Converting char array into byte array and back aga

Question

I'm looking to convert a Java char array to a byte array without creating an intermediate String, as the char array contains a password. I've looked up a couple of methods, but they all seem to fail:

char[] password = "password".toCharArray();

byte[] passwordBytes1 = new byte[password.length*2];
ByteBuffer.wrap(passwordBytes1).asCharBuffer().put(password);

byte[] passwordBytes2 = new byte[password.length*2];
for(int i=0; i<password.length; i++) {
    passwordBytes2[2*i] = (byte) ((password[i]&0xFF00)>>8); 
    passwordBytes2[2*i+1] = (byte) (password[i]&0x00FF); 
}

String passwordAsString = new String(password);
String passwordBytes1AsString = new String(passwordBytes1);
String passwordBytes2AsString = new String(passwordBytes2);

System.out.println(passwordAsString);
System.out.println(passwordBytes1AsString);
System.out.println(passwordBytes2AsString);
assertTrue(passwordAsString.equals(passwordBytes1) || passwordAsString.equals(passwordBytes2));

The assertion always fails (and, critically, when the code is used in production, the password is rejected), yet the print statements print out password three times. Why are passwordBytes1AsString and passwordBytes2AsString different from passwordAsString, yet appear identical? Am I missing out a null terminator or something? What can I do to make the conversion and unconversion work?

Answer 1

I would do is use a loop to convert to bytes and another to conver back to char.

char[] chars = "password".toCharArray();
byte[] bytes = new byte[chars.length*2];
for(int i=0;i<chars.length;i++) {
   bytes[i*2] = (byte) (chars[i] >> 8);
   bytes[i*2+1] = (byte) chars[i];
}
char[] chars2 = new char[bytes.length/2];
for(int i=0;i<chars2.length;i++) 
   chars2[i] = (char) ((bytes[i*2] << 8) + (bytes[i*2+1] & 0xFF));
String password = new String(chars2);

Answer 2

You should make use of getBytes() instead of toCharArray()

Replace the line

char[] password = "password".toCharArray();

with

byte[] password = "password".getBytes();