algorithm/Java
1
0
Fork 0
mirror of https://github.com/TheAlgorithms/Java.git synced 2025-07-23 04:20:16 +08:00
Code Issues Packages Projects Releases Wiki Activity

Format code with prettier (#3375)

Browse Source
This commit is contained in:
acbin
2022-10-03 17:23:00 +08:00
committed by GitHub
parent 32b9b11ed5
commit e96f567bfc
464 changed files with 11483 additions and 6189 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2586
src/main/java/com/thealgorithms/ciphers/AES.java
View File

File diff suppressed because it is too large Load Diff

19
src/main/java/com/thealgorithms/ciphers/AESEncryption.java
View File

@ -1,8 +1,8 @@
package com.thealgorithms.ciphers;
import javax.crypto.*;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.*;
/**
* This example program shows how AES encryption and decryption can be done in
@ -26,8 +26,12 @@ public class AESEncryption {
String decryptedText = decryptText(cipherText, secKey);
System.out.println("Original Text:" + plainText);
System.out.println("AES Key (Hex Form):" + bytesToHex(secKey.getEncoded()));
System.out.println("Encrypted Text (Hex Form):" + bytesToHex(cipherText));
System.out.println(
"AES Key (Hex Form):" + bytesToHex(secKey.getEncoded())
);
System.out.println(
"Encrypted Text (Hex Form):" + bytesToHex(cipherText)
);
System.out.println("Descrypted Text:" + decryptedText);
}
@ -38,7 +42,8 @@ public class AESEncryption {
* @return secKey (Secret key that we encrypt using it)
* @throws NoSuchAlgorithmException (from KeyGenrator)
*/
public static SecretKey getSecretEncryptionKey() throws NoSuchAlgorithmException {
public static SecretKey getSecretEncryptionKey()
throws NoSuchAlgorithmException {
KeyGenerator aesKeyGenerator = KeyGenerator.getInstance("AES");
aesKeyGenerator.init(128); // The AES key size in number of bits
return aesKeyGenerator.generateKey();
@ -55,8 +60,7 @@ public class AESEncryption {
* @throws IllegalBlockSizeException (from Cipher)
*/
public static byte[] encryptText(String plainText, SecretKey secKey)
throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
IllegalBlockSizeException, BadPaddingException {
throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
// AES defaults to AES/ECB/PKCS5Padding in Java 7
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.ENCRYPT_MODE, secKey);
@ -69,8 +73,7 @@ public class AESEncryption {
* @return plainText
*/
public static String decryptText(byte[] byteCipherText, SecretKey secKey)
throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
IllegalBlockSizeException, BadPaddingException {
throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
// AES defaults to AES/ECB/PKCS5Padding in Java 7
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.DECRYPT_MODE, secKey);

22
src/main/java/com/thealgorithms/ciphers/AffineCipher.java
View File

@ -15,10 +15,9 @@ class AffineCipher {
{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 =
cipher + (char) ((((a * (msg[i] - 'A')) + b) % 26) + 'A');
} else { // else simply append space character
cipher += msg[i];
}
}
@ -46,10 +45,12 @@ class AffineCipher {
{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 =
msg +
(char) (
((a_inv * ((cipher.charAt(i) + 'A' - b)) % 26)) + 'A'
);
} else { //else simply append space character
msg += cipher.charAt(i);
}
}
@ -66,7 +67,8 @@ class AffineCipher {
System.out.println("Encrypted Message is : " + cipherText);
// Calling Decryption function
System.out.println("Decrypted Message is: " + decryptCipher(cipherText));
System.out.println(
"Decrypted Message is: " + decryptCipher(cipherText)
);
}
}

