org.daveware.passwordmaker

Class SecureByteArray

java.lang.Object

org.daveware.passwordmaker.SecureByteArray

public class SecureByteArray
extends Object

Provides an array capable of erasing the contents upon request.

It's a very bad idea to store passwords in a java.lang.String object because once that object is created, you cannot guarantee that the contents will be erased. You can't get at the actual bytes inside the String object. Thus you cannot reset all the bytes to 0.

This object stores a plain array of bytes allowing the data to be erased back to 0 at any given time.

ALWWAYS reset your password storage variables when you are through with them and be very wary of the stack.

Author:

Dave Marotti

Constructor Summary

Constructors

Constructor and Description
SecureByteArray()
SecureByteArray(byte[] bytes)
SecureByteArray(char[] chars)
SecureByteArray(int size)
SecureByteArray(SecureByteArray copy)
SecureByteArray(String str) Creates the object from a string (don't pass passwords in this way).

Method Summary

Methods

Modifier and Type	Method and Description
void	append(SecureByteArray arr) Appends another SecureByteArray to this one.
void	erase() Erases the data in this array by writing a pattern over every element of the array.
byte	getByteAt(int index) Obtains the byte at an index.
byte[]	getData() Returns a reference to the data.
void	prepend(SecureByteArray arr) Prepends this array with another SecureByteArray.
void	replace(SecureByteArray arr) Replaces the contents of this array with a copy of those in arr, resizing the array as needed.
void	resize(int size, boolean retainData) Resizes the array, optionally keeping the old data.
void	setByteAt(int index, byte c) Sets the byte at an index.
int	size() Gets the size of this array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SecureByteArray

public SecureByteArray()

SecureByteArray

public SecureByteArray(int size)

SecureByteArray

public SecureByteArray(byte[] bytes)

SecureByteArray

public SecureByteArray(char[] chars)

SecureByteArray

public SecureByteArray(SecureByteArray copy)

SecureByteArray

public SecureByteArray(String str)

Creates the object from a string (don't pass passwords in this way).

Parameters:

str - The string object to get the data from.

Method Detail

append

public void append(SecureByteArray arr)
            throws Exception

Appends another SecureByteArray to this one.

Parameters:

arr - The array to append.

Throws:

Exception - Upon size problems. (lol)

erase

public void erase()

Erases the data in this array by writing a pattern over every element of the array.

The pattern part probably isn't needed and probably doesn't do anything but it's there anyway. The important part is to reset all the elements back to 0.

getByteAt

public byte getByteAt(int index)
               throws ArrayIndexOutOfBoundsException

Obtains the byte at an index.

Parameters:

index - The index to obtain the byte at.

Returns:

The byte at the index.

Throws:

ArrayIndexOutOfBoundsException - Upon bad index.

getData

public byte[] getData()

Returns a reference to the data.

Returns:

a reference to the data.

prepend

public void prepend(SecureByteArray arr)
             throws Exception

Prepends this array with another SecureByteArray.

Parameters:

arr - The array to prepend.

Throws:

Exception - Upon size problems. (lol)

replace

public void replace(SecureByteArray arr)
             throws Exception

Replaces the contents of this array with a copy of those in arr, resizing the array as needed.

Parameters:

arr - The copy to use.

Throws:

Exception

resize

public void resize(int size,
          boolean retainData)
            throws Exception

Resizes the array, optionally keeping the old data.

Parameters:

size - The new size of the array. This must be 1 or larger.

retainData - Whether or not to keep the old data.

Throws:

Exception - If the size is 0 or less.

setByteAt

public void setByteAt(int index,
             byte c)
               throws ArrayIndexOutOfBoundsException

Sets the byte at an index.

Parameters:

index - The index to set at.

c - The byte to set.

Throws:

ArrayIndexOutOfBoundsException - Upon bad index.

size

public int size()

Gets the size of this array.

Returns:

The size of the array.