Railfence Columnar Cipher

This is the combination of Rail fence Cipher with Columnar implementation..

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import java.util.*; public class RFwithColumnar { public static void main(String[] args) { String text = "IF YOU CAN READ THIS YOU ARE GENIUS"; String key = "HACK"; String enc = RFCEncryption(text, key); System.out.println(enc); } public static String RFCEncryption(String text, String keytext) { int[] arrange = arrangeKey(keytext); int key = arrange.length; int lentext = text.length(); int move = 1; int count = 0; String[][] rfp = new String[key][lentext]; // arrange dot fence for (int x = 0; x < rfp.length; x++) { for (int y = 0; y < rfp[x].length; y++) { rfp[x][y] = "."; } } // formatting according fence rails for (int i = 0; i < lentext; i++) { if ((move % 2) != 0) { rfp[count][i] = "" + text.charAt(i); if (count == (key - 1)) { move = 2; count = (key - 2); } else count++; } else if ((move % 2) == 0) { rfp[count][i] = "" + text.charAt(i); if (count == 0) { move = 1; count = 1; } else count--; } } //replace any white space with X or random for (int x = 0; x < rfp.length; x++) { for (int y = 0; y < rfp[x].length; y++) { if (rfp[x][y].equals(" ")) rfp[x][y] = ""+Character.toUpperCase(RandomAlpha()); } } // display System.out.println(); for (int i = 0; i < rfp.length; i++) { for (int u = 0; u < rfp[i].length; u++) { System.out.print(rfp[i][u] + " "); } System.out.println(); } System.out.println(); StringBuilder cb = new StringBuilder(); //encode string from fence for (int x = 0; x < key; x++) { for (int y = 0; y < key; y++) { if (x == arrange[y]) { for (int u = 0; u < lentext; u++) { if (!".".equals(rfp[y][u])) { cb.append(rfp[y][u]); } } } } } return "" + cb; } public static int[] arrangeKey(String key) { //arrange position of grid String[] keys = key.split(""); Arrays.sort(keys); int[] num = new int[key.length()]; for (int x = 0; x < keys.length; x++) { for (int y = 0; y < key.length(); y++) { if (keys[x].equals(key.charAt(y) + "")) { num[y] = x; break; } } } System.out.println(Arrays.toString(num)); return num; } public static char RandomAlpha() { //generate random alpha for null space Random r = new Random(); return (char)(r.nextInt(26) + 'a'); } }

Scratch Programming

Scratch programming is very interesting after joining Volunteer Digital Tech @ Schools at Knowledge Development Center (KDC) under MDeC and ARUS. Scratch is an IDE where just using your creativity to drag and drop any block or function to match any of your animation you want. Just like Greenfoot programming but scratch is focus more on kids where there is no code involved and easy to the kids how to create animation they want. 

What is scratch programming?

Scratch is a programming language and an online community where children can program and share interactive media such as stories, games, and animation with people from all over the world. As children create with Scratch, they learn to think creatively, work collaboratively, and reason systematically.

Below is the example of block in scratch programming

Below is the examples of what i manage to do with scratch programming. I am using a lot of blocks just to create a pong games..

This is the examples where people share their animation --> https://scratch.mit.edu

During our training..this is what we do so far --> https://scratch.mit.edu/studios/1599700/

Have the best luck!..

Random alphabet character with no duplicate

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public static String RandomAlpha(int len){ Random r = new Random(); String key = ""; for(int x=0;x<len;x++) key = key + (char) (r.nextInt(26) + 'A'); return key; } public static String RandomAlphaNoDuplicate(int len){ Random r = new Random(); String key = ""; for (int i = 0; i < len;) { char c = (char) (r.nextInt(26) + 'A'); if(!key.toString().contains(""+c)){ key = key + c; i++; } } return key; }

