java - Can't fix "Error: Input length must be a multiple of 16 when decrypting with a pad cipher" -

ello! working chat application encrypts it's data through aes/cbc/pkcs5 padding. works through client sending encrypted message server sent , decrypted. unfortunately, whenever decrypt message, error follows: javax.crypto.illegalblocksizeexception: input length must multiple of 16 when decrypting padded cipher. encryption based of program :(http://www.scottjjohnson.com/blog/aeswithcbcexample.java) works fine , cannot see difference between code , 1 except must convert string byte array. here code code:

client (encryption):

string message = textfield.gettext(); // generate key keygenerator keygen = keygenerator.getinstance("aes"); keygen.init(128);  // use 256 bit keys, need "unlimited strength" encryption policy files sun. byte[] key = keygen.generatekey().getencoded(); secretkeyspec skeyspec = new secretkeyspec(key, "aes");  // build initialization vector.  example zeros,  // value or generated using random number generator. byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; ivparameterspec ivspec = new ivparameterspec(iv);  // initialize cipher encrypt mode cipher cipher = cipher.getinstance("aes/cbc/pkcs5padding"); cipher.init(cipher.encrypt_mode, skeyspec, ivspec);  // encrypt message byte[] encrypted = cipher.dofinal(message.getbytes()); system.out.println("ciphertext: " + encrypted + "\n"); system.out.println(encrypted); out.println(encrypted); textfield.settext("");  

server side:

string input = in.readline(); writer.println("message " + input); 

client (decryption):

//decryption system.out.println(line); line = line.substring(8); system.out.println(line);  // generate key keygenerator keygen = keygenerator.getinstance("aes"); keygen.init(128);  // use 256 bit keys, need "unlimited strength" encryption policy files sun. byte[] key = keygen.generatekey().getencoded(); secretkeyspec skeyspec = new secretkeyspec(key, "aes");  // build initialization vector.  example zeros,  // value or generated using random number generator. byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; ivparameterspec ivspec = new ivparameterspec(iv);  // reinitialize cipher decryption cipher cipher = cipher.getinstance("aes/cbc/pkcs5padding"); cipher.init(cipher.decrypt_mode, skeyspec, ivspec);  // decrypt message byte[] decrypted = cipher.dofinal(line.getbytes()); system.out.println("plaintext: " + new string(decrypted) + "\n"); messagearea.append(name + ": " + decrypted + "\n"); messagearea.setcaretposition(messagearea.getdocument().getlength()); 

your problem has nothing cryptography. failing transfer data correctly between clients , server.

i'm sure out.println(encrypted) not want doing, although i'm not entirely clear since don't know type of out. nor should calling line.getbytes() in decryption code.

you should convert ciphertext non-lossy string form, such hexadecimal or base64. so, try:

out.println(datatypeconverter.printhexbinary(encrypted)); 

and

byte[] decrypted = cipher.dofinal(datatypeconverter.parsehexbinary(line));