1499
src/main/java/com/thealgorithms/ciphers/Blowfish.java
View File

File diff suppressed because it is too large Load Diff

30
src/main/java/com/thealgorithms/ciphers/Caesar.java
View File

@ -25,21 +25,16 @@ public class Caesar {
final int length = message.length();
for (int i = 0; i < length; i++) {
// int current = message.charAt(i); //using char to shift characters because ascii
// is in-order latin alphabet
char current = message.charAt(i); // Java law : char + int = char
if (IsCapitalLatinLetter(current)) {
current += shift;
encoded.append((char) (current > 'Z' ? current - 26 : current)); // 26 = number of latin letters
} else if (IsSmallLatinLetter(current)) {
current += shift;
encoded.append((char) (current > 'z' ? current - 26 : current)); // 26 = number of latin letters
} else {
encoded.append(current);
}
@ -62,15 +57,11 @@ public class Caesar {
for (int i = 0; i < length; i++) {
char current = encryptedMessage.charAt(i);
if (IsCapitalLatinLetter(current)) {
current -= shift;
decoded.append((char) (current < 'A' ? current + 26 : current)); // 26 = number of latin letters
} else if (IsSmallLatinLetter(current)) {
current -= shift;
decoded.append((char) (current < 'a' ? current + 26 : current)); // 26 = number of latin letters
} else {
decoded.append(current);
}
@ -91,12 +82,13 @@ public class Caesar {
private static boolean IsSmallLatinLetter(char c) {
return c >= 'a' && c <= 'z';
}
/**
* @return string array which contains all the possible decoded combination.
*/
public static String[] bruteforce(String encryptedMessage) {
String[] listOfAllTheAnswers = new String[27];
for (int i=0; i<=26; i++) {
for (int i = 0; i <= 26; i++) {
listOfAllTheAnswers[i] = decode(encryptedMessage, i);
}
@ -117,24 +109,32 @@ public class Caesar {
System.out.println("Please enter the shift number");
shift = input.nextInt() % 26;
System.out.println(
"ENCODED MESSAGE IS \n" + encode(message, shift)); // send our function to handle
"ENCODED MESSAGE IS \n" + encode(message, shift)
); // send our function to handle
break;
case 'D':
case 'd':
System.out.println("Please enter the shift number");
shift = input.nextInt() % 26;
System.out.println("DECODED MESSAGE IS \n" + decode(message, shift));
System.out.println(
"DECODED MESSAGE IS \n" + decode(message, shift)
);
break;
case 'B':
case 'b':
String[] listOfAllTheAnswers = bruteforce(message);
for (int i =0; i<=26; i++) {
System.out.println("FOR SHIFT " + String.valueOf(i) + " decoded message is " + listOfAllTheAnswers[i]);
for (int i = 0; i <= 26; i++) {
System.out.println(
"FOR SHIFT " +
String.valueOf(i) +
" decoded message is " +
listOfAllTheAnswers[i]
);
}
default:
System.out.println("default case");
}
input.close();
}
}

57
src/main/java/com/thealgorithms/ciphers/ColumnarTranspositionCipher.java
View File