Kamasutra Cipher

One of the earliest descriptions of encryption by substitution appears in the Kama-sutra, a text written in the 4th century AD by the Brahmin scholar Vatsyayana, but based on manuscripts dating back to the 4th century BC. The Kama-sutra recommends that women should study 64 arts, including cooking, dressing, massage and the preparation of perfumes. The list also includes some less obvious arts, including conjuring, chess, bookbinding and carpentry. Number 45 on the list is mlecchita-vikalpa, the art of secret writing, advocated in order to help women conceal the details of their liaisons. One of the recommended techniques involves randomly pairing letters of the alphabet, and then substituting each letter in the original message with its partner.4

How it work
The kamasutra generate list of 26 alphabet with no duplicate. Then divide by 2 row. Find for each letter of message text in table and choose the opposite of the letter

for example:

Key = G H A J R I O B E S Q C L F V Z T Y K M X W N U D P

divide by 2 rows

G H A J R I O B E S Q C L
F V Z T Y K M X W N U D P

Given String = KAMASUTRA

K is at 2nd row and 5th column. Get the opposite of K that is I. Do each letter until the end

Cipher : IZOZNQJYZ

To decyrpt the cipher, use the table with same random list of 26 alphabet. Without the key is difficult to decrypt because of  26! = 403,291,461,000,000,000,000,000,000 = 403 septilion of combination of key can be produce uniquely.

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/* authors by hafiq Kamasutra Cipher and decrytion any expert can advise me to improve this code...tq.. */ import java.util.*; public class KSCipher{ public static void main(String[] args){ String text = "KAMA SUTRA CIPHER"; String key = RandomAlphaNoDuplicate(26); String enc = KSutra(text,key); System.out.println("Encryption: "+ enc); String dec = KSutra(enc,key); System.out.println("Decryption: "+ dec); } public static String RandomAlphaNoDuplicate(int len){ Random r = new Random(); String key = ""; for (int i = 0; i < len;) { char c = (char) (r.nextInt(26) + 'A'); if(!key.toString().contains(""+c)){ key = key + c; i++; } } return key; } public static String KSutra(String text,String key){ int keyLen = key.length()/2; // arrange random key char[][] keyRow = new char[2][keyLen]; int count=0; for(int x=0;x<2;x++){ for(int y=0;y<keyLen;y++){ keyRow[x][y] = key.charAt(count); System.out.print(keyRow[x][y]+" "); count++; } System.out.println(); } String sb = ""; count=0; for(int x=0;x<text.length();x++){ for(int y=0;y<2;y++){ for(int z=0;z<keyLen;z++){ if(y == 0){ if(text.charAt(x) == keyRow[y][z]) sb += keyRow[y+1][z]; } else if (y == 1){ if(text.charAt(x) == keyRow[y][z]) sb += keyRow[y-1][z]; } } } if(text.charAt(x) == ' ') sb += text.charAt(x); } return sb; } }

One-Time Pad Cipher

In cryptography, the one-time pad (OTP) is an encryption technique that cannot be cracked if used correctly. It was invented near the end of WWI by Gilbert Vernam and Joseph Mauborgne in the US. It was mathematically proven unbreakable by Claude Shannon, probably during WWII, his work was first published in the late 1940s.

How it work

In this technique, a plaintext is paired with a random secret key (also referred to as a one-time pad). Then, each bit or character of the plaintext is encrypted by combining it with the corresponding bit or character from the pad using modular addition. If the key is truly random, is at least as long as the plaintext, is never reused in whole or in part, and is kept completely secret, then the resulting ciphertext will be impossible to decrypt or break.

Are one-time pads really unbreakable?

Yes. But only if used properly. A one-time pad must be truly random data and must be kept secure in order to be unbreakable. Consider if the one-time pad is used to encode the word "otter." If an attacker tries to brute force "guess" the contents of the pad, the message will "decrypt" into every possible combination of 6 characters (e.g.: "lemur." "badger" etc..) Since the pad is truly random there are no statistical methods that the attacker can hope to use to infer which combination is correct.

Below is the example of one time cipher work

In this example, the technique is to combine the key and the message using modular addition. The numerical values of corresponding message and key letters are added together, modulo 26 (%26). So, if key randomly begins with "XMCKL" and the message is "HELLO", then the coding would be done as follows:

Calculation:

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
0 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

H + X = E because 7 + 23 = 30 % 26 = 4 is E

E + M = Q because 4 + 12 = 16 % 26 = 16 is Q

so on..

