java - GNU Crypto Encrypt returns blank string -

i'm using gnu crypto library encrypt simple strings. believe have followed documentation correctly, problem returns blank string (in case 5 characters) of spaces. i'm not sure whether miss coded or if encoding issue. hope not embarrassingly simple.

import gnu.crypto.cipher.cipherfactory; import gnu.crypto.cipher.iblockcipher; import java.util.hashmap; import java.util.map;  public class ftnsamain {  public static void main(string[] args) throws exception {     string data = "apple";     string key = "abcdefghijklmnop";      byte[] temp = encrypt(data.getbytes(), key.getbytes(), "aes");     system.out.println(new string(temp)); }  public static byte[] encrypt(byte[] input, byte[] key, string algorithm) throws exception {     byte[] output = new byte[input.length];      iblockcipher cipher = cipherfactory.getinstance(algorithm);     map attributes = new hashmap();      attributes.put(iblockcipher.cipher_block_size, 16);     attributes.put(iblockcipher.key_material, key);     cipher.init(attributes);      int bs = cipher.currentblocksize();     (int = 0; + bs < input.length; += bs) {         cipher.encryptblock(input, i, output, i);     }     return output; }  } 

gnu crypto documentation have following void encryptblock(..) methode:

encrypts block of bytes plaintext starting @ inoffset, storing encrypted bytes in ciphertext, starting @ outoffset. programmer ensure there @ least 1 full block in plaintext inoffset , space 1 full block in ciphertext outoffset. java.lang.illegalstateexception thrown if cipher has not been initialized.

your input:

string data = "apple"; 

is not full datablock aes needs data in blocks of 16 bytes. also, output buffer short.

for starters, try encrypting input ends 16 bytes like:

string data = "apple56789abcdef";