@ -12,8 +12,9 @@ public class ColumnarTranspositionCipher {
private static String keyword;
private static Object[][] table;
private static String abecedarium;
public static final String ABECEDARIUM
= "abcdefghijklmnopqrstuvwxyzABCDEFG" + "HIJKLMNOPQRSTUVWXYZ0123456789,.;:-@";
public static final String ABECEDARIUM =
"abcdefghijklmnopqrstuvwxyzABCDEFG" +
"HIJKLMNOPQRSTUVWXYZ0123456789,.;:-@";
private static final String ENCRYPTION_FIELD = "≈";
private static final char ENCRYPTION_FIELD_CHAR = '≈';
@ -49,9 +50,14 @@ public class ColumnarTranspositionCipher {
* @return a String with the word encrypted by the Columnar Transposition
* Cipher Rule
*/
public static String encrpyter(String word, String keyword, String abecedarium) {
public static String encrpyter(
String word,
String keyword,
String abecedarium
) {
ColumnarTranspositionCipher.keyword = keyword;
ColumnarTranspositionCipher.abecedarium = Objects.requireNonNullElse(abecedarium, ABECEDARIUM);
ColumnarTranspositionCipher.abecedarium =
Objects.requireNonNullElse(abecedarium, ABECEDARIUM);
table = tableBuilder(word);
Object[][] sortedTable = sortTable(table);
StringBuilder wordEncrypted = new StringBuilder();
@ -114,7 +120,9 @@ public class ColumnarTranspositionCipher {
* order to respect the Columnar Transposition Cipher Rule.
*/
private static int numberOfRows(String word) {
if (word.length() / keyword.length() > word.length() / keyword.length()) {
if (
word.length() / keyword.length() > word.length() / keyword.length()
) {
return (word.length() / keyword.length()) + 1;
} else {
return word.length() / keyword.length();
@ -139,12 +147,22 @@ public class ColumnarTranspositionCipher {
private static Object[][] sortTable(Object[][] table) {
Object[][] tableSorted = new Object[table.length][table[0].length];
for (int i = 0; i < tableSorted.length; i++) {
System.arraycopy(table[i], 0, tableSorted[i], 0, tableSorted[i].length);
System.arraycopy(
table[i],
0,
tableSorted[i],
0,
tableSorted[i].length
);
}
for (int i = 0; i < tableSorted[0].length; i++) {
for (int j = i + 1; j < tableSorted[0].length; j++) {
if ((int) tableSorted[0][i] > (int) table[0][j]) {
Object[] column = getColumn(tableSorted, tableSorted.length, i);
Object[] column = getColumn(
tableSorted,
tableSorted.length,
i
);
switchColumns(tableSorted, j, i, column);
}
}
@ -164,7 +182,11 @@ public class ColumnarTranspositionCipher {
}
private static void switchColumns(
Object[][] table, int firstColumnIndex, int secondColumnIndex, Object[] columnToSwitch) {
Object[][] table,
int firstColumnIndex,
int secondColumnIndex,
Object[] columnToSwitch
) {
for (int i = 0; i < table.length; i++) {
table[i][secondColumnIndex] = table[i][firstColumnIndex];
table[i][firstColumnIndex] = columnToSwitch[i];
@ -195,13 +217,22 @@ public class ColumnarTranspositionCipher {
public static void main(String[] args) {
String keywordForExample = "asd215";
String wordBeingEncrypted = "This is a test of the Columnar Transposition Cipher";
System.out.println("### Example of Columnar Transposition Cipher ###\n");
String wordBeingEncrypted =
"This is a test of the Columnar Transposition Cipher";
System.out.println(
"### Example of Columnar Transposition Cipher ###\n"
);
System.out.println("Word being encryped ->>> " + wordBeingEncrypted);
System.out.println(
"Word encrypted ->>> "
+ ColumnarTranspositionCipher.encrpyter(wordBeingEncrypted, keywordForExample));
System.out.println("Word decryped ->>> " + ColumnarTranspositionCipher.decrypter());
"Word encrypted ->>> " +
ColumnarTranspositionCipher.encrpyter(
wordBeingEncrypted,
keywordForExample
)
);
System.out.println(
"Word decryped ->>> " + ColumnarTranspositionCipher.decrypter()
);
System.out.println("\n### Encrypted Table ###");
showTable();
}

12
src/main/java/com/thealgorithms/ciphers/HillCipher.java
View File

@ -29,7 +29,7 @@ public class HillCipher {
}
}
//check if det = 0
validateDeterminant(keyMatrix,matrixSize);
validateDeterminant(keyMatrix, matrixSize);
int[][] messageVector = new int[matrixSize][1];
String CipherText = "";
@ -76,7 +76,7 @@ public class HillCipher {
}
}
//check if det = 0
validateDeterminant(keyMatrix,n);
validateDeterminant(keyMatrix, n);
//solving for the required plaintext message
int[][] messageVector = new int[n][1];
@ -155,9 +155,11 @@ public class HillCipher {
}
}
static void validateDeterminant(int[][] keyMatrix, int n){
static void validateDeterminant(int[][] keyMatrix, int n) {
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;
}
}
@ -169,4 +171,4 @@ public class HillCipher {
String message = userInput.nextLine();
hillCipher(message);
}
}
}

