Why is my java (Tiny Encryption Algorithm) program not working?

Question

package com.teaAlgo;

class TEA {

// Variables

static int sum = 0x0;

static int delta = 0x9e3779b9;

static int lText = 0x12345678;

static int rText = 0x9abcdef;

static int key[] = {0xa56babcd, 0xffffffff, 0xffffffff, 0xabcdef01};

// Main Method

public static void main(String[] args) {

System.out.println("======= Tiny Encryption Algorithm =======");

// Printing Plain Text

System.out.println(String.format("Plain Text is: "+"0x%x", lText) + "" + String.format("%x", rText));

// Calling Encryption

String encText = encrypt(lText, rText);

lText = Integer.parseInt(encText.substring(String.valueOf(lText).length()),16);

rText = Integer.parseInt(encText.substring(String.valueOf(rText).length()),16);

// Calling Decryption

String decText = decrypt(lText, rText);

lText = Integer.parseInt(decText.substring(String.valueOf(lText).length()),16);

rText = Integer.parseInt(decText.substring(String.valueOf(rText).length()),16);

// Printing Key Used

System.out.println("Key Used: 0xa56babcdffffffffffffffffabcdef01 ");

}

//Encryption Method

public static String encrypt (int lText, int rText) {

sum = 0;

//TEA Algorithm for Encrypting

for(int i =0; i <32; i++) {

lText += ( rText << 4 ) + key[0] ^ rText + sum ^ ( rText >>> 5 ) + key[1];

rText += ( lText << 4 ) + key[2] ^ lText + sum ^ ( lText >>> 5 ) + key[3];

sum += delta;

}

// Printing out Encrypted Cipher Text

System.out.println(String.format("Cipher Text is: "+"0x%x", lText) + "" + String.format("%x", rText));

String encText = Integer.toString(lText,16) + Integer.toString(rText,16);

return encText;

}

//Decryption Method

public static String decrypt (int lText, int rText) {

sum = delta << 5;

// TEA Algorithm for Decrypting

for ( int i=0; i<32; i++) {

rText -= ( lText << 4 ) + key[2] ^ lText + sum ^ ( lText >>> 5 ) + key[3];

lText -= ( rText << 4 ) + key[0] ^ rText + sum ^ ( rText >>> 5 ) + key[1];

sum -= delta;

}

// Printing out Decrypted Text

System.out.println(String.format("Decrypted Text is: "+"0x%x", lText) + "" + String.format("%x", rText));

String decText = Integer.toString(lText,16) + Integer.toString(rText,16);

return decText;

}

}

Decryption must match the plain text and I cannot get it to work. it keeps giving me a different output for the decrypted text

Answer 1

Here's the code RELEASED by David Wheeler and Roger Needham...

void encrypt (uint32_t v[2], uint32_t k[4])

{

uint32_t v0=v[0], v1=v[1], sum=0, i;

/* set up */

uint32_t delta=0x9E3779B9; /* a key schedule constant */

uint32_t k0=k[0], k1=k[1], k2=k[2], k3=k[3]; /* cache key */

for (i=0; i<32; i++)

{ /* basic cycle start */

sum += delta;

v0 += ((v1<<4) + k0) ^ (v1 + sum) ^ ((v1>>5) + k1);

v1 += ((v0<<4) + k2) ^ (v0 + sum) ^ ((v0>>5) + k3);

} /* end cycle */

v[0]=v0; v[1]=v1;

}

void decrypt (uint32_t v[2], uint32_t k[4])

{

uint32_t v0=v[0], v1=v[1], sum=0xC6EF3720, i; /* set up; sum is 32*delta */

uint32_t delta=0x9E3779B9; /* a key schedule constant*/

uint32_t k0=k[0], k1=k[1], k2=k[2], k3=k[3]; /* cache key */

for (i=0; i<32; i++)

{ /* basic cycle start */

v1 -= ((v0<<4) + k2) ^ (v0 + sum) ^ ((v0>>5) + k3);

v0 -= ((v1<<4) + k0) ^ (v1 + sum) ^ ((v1>>5) + k1);

sum -= delta;

} /* end cycle */

v[0]=v0; v[1]=v1;

}

It looks like you need an extra pair of parenthesis, end parens being before each exponent..

I also notice you are referencing key[2] (the 3rd element) while the published code references key[1], the second element.

I would copy and paste the code. It is public domain. Make sure you are using unsigned 32 bit integers