com.absio.crypto.kdf

Class PBKDF2Helper

java.lang.Object

com.absio.crypto.kdf.PBKDF2Helper

public class PBKDF2Helper
extends Object

This is a helper class to deliver both PBKDF2 key generation and formatted encryption and decryption methods. The format of the data is salt length + salt + iv length + iv + encrypted data length + encrypted data. Note: this uses PBKDF2 for the key generation and CipherHelper for the encrypt/decrypt operations.

Constructor Summary

Constructors

Constructor and Description
PBKDF2Helper() This will create a helper using MacAlgorithm.HMACSHA384, CipherTransformation.AES_CTR_NOPADDING, AESKeyStrength.AES256 and UTF-8 for the encoding.
PBKDF2Helper(MacAlgorithm macAlgorithm, CipherTransformation transformation, AESKeyStrength keyStrength, String encoding) This will create a helper with the given settings for key generation and encryption.

Method Summary

Modifier and Type	Method and Description
byte[]	decryptFromFormat(byte[] formattedData, String password, int iterationCount) This will decrypt data that was encrypted with a PBKDF2 derived key where the data is in the following format: salt length + salt + iv length + iv + encrypted data length + encrypted data.
byte[]	encryptToFormat(byte[] data, byte[] salt, String password, int iterationCount) This will encrypt data with a PBKDF2 derived key and then format the data as follows: salt length + salt + iv length + iv + encrypted data length + encrypted data.
byte[]	encryptToFormat(byte[] data, int saltLength, String password, int iterationCount) This will encrypt data with a PBKDF2 derived key and then format the data as follows: salt length + salt + iv length + iv + encrypted data length + encrypted data.
byte[]	generateDerivedKey(String password, byte[] salt, int iterationCount) Generate the derived PBKDF2 key using the password, salt and iteration count.

Methods inherited from class java.lang.Object

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

Constructor Detail

PBKDF2Helper

public PBKDF2Helper()
             throws NoSuchPaddingException,
                    NoSuchAlgorithmException

This will create a helper using MacAlgorithm.HMACSHA384, CipherTransformation.AES_CTR_NOPADDING, AESKeyStrength.AES256 and UTF-8 for the encoding.

Throws:

NoSuchPaddingException - thrown if padding not supported

NoSuchAlgorithmException - thrown if algorithm not supported

PBKDF2Helper

public PBKDF2Helper(MacAlgorithm macAlgorithm,
                    CipherTransformation transformation,
                    AESKeyStrength keyStrength,
                    String encoding)
             throws NoSuchAlgorithmException,
                    NoSuchPaddingException

This will create a helper with the given settings for key generation and encryption. Note: encryption and decryption are done to and from a specific format.

Parameters:

macAlgorithm - the name of the MAC algorithm to use

transformation - the transformation to use for encrypting data

keyStrength - the key strength for determining the key size in bytes

encoding - the encoding to use

Throws:

NoSuchPaddingException - thrown if padding not supported

NoSuchAlgorithmException - thrown if algorithm not supported

Method Detail

decryptFromFormat

public byte[] decryptFromFormat(byte[] formattedData,
                                String password,
                                int iterationCount)
                         throws IOException,
                                IllegalBlockSizeException,
                                InvalidKeyException,
                                InvalidAlgorithmParameterException,
                                BadPaddingException

This will decrypt data that was encrypted with a PBKDF2 derived key where the data is in the following format: salt length + salt + iv length + iv + encrypted data length + encrypted data. Note: this uses CipherHelper for the decryption and PBKDF2 for the key generation

Parameters:

formattedData - the data in the following format: salt length + salt + iv length + iv + encrypted data length + encrypted data

password - the password used to derive the key

iterationCount - the iteration count used to derive the key

Returns:

the decrypted data

Throws:

IOException - thrown if there was an error reading in the formatted data

IllegalBlockSizeException - thrown if the cipher block size is wrong

InvalidKeyException - thrown if there is an issue with the key

InvalidAlgorithmParameterException - thrown if the cipher algorithm is not supported

BadPaddingException - thrown if the cipher padding is not supported

encryptToFormat

public byte[] encryptToFormat(byte[] data,
                              int saltLength,
                              String password,
                              int iterationCount)
                       throws IOException,
                              IllegalBlockSizeException,
                              BadPaddingException,
                              InvalidAlgorithmParameterException,
                              InvalidKeyException

This will encrypt data with a PBKDF2 derived key and then format the data as follows: salt length + salt + iv length + iv + encrypted data length + encrypted data. For this call the salt is created from random bytes. Note: this uses CipherHelper for the encryption and PBKDF2 for the key generation

Parameters:

data - the data to encrypt

saltLength - the length of the salt to create with random data

password - the password used to derive the key

iterationCount - the iteration count used to derive the key

Returns:

the encrypted data formatted as follows: salt length + salt + iv length + iv + encrypted data length + encrypted data

Throws:

IOException - thrown if there was an error reading in the formatted data

IllegalBlockSizeException - thrown if the cipher block size is wrong

InvalidKeyException - thrown if there is an issue with the key

InvalidAlgorithmParameterException - thrown if the cipher algorithm is not supported

BadPaddingException - thrown if the cipher padding is not supported

encryptToFormat

public byte[] encryptToFormat(byte[] data,
                              byte[] salt,
                              String password,
                              int iterationCount)
                       throws IOException,
                              IllegalBlockSizeException,
                              BadPaddingException,
                              InvalidAlgorithmParameterException,
                              InvalidKeyException

This will encrypt data with a PBKDF2 derived key and then format the data as follows: salt length + salt + iv length + iv + encrypted data length + encrypted data. Note: this uses CipherHelper for the encryption and PBKDF2 for the key generation

Parameters:

data - the data to encrypt

salt - the salt to use when deriving the key

password - the password used to derive the key

iterationCount - the iteration count used to derive the key

Returns:

the encrypted data formatted as follows: salt length + salt + iv length + iv + encrypted data length + encrypted data

Throws:

IOException - thrown if there was an error reading in the formatted data

IllegalBlockSizeException - thrown if the cipher block size is wrong

InvalidKeyException - thrown if there is an issue with the key

InvalidAlgorithmParameterException - thrown if the cipher algorithm is not supported

BadPaddingException - thrown if the cipher padding is not supported

generateDerivedKey

public byte[] generateDerivedKey(String password,
                                 byte[] salt,
                                 int iterationCount)
                          throws InvalidKeyException,
                                 UnsupportedEncodingException

Generate the derived PBKDF2 key using the password, salt and iteration count. Note: PBKDF2 is used to derive the key.

Parameters:

password - the password

salt - the salt

iterationCount - the iteration count

Returns:

the derived PBDKF2 key

Throws:

InvalidKeyException - thrown if an error occurred while deriving the key

UnsupportedEncodingException - thrown if the provided encoding is not supported