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Encryption program overhaul and a minor change in the TextServer program
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@ThePurpleJedi
ThePurpleJedi committed Feb 12, 2022
1 parent 0cd1abb commit 9ee713a
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4 changes: 0 additions & 4 deletions .idea/sonarlint/issuestore/index.pb
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5 changes: 3 additions & 2 deletions src/com/mercurys/TextServer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,9 +14,10 @@ public class TextServer {

private TextServer(final int port) {
try (final ServerSocket serverSocket = new ServerSocket()) {
serverSocket.bind(new InetSocketAddress("192.168.0.151", port));
String hostAddress = "192.168.0.151"; //replace with one's own LAN IP address
serverSocket.bind(new InetSocketAddress(hostAddress, port));
System.out.println("""
Server initiated.
Server initialised.
Waiting for client...""");

this.socket = serverSocket.accept();
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151 changes: 67 additions & 84 deletions src/com/mercurys/encryption/Encryption.java
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Original file line number Diff line number Diff line change
Expand Up @@ -5,60 +5,45 @@
public class Encryption {

private final String specialChars;
private final char[] key;
private String chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
private String[] words;

public Encryption(final String specialChars) {
this.specialChars = specialChars;
this.chars = this.chars + specialChars;
this.key = new char[this.chars.length()];
}

public Encryption() {
this.specialChars = "!(),–.:;?’'-*/+=<>{}[]#@^&";
this.chars = this.chars + this.specialChars;
this.key = new char[this.chars.length()];
}

public String encrypt(final String msg) {

//get input
this.words = msg.split(" +");
String[] words = msg.split(" +");
char[] key = new char[this.chars.length()];

//shift letters by 7 places
//we do not rotate the special chars or digits
this.rotateFullMessageBy7();
this.rotateFullMessageBy7(words);
words = this.reverse(words);
words = this.perfectSquareSwap(words);
this.generateRandomKey(key);
this.translateUsingKey(words, key);

//reverse letter sequence in individual words, and reverse word sequence in sentences
this.reverse();

//swap words at perfect square position
this.perfectSquareSwap();

//generate a random "key" for the message
this.generateRandomKey();

//translate the message using the encryption key
this.translateUsingKey();

//display final encrypted message, with attached encryption key in 8 letter fragments mixed into the message
return this.getFinalEncryptedMessage();
return this.getFinalEncryptedMessage(words, key);
}

private void rotateFullMessageBy7() {
for (int i = 0; i < this.words.length; i++) {
private void rotateFullMessageBy7(String[] words) {
for (int i = 0; i < words.length; i++) {
final StringBuilder encodedWord = new StringBuilder();

for (int j = 0; j < this.words[i].length(); j++) {
final char c = this.words[i].charAt(j);
for (int j = 0; j < words[i].length(); j++) {
final char c = words[i].charAt(j);
if (this.chars.indexOf(c) != -1) {
encodedWord.append(this.rotateLetterBy7(c));
} else if (c == '|') {
encodedWord.append(c);
}
}
this.words[i] = encodedWord.toString();
words[i] = encodedWord.toString();
}
}

Expand All @@ -84,95 +69,93 @@ private char rotateLetterBy7(char c) {
return c;
}

private void reverse() {
private String[] reverse(String[] words) {
final StringBuilder msg = new StringBuilder();

for (int i = this.words.length - 1; i >= 0; i--) {
this.words[i] = new StringBuilder(this.words[i]).reverse().toString();
msg.append(this.words[i]).append(" ");
for (int i = words.length - 1; i >= 0; i--) {
words[i] = new StringBuilder(words[i]).reverse().toString();
msg.append(words[i]).append(" ");
}
this.words = msg.toString().split(" +");
return msg.toString().split(" +");
}

private void perfectSquareSwap() {
private String[] perfectSquareSwap(String[] words) {
int n = 1;
final List<String> ls = new ArrayList<>(Arrays.asList(this.words));
for (int i = 1; i < this.words.length; i += 2 * (n++) + 1) {
final List<String> ls = new ArrayList<>(Arrays.asList(words));
for (int i = 1; i < words.length; i += 2 * (n++) + 1) {
Collections.swap(ls, i, i - 1);
}
this.words = ls.toArray(this.words);
return ls.toArray(words);
}

