org.multibit.commons.crypto

Class AESUtils

java.lang.Object

org.multibit.commons.crypto.AESUtils

public class AESUtils
extends Object

Utility class to provide the following to BRIT API:

• Encryption and decryption using AES

Since:

0.0.1

Field Summary

Fields

Modifier and Type	Field and Description
static int	BLOCK_LENGTH The size of an AES block in bytes.
static int	KEY_LENGTH Key length in bytes.

Method Summary

Modifier and Type	Method and Description
static org.bouncycastle.crypto.params.KeyParameter	createAESKey(byte[] seed, byte[] salt) Create an AES 256 key given 20 bytes of entropy (e.g.
static byte[]	decrypt(byte[] encryptedBytes, org.bouncycastle.crypto.params.KeyParameter aesKey, byte[] initialisationVector) Decrypt bytes previously encrypted with this class.
static byte[]	encrypt(byte[] plainBytes, org.bouncycastle.crypto.params.KeyParameter aesKey, byte[] initialisationVector) Password based encryption using AES - CBC 256 bits.
static byte[]	generate160BitsOfEntropy(byte[] seed, byte[] salt) Generate 160 bits of entropy from the seed bytes.

Methods inherited from class java.lang.Object

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

Field Detail

KEY_LENGTH

public static final int KEY_LENGTH

Key length in bytes.

See Also:

Constant Field Values

BLOCK_LENGTH

public static final int BLOCK_LENGTH

The size of an AES block in bytes. This is also the length of the initialisation vector.

See Also:

Constant Field Values

Method Detail

encrypt

public static byte[] encrypt(byte[] plainBytes,
                             org.bouncycastle.crypto.params.KeyParameter aesKey,
                             byte[] initialisationVector)
                      throws org.bitcoinj.crypto.KeyCrypterException

Password based encryption using AES - CBC 256 bits.

Parameters:

plainBytes - The unencrypted bytes for encryption

aesKey - The AES key to use for encryption

initialisationVector - The initialisationVector to use whilst encrypting

Returns:

The encrypted bytes

Throws:

org.bitcoinj.crypto.KeyCrypterException

decrypt

public static byte[] decrypt(byte[] encryptedBytes,
                             org.bouncycastle.crypto.params.KeyParameter aesKey,
                             byte[] initialisationVector)
                      throws org.bitcoinj.crypto.KeyCrypterException

Decrypt bytes previously encrypted with this class.

Parameters:

encryptedBytes - The encrypted bytes required to decrypt

aesKey - The AES key to use for decryption

initialisationVector - The initialisationVector to use whilst decrypting

Returns:

The decrypted bytes

Throws:

org.bitcoinj.crypto.KeyCrypterException - if bytes could not be decoded to a valid key

generate160BitsOfEntropy

public static byte[] generate160BitsOfEntropy(byte[] seed,
                                              byte[] salt)

Generate 160 bits of entropy from the seed bytes. This uses a number of trapdoor functions and is tweakable by specifying a custom salt value

Parameters:

seed - seed bytes to use as 'credentials'/ initial value

salt - salt value used to customise trapdoor functions

Returns:

entropy 20 bytes of entropy

createAESKey

public static org.bouncycastle.crypto.params.KeyParameter createAESKey(byte[] seed,
                                                                       byte[] salt)
                                                                throws NoSuchAlgorithmException

Create an AES 256 key given 20 bytes of entropy (e.g. a walletId) and a salt byte array

Parameters:

seed - entropy, typically a wallet id or a credentials as bytes

salt - bytes, used as salt

Returns:

a KeyParameter suitable for AES encryption and decryption

Throws:

NoSuchAlgorithmException