at.favre.lib.armadillo

Class PBKDF2KeyStretcher

java.lang.Object

at.favre.lib.armadillo.PBKDF2KeyStretcher

All Implemented Interfaces:

KeyStretchingFunction

public final class PBKDF2KeyStretcher
extends java.lang.Object
implements KeyStretchingFunction

In cryptography, PBKDF2 (Password-Based Key Derivation Function 2) are key derivation functions with a sliding computational cost, aimed to reduce the vulnerability of encrypted keys to brute force attacks. PBKDF2 is part of RSA Laboratories' Public-Key Cryptography Standards (PKCS) series, specifically PKCS #5 v2.0, also published as Internet Engineering Task Force's RFC 2898.

This uses SHA1 as the underlying cryptographic hash functions, since SHA256+ are usually not provided by standard JCA providers in Android.

Since:

19.12.2017

Constructor Summary

Constructors

Constructor and Description
PBKDF2KeyStretcher() Create a new instance with default iteration count (see PBKDF2_DEFAULT_ITERATIONS
PBKDF2KeyStretcher(int iterations, java.security.Provider provider) Creates a new instance.

Method Summary

Modifier and Type	Method and Description
byte[]	stretch(byte[] salt, char[] password, int outLengthByte) Derives and stretches the given password with given salt to desired out length.

Methods inherited from class java.lang.Object

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

Constructor Detail

PBKDF2KeyStretcher

public PBKDF2KeyStretcher()

Create a new instance with default iteration count (see PBKDF2_DEFAULT_ITERATIONS

PBKDF2KeyStretcher

public PBKDF2KeyStretcher(int iterations,
                          java.security.Provider provider)

Creates a new instance. See https://cryptosense.com/parameter-choice-for-pbkdf2/ for idea on what iteration count to choose

Parameters:

iterations - computational cost

provider - optional security provider (might be null if default should be chosen)

Method Detail

stretch

public byte[] stretch(byte[] salt,
                      char[] password,
                      int outLengthByte)

Description copied from interface: KeyStretchingFunction

Derives and stretches the given password with given salt to desired out length.

Specified by:

stretch in interface KeyStretchingFunction

Parameters:

salt - to use when deriving/stretching the password

password - to stretch

outLengthByte - required out length byte

Returns:

byte array with length of outLengthByte