Package dev.brachtendorf

Class CryptoUtil

java.lang.Object

dev.brachtendorf.CryptoUtil

public class CryptoUtil
extends Object

Crypto utilities used to encrypt and decrypt data.

NO WARRANTY or liability that the functions are used correctly. If you work with highly sensitive data look for someone who actually knows their way around cryptographic code.

Author:

Kilian

Constructor Summary

Constructors

Constructor	Description
CryptoUtil()

Method Summary

Modifier and Type	Method	Description
static String	decrypt(SecretKey key, String encrypted)
static SecretKey	deriveKey(char[] password)	Derives a 128 bit AES key from a given password useful for further encryption usage.
static SecretKey	deriveKey(char[] password, byte[] salt, int keyLength)	Derives an AES key from a given password useful for further encryption usage.
static String	encryptAES(SecretKey key, String text)	Encrypt a given string with AES/CBC/PKCS5PADDING cipher.

Methods inherited from class java.lang.Object

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

Constructor Detail

CryptoUtil

public CryptoUtil()

Method Detail

deriveKey

public static SecretKey deriveKey(char[] password,
                                  byte[] salt,
                                  int keyLength)
                           throws InvalidKeySpecException

Derives an AES key from a given password useful for further encryption usage. Key derivation is needed due to AES requiring an x bit key from a short password sequence

Parameters:

password - User defined password

salt - Salt added to the password

keyLength - bit key length. Has to be a 2 complement 64 128 256 525 ...

Returns:

A secret key used for encryption and decryption operations

Throws:

InvalidKeySpecException - if the given key specificationis inappropriate for this secret-key

Since:

1.0.0 com.github.kilianB

See Also:

Based on https://stackoverflow.com/questions/992019/java-256-bit-aes-password-based-encryption/992413

deriveKey

public static SecretKey deriveKey(char[] password)

Derives a 128 bit AES key from a given password useful for further encryption usage.

Parameters:

password - The password used to create the key

Returns:

A secret key used for encryption and decryption operations

Since:

1.0.0 com.github.kilianB

See Also:

Based on https://stackoverflow.com/questions/992019/java-256-bit-aes-password-based-encryption/992413

encryptAES

public static String encryptAES(SecretKey key,
                                String text)
                         throws Exception

Encrypt a given string with AES/CBC/PKCS5PADDING cipher. The returned string is base64 encoded. The first 16 bytes are holds the init vector enabling persistent storage and reconstruction at a later stage.

Parameters:

key - they key used to encrypt the data

text - the data t encrypt

Returns:

the encrypted text with the init vector encoded as base64 string

Throws:

Exception - if an exception occurs

Since:

1.0.0 com.github.kilianB

See Also:

Partially based on: https://stackoverflow.com/questions/15554296/simple-java-aes-encrypt-decrypt-example

decrypt

public static String decrypt(SecretKey key,
                             String encrypted)
                      throws Exception

Parameters:

key - used to decrypt the data. A key with the same settings during encryption should be used to retrieve useable results

encrypted - the base64 representation of the encrypted text as returned by encryptAES(SecretKey, String)

Returns:

the decrypted text

Throws:

Exception - if an Exception occurs

Since:

1.0.0 com.github.kilianB