt");
System.out.println("Press 2: To Decrypt"); System.out.println("Press 2: To Decrypt");
short sc = in.nextShort(); short sc = in.nextShort();
if(sc == 1) if (sc == 1)
encrypt(message); encrypt(message);
else if(sc == 2) else if (sc == 2)
decrypt(message); decrypt(message);
else else
System.out.println("Invalid input, program terminated."); System.out.println("Invalid input, program terminated.");
} }
// Driver code // Driver code
public static void main(String[] args) public static void main(String[] args) {
{
// Get the message to be encrypted // Get the message to be encrypted
System.out.println("Enter message"); System.out.println("Enter message");
String message = in.nextLine(); String message = in.nextLine();

6
Ciphers/RSA.java
View File

@ -1,10 +1,12 @@
package Ciphers; package Ciphers;
import javax.swing.*;
import java.math.BigInteger; import java.math.BigInteger;
import java.security.SecureRandom; import java.security.SecureRandom;
import javax.swing.JOptionPane;
/** @author Nguyen Duy Tiep on 23-Oct-17. */ /**
* @author Nguyen Duy Tiep on 23-Oct-17.
*/
public final class RSA { public final class RSA {
public static void main(String[] args) { public static void main(String[] args) {

35
Ciphers/simpleSubCipher.java → Ciphers/SimpleSubCipher.java
View File

@ -1,18 +1,17 @@
package ciphers; package ciphers;
import java.util.*; import java.util.HashMap;
import java.util.Map;
/** /**
*
* The simple substitution cipher is a cipher that has been in use for many hundreds of years * The simple substitution cipher is a cipher that has been in use for many hundreds of years
* (an excellent history is given in Simon Singhs 'the Code Book'). * (an excellent history is given in Simon Singhs 'the Code Book').
* It basically consists of substituting every plaintext character for a different ciphertext character. * It basically consists of substituting every plaintext character for a different ciphertext character.
* It differs from the Caesar cipher in that the cipher alphabet is not simply the alphabet shifted, * It differs from the Caesar cipher in that the cipher alphabet is not simply the alphabet shifted,
* it is completely jumbled. * it is completely jumbled.
*
*/ */
public class simpleSubCipher { public class SimpleSubCipher {
/** /**
* Encrypt text by replacing each element with its opposite character. * Encrypt text by replacing each element with its opposite character.
@ -25,7 +24,7 @@ public class simpleSubCipher {
String encoded = ""; String encoded = "";
// This map is used to encode // This map is used to encode
Map<Character,Character> cipherMap = new HashMap<Character,Character>(); Map<Character, Character> cipherMap = new HashMap<>();
char beginSmallLetter = 'a'; char beginSmallLetter = 'a';
char beginCapitalLetter = 'A'; char beginCapitalLetter = 'A';
@ -34,13 +33,13 @@ public class simpleSubCipher {
String cipherCapital = cipherSmall.toUpperCase(); String cipherCapital = cipherSmall.toUpperCase();
// To handle Small and Capital letters // To handle Small and Capital letters
for(int i = 0; i < cipherSmall.length(); i++){ for (int i = 0; i < cipherSmall.length(); i++) {
cipherMap.put(beginSmallLetter++,cipherSmall.charAt(i)); cipherMap.put(beginSmallLetter++, cipherSmall.charAt(i));
cipherMap.put(beginCapitalLetter++,cipherCapital.charAt(i)); cipherMap.put(beginCapitalLetter++, cipherCapital.charAt(i));
} }
for(int i = 0; i < message.length(); i++){ for (int i = 0; i < message.length(); i++) {
if(Character.isAlphabetic(message.charAt(i))) if (Character.isAlphabetic(message.charAt(i)))
encoded += cipherMap.get(message.charAt(i)); encoded += cipherMap.get(message.charAt(i));
else else
encoded += message.charAt(i); encoded += message.charAt(i);
@ -60,7 +59,7 @@ public class simpleSubCipher {
String decoded = ""; String decoded = "";
Map<Character,Character> cipherMap = new HashMap<Character,Character>(); Map<Character, Character> cipherMap = new HashMap<Character, Character>();
char beginSmallLetter = 'a'; char beginSmallLetter = 'a';
char beginCapitalLetter = 'A'; char beginCapitalLetter = 'A';
@ -68,13 +67,13 @@ public class simpleSubCipher {
cipherSmall = cipherSmall.toLowerCase(); cipherSmall = cipherSmall.toLowerCase();
String cipherCapital = cipherSmall.toUpperCase(); String cipherCapital = cipherSmall.toUpperCase();
for(int i = 0; i < cipherSmall.length(); i++){ for (int i = 0; i < cipherSmall.length(); i++) {
cipherMap.put(cipherSmall.charAt(i),beginSmallLetter++); cipherMap.put(cipherSmall.charAt(i), beginSmallLetter++);
cipherMap.put(cipherCapital.charAt(i),beginCapitalLetter++); cipherMap.put(cipherCapital.charAt(i), beginCapitalLetter++);
} }
for(int i = 0; i < encryptedMessage.length(); i++){ for (int i = 0; i < encryptedMessage.length(); i++) {
if(Character.isAlphabetic(encryptedMessage.charAt(i))) if (Character.isAlphabetic(encryptedMessage.charAt(i)))
decoded += cipherMap.get(encryptedMessage.charAt(i)); decoded += cipherMap.get(encryptedMessage.charAt(i));
else else
decoded += encryptedMessage.charAt(i); decoded += encryptedMessage.charAt(i);
@ -84,8 +83,8 @@ public class simpleSubCipher {
} }
public static void main(String[] args) { public static void main(String[] args) {
String a = encode("defend the east wall of the castle","phqgiumeaylnofdxjkrcvstzwb"); String a = encode("defend the east wall of the castle", "phqgiumeaylnofdxjkrcvstzwb");
String b = decode(a,"phqgiumeaylnofdxjkrcvstzwb"); String b = decode(a, "phqgiumeaylnofdxjkrcvstzwb");
System.out.println(b); System.out.println(b);
} }

