com.absio.crypto.cipher

Class CipherHelper

java.lang.Object

com.absio.crypto.cipher.CipherHelper

public class CipherHelper
extends Object

Use this helper class to assist with cipher key and encryption operations. It uses the JCE Cipher class to accomplish most of these operations. The helper works with a set CipherTransformation which is defined at creation.

Constructor Summary

Constructors

Constructor and Description
CipherHelper() Creates a helper with CipherTransformation.DEFAULT as the transformation.
CipherHelper(CipherTransformation transformation) Create a helper with the given transformation.

Method Summary

Modifier and Type	Method and Description
byte[]	decrypt(byte[] key, byte[] iv, byte[] ciphertext) This will decrypt the ciphertext using the given key and iv.
EncryptionResults	encrypt(byte[] plaintext) This will encrypt the plaintext using the given key and iv.
byte[]	encrypt(byte[] key, byte[] iv, byte[] plaintext) This will encrypt the plaintext using the given key and iv.
byte[]	generateIV() Using the block size of the cipher and the mode of the transformation this will generate an initialization vector.
byte[]	generateKey() This will generate a symmetric key using AESKeyStrength.DEFAULT for determining the size.
byte[]	generateKey(AESKeyStrength keyStrength) This will generate a symmetric key using the given AESKeyStrength for determining the size.
byte[]	generateKey(int keySize) This will generate a symmetric key of the given size using the algorithm of the helper's defined CipherTransformation.

Methods inherited from class java.lang.Object

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

Constructor Detail

CipherHelper

public CipherHelper()
             throws NoSuchAlgorithmException,
                    NoSuchPaddingException

Creates a helper with CipherTransformation.DEFAULT as the transformation.

Throws:

NoSuchAlgorithmException - thrown if the algorithm in the transformation is not supported

NoSuchPaddingException - thrown if the padding in the transformation is not supported

CipherHelper

public CipherHelper(CipherTransformation transformation)
             throws NoSuchPaddingException,
                    NoSuchAlgorithmException

Create a helper with the given transformation.

Parameters:

transformation - the transformation to use in this helper

Throws:

NoSuchAlgorithmException - thrown if the algorithm in the transformation is not supported

NoSuchPaddingException - thrown if the padding in the transformation is not supported

Method Detail

decrypt

public byte[] decrypt(byte[] key,
                      byte[] iv,
                      byte[] ciphertext)
               throws BadPaddingException,
                      IllegalBlockSizeException,
                      InvalidAlgorithmParameterException,
                      InvalidKeyException

This will decrypt the ciphertext using the given key and iv. The Cipher created using the information from the CipherTransformation is used for the decryption.

Parameters:

key - the key to use for decrypting the data

iv - the iv to use for decrypting the data

ciphertext - the data to decrypt

Returns:

the decrypted data

Throws:

BadPaddingException - thrown if the padding in the transformation is not supported

IllegalBlockSizeException - thrown if the block size in the transformation is not supported

InvalidAlgorithmParameterException - thrown if the algorithm in the transformation is not supported

InvalidKeyException - thrown if the key is not valid

encrypt

public byte[] encrypt(byte[] key,
                      byte[] iv,
                      byte[] plaintext)
               throws InvalidAlgorithmParameterException,
                      InvalidKeyException,
                      BadPaddingException,
                      IllegalBlockSizeException

This will encrypt the plaintext using the given key and iv. The Cipher created using the information from the CipherTransformation is used for the encryption.

Parameters:

key - the key to use for encrypting the data

iv - the iv to use for encrypting the data

plaintext - the data to encrypt

Returns:

the encrypted data

Throws:

InvalidAlgorithmParameterException - thrown if the algorithm in the transformation is not supported

InvalidKeyException - thrown if the key is not valid

BadPaddingException - thrown if the padding in the transformation is not supported

IllegalBlockSizeException - thrown if the block size in the transformation is not supported

encrypt

public EncryptionResults encrypt(byte[] plaintext)
                          throws InvalidAlgorithmParameterException,
                                 InvalidKeyException,
                                 BadPaddingException,
                                 IllegalBlockSizeException,
                                 NoSuchAlgorithmException

This will encrypt the plaintext using the given key and iv. The Cipher created using the information from the CipherTransformation is used for the encryption.

Parameters:

plaintext - the data to encrypt

Returns:

the encryption results

Throws:

InvalidAlgorithmParameterException - thrown if the algorithm in the transformation is not supported

InvalidKeyException - thrown if the key is not valid

BadPaddingException - thrown if the padding in the transformation is not supported

IllegalBlockSizeException - thrown if the block size in the transformation is not supported

NoSuchAlgorithmException - thrown if the algorithm of the transformation is not supported

generateIV

public byte[] generateIV()

Using the block size of the cipher and the mode of the transformation this will generate an initialization vector. For CTR mode, a counter initialization vector is created. Otherwise the initialization vector will be random bytes (the block size long).

Returns:

the initialization vector

generateKey

public byte[] generateKey()
                   throws NoSuchAlgorithmException

This will generate a symmetric key using AESKeyStrength.DEFAULT for determining the size.

Note: this will only work if the helper's transformation has an algorithm of AES.

Returns:

the generated symmetric key

Throws:

NoSuchAlgorithmException - thrown if the algorithm of the transformation is not supported

generateKey

public byte[] generateKey(int keySize)
                   throws NoSuchAlgorithmException

This will generate a symmetric key of the given size using the algorithm of the helper's defined CipherTransformation.

Parameters:

keySize - the symmetric key size in bits

Returns:

the generated symmetric key

Throws:

NoSuchAlgorithmException - thrown if the algorithm of the transformation is not supported

generateKey

public byte[] generateKey(AESKeyStrength keyStrength)
                   throws NoSuchAlgorithmException

This will generate a symmetric key using the given AESKeyStrength for determining the size.

Note: this will only work if the helper's transformation has an algorithm of AES.

Parameters:

keyStrength - the AESKeyStrength to use when generating the key - used to get the key size in bits

Returns:

the generated symmetric key

Throws:

NoSuchAlgorithmException - thrown if the algorithm of the transformation is not supported