16
src/main/java/com/thealgorithms/ciphers/Polybius.java
View File

@ -15,12 +15,12 @@ package com.thealgorithms.ciphers;
public class Polybius {
private static final char[][] key = {
// 0 1 2 3 4
/* 0 */ {'A', 'B', 'C', 'D', 'E'},
/* 1 */ {'F', 'G', 'H', 'I', 'J'},
/* 2 */ {'K', 'L', 'M', 'N', 'O'},
/* 3 */ {'P', 'Q', 'R', 'S', 'T'},
/* 4 */ {'V', 'W', 'X', 'Y', 'Z'}
// 0 1 2 3 4
/* 0 */{ 'A', 'B', 'C', 'D', 'E' },
/* 1 */{ 'F', 'G', 'H', 'I', 'J' },
/* 2 */{ 'K', 'L', 'M', 'N', 'O' },
/* 3 */{ 'P', 'Q', 'R', 'S', 'T' },
/* 4 */{ 'V', 'W', 'X', 'Y', 'Z' },
};
private static String findLocationByCharacter(final char character) {
@ -49,11 +49,11 @@ public class Polybius {
public static String decrypt(final String ciphertext) {
final char[] chars = ciphertext.toCharArray();
final StringBuilder plaintext = new StringBuilder();
for(int i = 0; i < chars.length; i+=2) {
for (int i = 0; i < chars.length; i += 2) {
int pozitionX = Character.getNumericValue(chars[i]);
int pozitionY = Character.getNumericValue(chars[i + 1]);
plaintext.append(key[pozitionX][pozitionY]);
}
return plaintext.toString();
}
}
}

1
src/main/java/com/thealgorithms/ciphers/ProductCipher.java
View File

@ -68,5 +68,4 @@ class ProductCipher {
System.out.println(plaintext);
sc.close();
}
}

28
src/main/java/com/thealgorithms/ciphers/RSA.java
View File

@ -1,8 +1,8 @@
package com.thealgorithms.ciphers;
import javax.swing.*;
import java.math.BigInteger;
import java.security.SecureRandom;
import javax.swing.*;
/**
* @author Nguyen Duy Tiep on 23-Oct-17.
@ -10,14 +10,21 @@ import java.security.SecureRandom;
public final class RSA {
public static void main(String[] args) {
RSA rsa = new RSA(1024);
String text1 = JOptionPane.showInputDialog("Enter a message to encrypt :");
String text1 = JOptionPane.showInputDialog(
"Enter a message to encrypt :"
);
String ciphertext = rsa.encrypt(text1);
JOptionPane.showMessageDialog(null, "Your encrypted message : " + ciphertext);
JOptionPane.showMessageDialog(
null,
"Your encrypted message : " + ciphertext
);
JOptionPane.showMessageDialog(null, "Your message after decrypt : " + rsa.decrypt(ciphertext));
JOptionPane.showMessageDialog(
null,
"Your message after decrypt : " + rsa.decrypt(ciphertext)
);
}
private BigInteger modulus, privateKey, publicKey;
@ -30,7 +37,8 @@ public final class RSA {
* @return encrypted message
*/
public synchronized String encrypt(String message) {
return (new BigInteger(message.getBytes())).modPow(publicKey, modulus).toString();
return (new BigInteger(message.getBytes())).modPow(publicKey, modulus)
.toString();
}
/**
@ -44,7 +52,10 @@ public final class RSA {
* @return plain message
*/
public synchronized String decrypt(String encryptedMessage) {
return new String((new BigInteger(encryptedMessage)).modPow(privateKey, modulus).toByteArray());
return new String(
(new BigInteger(encryptedMessage)).modPow(privateKey, modulus)
.toByteArray()
);
}
/**
@ -63,7 +74,8 @@ public final class RSA {
BigInteger q = new BigInteger(bits / 2, 100, r);
modulus = p.multiply(q);
BigInteger m = (p.subtract(BigInteger.ONE)).multiply(q.subtract(BigInteger.ONE));
BigInteger m =
(p.subtract(BigInteger.ONE)).multiply(q.subtract(BigInteger.ONE));
publicKey = new BigInteger("3");