7
Ciphers/SimpleSubstitutionCipher.java
View File

@ -1,6 +1,7 @@
package Ciphers; package Ciphers;
import java.util.*; import java.util.HashMap;
import java.util.Map;
/** /**
* The simple substitution cipher is a cipher that has been in use for many hundreds of years (an * The simple substitution cipher is a cipher that has been in use for many hundreds of years (an
@ -74,7 +75,9 @@ public class SimpleSubstitutionCipher {
return decoded.toString(); return decoded.toString();
} }
/** TODO remove main and make JUnit Testing */ /**
* TODO remove main and make JUnit Testing
*/
public static void main(String[] args) { public static void main(String[] args) {
String a = encode("defend the east wall of the castle", "phqgiumeaylnofdxjkrcvstzwb"); String a = encode("defend the east wall of the castle", "phqgiumeaylnofdxjkrcvstzwb");
String b = decode(a, "phqgiumeaylnofdxjkrcvstzwb"); String b = decode(a, "phqgiumeaylnofdxjkrcvstzwb");

83
Ciphers/affineCipher.java
View File

@ -1,83 +0,0 @@
package Ciphers;
class affineCipher
{
// Key values of a and b
static int a = 17;
static int b = 20;
static String encryptMessage(char[] msg)
{
/// Cipher Text initially empty
String cipher = "";
for (int i = 0; i < msg.length; i++)
{
// Avoid space to be encrypted
/* applying encryption formula ( a x + b ) mod m
{here x is msg[i] and m is 26} and added 'A' to
bring it in range of ascii alphabet[ 65-90 | A-Z ] */
if (msg[i] != ' ')
{
cipher = cipher
+ (char) ((((a * (msg[i] - 'A')) + b) % 26) + 'A');
} else // else simply append space character
{
cipher += msg[i];
}
}
return cipher;
}
static String decryptCipher(String cipher)
{
String msg = "";
int a_inv = 0;
int flag = 0;
//Find a^-1 (the multiplicative inverse of a
//in the group of integers modulo m.)
for (int i = 0; i < 26; i++)
{
flag = (a * i) % 26;
// Check if (a*i)%26 == 1,
// then i will be the multiplicative inverse of a
if (flag == 1)
{
a_inv = i;
}
}
for (int i = 0; i < cipher.length(); i++)
{
/*Applying decryption formula a^-1 ( x - b ) mod m
{here x is cipher[i] and m is 26} and added 'A'
to bring it in range of ASCII alphabet[ 65-90 | A-Z ] */
if (cipher.charAt(i) != ' ')
{
msg = msg + (char) (((a_inv *
((cipher.charAt(i) + 'A' - b)) % 26)) + 'A');
}
else //else simply append space character
{
msg += cipher.charAt(i);
}
}
return msg;
}
// Driver code
public static void main(String[] args)
{
String msg = "AFFINE CIPHER";
// Calling encryption function
String cipherText = encryptMessage(msg.toCharArray());
System.out.println("Encrypted Message is : " + cipherText);
// Calling Decryption function
System.out.println("Decrypted Message is: " + decryptCipher(cipherText));
}
}