      H       E       L       L       O  message
   7 (H)   4 (E)  11 (L)  11 (L)  14 (O) message
+ 23 (X)  12 (M)   2 (C)  10 (K)  11 (L) key
= 30      16      13      21      25     message + key
=  4 (E)  16 (Q)  13 (N)  21 (V)  25 (Z) message + key (mod 26)
      E       Q       N       V       Z  → ciphertext

Ciphertext = EQNVZ
This is similar with caesar cipher. This simply means that if the computations "go past" Z, the sequence starts again at A.

Now, Let's Decrypt

The ciphertext is "EQNVZ". Use the matching key and the same process but in reverse to obtain the plaintext. Here the key is subtracted from the ciphertext again using modular arithmetic:

       E       Q       N       V       Z  ciphertext
    4 (E)  16 (Q)  13 (N)  21 (V)  25 (Z) ciphertext
-  23 (X)  12 (M)   2 (C)  10 (K)  11 (L) key
= -19       4      11      11      14     ciphertext – key
=   7 (H)   4 (E)  11 (L)  11 (L)  14 (O) ciphertext – key (mod 26)
       H       E       L       L       O  → message

Text = HELLO

However, it is difficult to ensure that the key is actually random is used only once, never becomes known to the opposition and is completely destroyed after use. The auxiliary parts of a software one-time pad implementation present real challenges: secure handling/transmission of plaintext truly random keys and one-time-only use of the key.

Generate list of Permutation of N length

In cryptography, a brute-force attack, or exhaustive key search, is a cryptanalytic attack that can, in theory, be used against any encrypted data.

Brute force attacks work by calculating every possible combination that could make up a password and testing it to see if it is the correct password. As the password’s length increases, the amount of time, on average, to find the correct password increases exponentially. This means short passwords can usually be discovered quite quickly, but longer passwords may take decades.

String list is A-z. Length is 26 + 26 = 52 character.

the combination of 5 character is

52 * 52 * 52 * 52 *52 = 52^5 = 380204032 combination !!!


Below is the example of brute force.

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import java.util.*; /* modified by hafiq Brute force list ex: a..aaab..aaaaaaC.... any expert can advise me to improve this code...tq.. */ public class Bruteforce { public static void main(String[] args){ String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; int max = 4; //limit length generate(str.toCharArray(),max); } public static void generate(char[] input,int max) { char[] result = new char[input.length]; int[] index = new int[input.length]; // initialize the arrays. Arrays.fill(result, 0, result.length, input[0]); Arrays.fill(index, 0, index.length, 0); // loop over the output lengths. for( int length = 1; length <= max; length++ ) { int update = 0; while(update != -1){ System.out.println(new String(result, 0, length)); // update values that need to reset. for(update = length-1; update != -1 && ++index[update] == input.length; result[update] = input[0], index[update] = 0, update--); // update the character that is not resetting, if valid if( update != -1 ) result[update] = input[index[update]]; } } } }

Vigenere cipher

The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution.

This cipher is similar with caesar cipher but different in term of shifting. The Vigenère cipher consists of several Caesar ciphers in sequence with different shift values. To encrypt, a table of alphabets can be used called Vigenère table. It consists of the alphabet written out 26 times in different rows, each alphabet shifted cyclically to the left compared to the previous alphabet, corresponding to the 26 possible Caesar ciphers.

Vigenere table

For example, suppose that the plaintext to be encrypted is:

Let Encrypt the text

Given string : ATTACKATDAWN

For the key, for example "LEMON". Repeat the word "LEMON" until the length of key is the same of the text length.

Key : LEMONLEMONLE

Then, compare the text and key using vigenere table.

Plaintext: ATTACKATDAWN
Key:         LEMONLEMONLE

Key is the row and plaintext is the column. for example, ROW L and COLUMN A is L. ROW E and COLUMN T is X and so on.