6
src/main/java/com/thealgorithms/ciphers/SimpleSubCipher.java
View File

@ -84,9 +84,11 @@ public class SimpleSubCipher {
}
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");
System.out.println(b);
}
}

5
src/main/java/com/thealgorithms/ciphers/SimpleSubstitutionCipher.java
View File

@ -85,7 +85,10 @@ public class SimpleSubstitutionCipher {
* TODO remove main and make JUnit Testing
*/
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");
System.out.println(b);
}

32
src/main/java/com/thealgorithms/ciphers/Vigenere.java
View File

@ -9,17 +9,27 @@ package com.thealgorithms.ciphers;
public class Vigenere {
public static String encrypt(final String message, final String key) {
StringBuilder result = new StringBuilder();
for (int i = 0, j = 0; i < message.length(); i++) {
char c = message.charAt(i);
if (Character.isLetter(c)) {
if (Character.isUpperCase(c)) {
result.append((char) ((c + key.toUpperCase().charAt(j) - 2 * 'A') % 26 + 'A'));
result.append(
(char) (
(c + key.toUpperCase().charAt(j) - 2 * 'A') %
26 +
'A'
)
);
} else {
result.append((char) ((c + key.toLowerCase().charAt(j) - 2 * 'a') % 26 + 'a'));
result.append(
(char) (
(c + key.toLowerCase().charAt(j) - 2 * 'a') %
26 +
'a'
)
);
}
} else {
result.append(c);
@ -33,14 +43,20 @@ public class Vigenere {
StringBuilder result = new StringBuilder();
for (int i = 0, j = 0; i < message.length(); i++) {
char c = message.charAt(i);
if (Character.isLetter(c)) {
if (Character.isUpperCase(c)) {
result.append((char) ('Z' - (25 - (c - key.toUpperCase().charAt(j))) % 26));
result.append(
(char) (
'Z' - (25 - (c - key.toUpperCase().charAt(j))) % 26
)
);
} else {
result.append((char) ('z' - (25 - (c - key.toLowerCase().charAt(j))) % 26));
result.append(
(char) (
'z' - (25 - (c - key.toLowerCase().charAt(j))) % 26
)
);
}
} else {
result.append(c);

14
src/main/java/com/thealgorithms/ciphers/a5/A5Cipher.java
View File

@ -4,21 +4,22 @@ import java.util.BitSet;
// https://en.wikipedia.org/wiki/A5/1
public class A5Cipher {
private final A5KeyStreamGenerator keyStreamGenerator;
private static final int KEY_STREAM_LENGTH = 228; // 28.5 bytes so we need to pad bytes or something
public A5Cipher( BitSet sessionKey, BitSet frameCounter ) {
public A5Cipher(BitSet sessionKey, BitSet frameCounter) {
keyStreamGenerator = new A5KeyStreamGenerator();
keyStreamGenerator.initialize( sessionKey, frameCounter );
keyStreamGenerator.initialize(sessionKey, frameCounter);
}
public BitSet encrypt( BitSet plainTextBits ) {
public BitSet encrypt(BitSet plainTextBits) {
// create a copy
var result = new BitSet( KEY_STREAM_LENGTH );
result.xor( plainTextBits );
var result = new BitSet(KEY_STREAM_LENGTH);
result.xor(plainTextBits);
var key = keyStreamGenerator.getNextKeyStream();
result.xor( key );
result.xor(key);
return result;
}
@ -26,5 +27,4 @@ public class A5Cipher {
public void resetCounter() {
keyStreamGenerator.reInitialize();
}
}

36
src/main/java/com/thealgorithms/ciphers/a5/A5KeyStreamGenerator.java
View File

