java - Speck algorithm not working -

i trying implement speck 64bit block / 128bit key cipher in java. i'm stuck @ encryption / decryption algorithm. decryption algorithm can't decrypt cipher text properly.

my implementation:

• encryption:

  int m = 4; //key words int t = 27; //rounds int alpha = 8; //alpha int beta = 3; //beta int x,y; int[] l = new int[2*t], k = new int[t]; /* *************** key extenstion ***************** */ for(int = 0; < t-1; i++) {     l[i+m-1] = (k[i] + rotateright(l[i], alpha)) ^ i;     k[i+1] = rotateleft(k[i], beta) ^ l[i+m-1];      //system.out.println(k[i]); } /* *************** encryption ********************* */ for(int = 0; < t; i++) {     x = (rotateleft(x, alpha) + y) ^ k[i];     y = rotateright(y, beta) ^ x;     //system.out.println(y); } 

• decryption:

  /* *************** key extenstion ***************** */ for(int = 0; < t-1; i++) {     l[i+m-1] = (k[i] + rotateright(l[i], alpha)) ^ i;     k[i+1] = rotateleft(k[i], beta) ^ l[i+m-1];     //system.out.println(k[i]); } /* *************** decryption ********************* */          for(int = t-1; >= 0; i--) {     y = rotateright(y, beta) ^ x;     x = (rotateleft(x, alpha) - y) ^ k[i];     //system.out.println(y); } 

x , y initialized function boxing(<- little bit weird):

    x = boxing(plaintext, 0, 1);     y = boxing(plaintext, 1, 2);  public static int boxing(int[] content, int i, int count) {     int temp[] = new int[count];         temp[i] |= content[i*4] & 0xff;         temp[i] = temp[i] << 8 | content[i*4+1] & 0xff;         temp[i] = temp[i] << 8 | content[i*4+2] & 0xff;         temp[i] = temp[i] << 8 | content[i*4+3] & 0xff;         //system.out.println(temp[from]);      return temp[i]; } 

note content int array of 8 characters.

i put decryption right behind encryption, see if algorithm working, isn't , don't know why. (i reset variables proper values, before used decryption).

references

• the simon , speck families of lightweight block ciphers https://eprint.iacr.org/2013/404
• speck implementation (not mine)
  https://github.com/timw/bc-java/blob/feature/simon-speck/core/src/main/java/org/bouncycastle/crypto/engines/speckengine.java

edit:

• rotate functions:

  public static int rotateleft(int number, int amount) {    return number << amount | number >>> (32-amount); } public static int rotateright(int number, int amount) {    return number >>> amount | number << (32-amount); } 

finally figured out. decryption algorithm should this:

    for(int = t-1; >= 0; i--) {         y = rotateright(x ^ y, beta);         x = rotateleft((x ^ k[i]) - y, alpha);     } 

and accidently swap rotate functions in encryption algorithm. correct form:

    for(int = 0; < t; i++) {         x = (rotateright(x, alpha) + y) ^ k[i];         y = rotateleft(y, beta) ^ x;     }