Cipher:    LXFOPVEFRNHR

Note: just ignore the null or replace with other alphabet


Let Decrypt the cipher

Cipher:    LXFOPVEFRNHR
Key:        LEMONLEMONLE

Key is the column. at L column find the letter Cipher L and the row letter is A. at E column find the letter Cipher X and the row letter is T and so on until you get

Plaintext: ATTACKATDAWN

To decrypt Vigenere cipeher without Key is difficult..This cipher was so strong because by swapping between all 26 possible Caesar ciphers it reduced the effectiveness of frequency analysis.

But during the Crimean War of the 1850s, Charles Babbage, under pressure of the British government, broke this cipher. The steps are :-

1. Look for sequences of letters that appear more than once in the ciphertext.
2. Then used vigenere table to find the most common spacing factor to identify the length of the keyword.
3. Having established the length of the keyword and performed a frequency analysis of the portion of the ciphertext corresponding to that letter.
4. Then, matched the frequency analysis data to the frequency in normal english to find that letter of the keyword.
5. Repeated this for every letter in the keyword.

The Rail Fence Cipher and how to decrypt

The Rail Fence Cipher is a type of transposition cipher. A transposition cipher involves the rearranging of the letters in the plaintext to encrypt the message. This is in contrast to a substitution cipher, in which the plaintext letters are replaced by letters from another alphabet (or by different letters from the same alphabet).

note: The rail fence cipher is not very strong; the number of practical keys (the number of rails) is small enough that a crypt analyst can try them all by hand.

In the rail fence cipher, the plaintext is written downwards and diagonally on successive "rails" of an imaginary fence, then moving up when we reach the bottom rail. When we reach the top rail, the message is written downwards again until the whole plaintext is written out. The message is then read off in rows. For example, if we have 4 "rails" and a message of 'REPEAT ATTACK TONIGHT', the cipherer writes out:

3 rails

R . . . A . . . T . . . K . . . N . . . T
. E . E . T . A . T . C . X . O . I . H .
. . P . . . X . . . A . . . T . . . G . .

Encrypted :RATKNTEETATCXOIHPXATG

4 rails

R . . . . . X . . . . . K . . . . . G . .
. E . . . T . A . . . C . X . . . I . H .
. . P . A . . . T . A . . . T . N . . . T
. . . E . . . . . T . . . . . O . . . . .

Encrypted :RXKGETACXIHPATATNTETO

Note: Space in text are replaced with any suitable random alphabet. in this case iam using 'X' as replace of white space

Download code :- RFcipher

oopss.. i miss how to decrypt without key

2. Decrypt without key

In railfence cipher, the maximun level we can make is the length of text. If the ciphertext length is 100, so the maximum level is 100. To decrypt that ciphertext, the possibility of correct message will get is 100.  Below is example of decrypt without key..