@ -4,6 +4,7 @@ import java.util.BitSet;
// TODO: raise exceptions for improper use
public class A5KeyStreamGenerator extends CompositeLFSR {
private BitSet initialFrameCounter;
private BitSet frameCounter;
private BitSet sessionKey;
@ -11,32 +12,35 @@ public class A5KeyStreamGenerator extends CompositeLFSR {
private static final int KEY_STREAM_LENGTH = 228; // 28.5 bytes so we need to pad bytes or something
@Override
public void initialize( BitSet sessionKey, BitSet frameCounter ) {
public void initialize(BitSet sessionKey, BitSet frameCounter) {
this.sessionKey = sessionKey;
this.frameCounter = (BitSet) frameCounter.clone();
this.initialFrameCounter = (BitSet) frameCounter.clone();
registers.clear();
LFSR lfsr1 = new LFSR( 19, 8, new int[]{ 13, 16, 17, 18 } );
LFSR lfsr2 = new LFSR( 22, 10, new int[]{ 20, 21 } );
LFSR lfsr3 = new LFSR( 23, 10, new int[]{ 7, 20, 21, 22 } );
registers.add( lfsr1 );
registers.add( lfsr2 );
registers.add( lfsr3 );
registers.forEach( lfsr -> lfsr.initialize( sessionKey, frameCounter ) );
LFSR lfsr1 = new LFSR(19, 8, new int[] { 13, 16, 17, 18 });
LFSR lfsr2 = new LFSR(22, 10, new int[] { 20, 21 });
LFSR lfsr3 = new LFSR(23, 10, new int[] { 7, 20, 21, 22 });
registers.add(lfsr1);
registers.add(lfsr2);
registers.add(lfsr3);
registers.forEach(lfsr -> lfsr.initialize(sessionKey, frameCounter));
}
public void reInitialize() {
this.initialize( sessionKey, initialFrameCounter );
this.initialize(sessionKey, initialFrameCounter);
}
public BitSet getNextKeyStream() {
for ( int cycle = 1; cycle <= INITIAL_CLOCKING_CYCLES; ++cycle )
this.clock();
for (
int cycle = 1;
cycle <= INITIAL_CLOCKING_CYCLES;
++cycle
) this.clock();
BitSet result = new BitSet( KEY_STREAM_LENGTH );
for ( int cycle = 1; cycle <= KEY_STREAM_LENGTH; ++cycle ) {
BitSet result = new BitSet(KEY_STREAM_LENGTH);
for (int cycle = 1; cycle <= KEY_STREAM_LENGTH; ++cycle) {
boolean outputBit = this.clock();
result.set( cycle - 1, outputBit );
result.set(cycle - 1, outputBit);
}
reInitializeRegisters();
@ -45,10 +49,10 @@ public class A5KeyStreamGenerator extends CompositeLFSR {
private void reInitializeRegisters() {
incrementFrameCounter();
registers.forEach( lfsr -> lfsr.initialize( sessionKey, frameCounter ) );
registers.forEach(lfsr -> lfsr.initialize(sessionKey, frameCounter));
}
private void incrementFrameCounter() {
Utils.increment( frameCounter, FRAME_COUNTER_LENGTH );
Utils.increment(frameCounter, FRAME_COUNTER_LENGTH);
}
}

19
src/main/java/com/thealgorithms/ciphers/a5/CompositeLFSR.java
View File

@ -6,6 +6,7 @@ import java.util.Map;
import java.util.TreeMap;
public abstract class CompositeLFSR implements BaseLFSR {
protected final List<LFSR> registers = new ArrayList<>();
/**
@ -16,20 +17,24 @@ public abstract class CompositeLFSR implements BaseLFSR {
public boolean clock() {
boolean majorityBit = getMajorityBit();
boolean result = false;
for ( var register : registers ) {
for (var register : registers) {
result ^= register.getLastBit();
if ( register.getClockBit() == majorityBit )
register.clock();
if (register.getClockBit() == majorityBit) register.clock();
}
return result;
}
private boolean getMajorityBit() {
Map<Boolean, Integer> bitCount = new TreeMap<>();
bitCount.put( false, 0 );
bitCount.put( true, 0 );
bitCount.put(false, 0);
bitCount.put(true, 0);
registers.forEach( lfsr -> bitCount.put( lfsr.getClockBit(), bitCount.get( lfsr.getClockBit() ) + 1 ) );
return bitCount.get( false ) <= bitCount.get( true );
registers.forEach(lfsr ->
bitCount.put(
lfsr.getClockBit(),
bitCount.get(lfsr.getClockBit()) + 1
)
);
return bitCount.get(false) <= bitCount.get(true);
}
}