private void generateRandomKey() {
for (int i = 0; i < this.key.length; i++) {
private void generateRandomKey(char[] key) {
for (int i = 0; i < key.length; i++) {
char c = (char) (92 * Math.random() + 33);
while (String.valueOf(this.key).indexOf(c) != -1 || c == '|') {
while (String.valueOf(key).indexOf(c) != -1 || c == '|') {
c = (char) (92 * Math.random() + 33);
}
this.key[i] = c;
key[i] = c;
}
System.out.println("key length = " + key.length);
}

private void translateUsingKey() {
for (int i = 0; i < this.words.length; i++) {
final char[] letters = this.words[i].toCharArray();
private void translateUsingKey(String[] words, char[] key) {
for (int i = 0; i < words.length; i++) {
final char[] letters = words[i].toCharArray();

for (int j = 0; j < letters.length; j++) {
letters[j] = (letters[j] != '|')? this.key[this.chars.indexOf(letters[j])] : '|';
letters[j] = (letters[j] != '|')? key[this.chars.indexOf(letters[j])] : '|';
}

this.words[i] = String.valueOf(letters);
words[i] = String.valueOf(letters);
}
}

private String getFinalEncryptedMessage() {
private String getFinalEncryptedMessage(String[] words, char[] key) {
final StringBuilder encryptedMessage = new StringBuilder();
final int fragmentLength = 8;
final int fragmentNumber = this.key.length / 8;
int n = 1;
double k = Math.ceil((double) this.words.length / fragmentNumber);
int fragmentNumber = 0; //goes from 1 to fragmentNumber - 2

encryptedMessage.append(this.specialChars);
encryptedMessage.append(" ~"); //print first key fragment
for (int i = 0; i < fragmentLength; i++) {
encryptedMessage.append(this.key[i]);
encryptedMessage.append(" ");
this.appendKeyFragment(key, fragmentNumber++, encryptedMessage);

for (int i = 0; i < words.length; i++) {
encryptedMessage.append(words[i]).append(" ");
fragmentNumber = addKeyFragmentsInMessage(encryptedMessage, key, i, words.length, fragmentNumber);
}
encryptedMessage.append("~ ");
appendKeyFragment(key, fragmentNumber, encryptedMessage);
return encryptedMessage.toString();
}

for (int i = 0; i < this.words.length; i++) {
encryptedMessage.append(this.words[i]).append(" ");
private int addKeyFragmentsInMessage(StringBuilder encryptedMessage, char[] key, int i,
int numberOfWords, int fragmentNumber) {

if (this.words.length > fragmentNumber) {
if (((int) k) == i && n < fragmentNumber - 1) {
encryptedMessage.append(this.getKeyFragment(n, n + 1));
k += Math.round((double) this.words.length / fragmentNumber);
n++;
}
} else if (this.words.length > 1) {
if (i == this.words.length / 2 - 1) {
encryptedMessage.append(this.getKeyFragment(1, 10));
final int numberOfFragments = key.length / 8;
if (numberOfWords > numberOfFragments) {
double nextFragmentPosition = Math.ceil(fragmentNumber * (double) numberOfWords / numberOfFragments);
if (((int) nextFragmentPosition) == i && fragmentNumber < numberOfFragments - 1) {
this.appendKeyFragment(key, fragmentNumber, encryptedMessage);
fragmentNumber++;
}
} else if (numberOfWords > 1) {
if (i == numberOfWords / 2 - 1) {
for (; fragmentNumber < 10; fragmentNumber++) {
this.appendKeyFragment(key, fragmentNumber, encryptedMessage);
}
} else {
encryptedMessage.append(this.getKeyFragment(1, 10));
}
} //mix the key in the message

encryptedMessage.append("~"); //print last key fragment
for (int i = 10 * fragmentLength; i < this.key.length; i++) {
encryptedMessage.append(this.key[i]);
} else {
for (; fragmentNumber < 10; fragmentNumber++) {
this.appendKeyFragment(key, fragmentNumber, encryptedMessage);
}
}
encryptedMessage.append("~");

return encryptedMessage.toString();
return fragmentNumber;
}

private String getKeyFragment(final int startIndex, final int endIndex) {
final StringBuilder fragment = new StringBuilder();
fragment.append("~");
for (int j = startIndex * 8; j < endIndex * 8; j++) {
fragment.append(this.key[j]);
private void appendKeyFragment(char[] key, final int fragmentNumber, StringBuilder encryptedMessage) {
encryptedMessage.append("~");
for (int j = fragmentNumber * 8; j < (fragmentNumber + 1) * 8; j++) {
encryptedMessage.append(key[j]);
}
fragment.append("~ ");

return fragment.toString();
encryptedMessage.append("~ ");
}
}

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