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/* authors by hafiq Rail Fence cipher and decrypt with key and no key any expert can advise me to improve this code...tq.. */ import java.util.*; public class RFCipher { public static void main(String[] args) { Scanner scan = new Scanner(System.in); String line = System.getProperty("line.separator"); scan.useDelimiter(line); System.out.print("1. Encrypt 2. Decrypt :"); int option = scan.nextInt(); switch (option) { case 1: System.out.print("Enter Plain Text: "); String text = scan.next(); System.out.print("Enter Key Level [more than 1] :"); int key = scan.nextInt(); if (key > 1) { String enc = RFEncryptionWork(key, text); System.out.println("Encrypted :" + enc); } else System.out.println("invalid level"); break; case 2: System.out.print("Enter Cipher text: "); String enc = scan.next(); System.out.print("1. No key 2. With Key: "); int k = scan.nextInt(); if(k==1){ String[] dec = RFDecryptionWork(enc); for (String a: dec) { System.out.println(a); } } else{ System.out.print("Enter Key Level [more than 1] :"); key = scan.nextInt(); String dec = RFDecryptionWork(enc,key); System.out.println("Decrypted :"+dec); } break; default: break; } } static String RFEncryptionWork(int key, String text) { int move = 1; int count = 0; String[][] rfp = new String[key][text.length()]; // arrange dot fence for (int x = 0; x < rfp.length; x++) { for (int y = 0; y < rfp[x].length; y++) { rfp[x][y] = "."; } } // formatting according fence rails for (int i = 0; i < text.length(); i++) { if ((move % 2) != 0) { rfp[count][i] = "" + text.charAt(i); if (count == (key - 1)) { move = 2; count = (key - 2); } else count++; } else if ((move % 2) == 0) { rfp[count][i] = "" + text.charAt(i); if (count == 0) { move = 1; count = 1; } else count--; } } //replace any white space with X or random for (int x = 0; x < rfp.length; x++) { for (int y = 0; y < rfp[x].length; y++) { if (rfp[x][y].equals(" ")) rfp[x][y] = "X"; } } // display System.out.println(); for (int i = 0; i < rfp.length; i++) { for (int u = 0; u < rfp[i].length; u++) { System.out.print(rfp[i][u] + " "); } System.out.println(); } System.out.println(); StringBuilder cb = new StringBuilder(); //encode string from fence for (int i = 0; i < rfp.length; i++) { for (int u = 0; u < rfp[i].length; u++) { if (!".".equals(rfp[i][u])) { cb.append(rfp[i][u]); } } } return "" + cb; } static String[] RFDecryptionWork(String text) { String[] ans = new String[text.length() - 2]; for (int z = 2; z < text.length(); z++) { int key = z; String[][] rfp = new String[key][text.length()]; for (int x = 0; x < rfp.length; x++) { for (int y = 0; y < rfp[x].length; y++) { rfp[x][y] = "."; } } // arrange accroding to fence rail int count = 0; int c = 1; int a = 0, b = 0; int init = (2 * key) - 2; a = init - 2; b = 2; for (int i = 0; i < rfp.length; i++) { c = 0; for (int u = i; u < rfp[i].length;) { if (count != text.length()) { if (i == 0 || i == key - 1) { rfp[i][u] = "" + text.charAt(count); u = u + init; } else { rfp[i][u] = "" + text.charAt(count); if (c % 2 == 0) u = u + a; else if (c % 2 == 1) u = u + b; c++; } count++; } else break; } if (i != 0 && i != key - 1) { a = a - 2; b = b + 2; } } int move = 1; count = 0; String sb = ""; for (int i = 0; i < text.length(); i++) { if ((move % 2) != 0) { sb = sb + rfp[count][i]; if (count == (key - 1)) { move = 2; count = (key - 2); } else count++; } else if ((move % 2) == 0) { sb = sb + rfp[count][i]; if (count == 0) { move = 1; count = 1; } else count--; } } ans[z - 2] = sb; } return ans; } static String RFDecryptionWork(String text, int key) { String[][] rfp = new String[key][text.length()]; for (int x = 0; x < rfp.length; x++) { for (int y = 0; y < rfp[x].length; y++) { rfp[x][y] = "."; } } // arrange accroding to fence rail int count = 0; int c = 1; int a = 0, b = 0; int init = (2 * key) - 2; a = init - 2; b = 2; for (int i = 0; i < rfp.length; i++) { c = 0; for (int u = i; u < rfp[i].length;) { if (count != text.length()) { if (i == 0 || i == key - 1) { rfp[i][u] = "" + text.charAt(count); u = u + init; } else { rfp[i][u] = "" + text.charAt(count); if (c % 2 == 0) u = u + a; else if (c % 2 == 1) u = u + b; c++; } count++; } else break; } if (i != 0 && i != key - 1) { a = a - 2; b = b + 2; } } //display System.out.println("\n\nDecrypting..list into table"); for (int i = 0; i < rfp.length; i++) { for (int u = 0; u < rfp[i].length; u++) { System.out.print(rfp[i][u] + " "); } System.out.println(); } int move = 1; count = 0; String sb = ""; for (int i = 0; i < text.length(); i++) { if ((move % 2) != 0) { sb = sb + rfp[count][i]; if (count == (key - 1)) { move = 2; count = (key - 2); } else count++; } else if ((move % 2) == 0) { sb = sb + rfp[count][i]; if (count == 0) { move = 1; count = 1; } else count--; } } return sb; } }