45
src/main/java/com/thealgorithms/ciphers/a5/LFSR.java
View File

@ -3,71 +3,72 @@ package com.thealgorithms.ciphers.a5;
import java.util.BitSet;
public class LFSR implements BaseLFSR {
private final BitSet register;
private final int length;
private final int clockBitIndex;
private final int[] tappingBitsIndices;
public LFSR( int length, int clockBitIndex, int[] tappingBitsIndices ) {
public LFSR(int length, int clockBitIndex, int[] tappingBitsIndices) {
this.length = length;
this.clockBitIndex = clockBitIndex;
this.tappingBitsIndices = tappingBitsIndices;
register = new BitSet( length );
register = new BitSet(length);
}
@Override
public void initialize( BitSet sessionKey, BitSet frameCounter ) {
public void initialize(BitSet sessionKey, BitSet frameCounter) {
register.clear();
clock( sessionKey, SESSION_KEY_LENGTH );
clock( frameCounter, FRAME_COUNTER_LENGTH );
clock(sessionKey, SESSION_KEY_LENGTH);
clock(frameCounter, FRAME_COUNTER_LENGTH);
}
private void clock( BitSet key, int keyLength ) {
private void clock(BitSet key, int keyLength) {
// We start from reverse because LFSR 0 index is the left most bit
// while key 0 index is right most bit, so we reverse it
for ( int i = keyLength - 1; i >= 0; --i ) {
var newBit = key.get( i ) ^ xorTappingBits();
pushBit( newBit );
for (int i = keyLength - 1; i >= 0; --i) {
var newBit = key.get(i) ^ xorTappingBits();
pushBit(newBit);
}
}
@Override
public boolean clock() {
return pushBit( xorTappingBits() );
return pushBit(xorTappingBits());
}
public boolean getClockBit() {
return register.get( clockBitIndex );
return register.get(clockBitIndex);
}
public boolean get( int bitIndex ) {
return register.get( bitIndex );
public boolean get(int bitIndex) {
return register.get(bitIndex);
}
public boolean getLastBit() {
return register.get( length - 1 );
return register.get(length - 1);
}
private boolean xorTappingBits() {
boolean result = false;
for ( int i : tappingBitsIndices ) {
result ^= register.get( i );
for (int i : tappingBitsIndices) {
result ^= register.get(i);
}
return result;
}
private boolean pushBit( boolean bit ) {
private boolean pushBit(boolean bit) {
boolean discardedBit = rightShift();
register.set( 0, bit );
register.set(0, bit);
return discardedBit;
}
private boolean rightShift() {
boolean discardedBit = get( length - 1 );
for ( int i = length - 1; i > 0; --i ) {
register.set( i, get( i - 1 ) );
boolean discardedBit = get(length - 1);
for (int i = length - 1; i > 0; --i) {
register.set(i, get(i - 1));
}
register.set( 0, false );
register.set(0, false);
return discardedBit;
}

11
src/main/java/com/thealgorithms/ciphers/a5/Utils.java
View File

@ -7,15 +7,16 @@ package com.thealgorithms.ciphers.a5;
import java.util.BitSet;
public class Utils {
public static boolean increment( BitSet bits, int size ) {
public static boolean increment(BitSet bits, int size) {
int i = size - 1;
while ( i >= 0 && bits.get( i ) ) {
bits.set( i--, false );/*from w w w . j a v a 2s .c o m*/
while (i >= 0 && bits.get(i)) {
bits.set(i--, false);/*from w w w . j a v a 2s .c o m*/
}
if ( i < 0 ) {
if (i < 0) {
return false;
}
bits.set( i, true );
bits.set(i, true);
return true;
}
}