info.pppc.base.security.key

Class AESSymmetricKey

java.lang.Object

info.pppc.base.security.key.AESSymmetricKey

All Implemented Interfaces:

IPrivateKey, IPublicKey, ISymEncryptionKey, ISymmetricKey

public class AESSymmetricKey
extends java.lang.Object
implements ISymEncryptionKey

This class implements a symmetric AES encryption/decryption. If you also need to create signatures, have a look at the HMACSymmetricKey.

Author:

WA

Field Summary

Fields

Modifier and Type	Field and Description
static int	STANDARD_AES_KEY_AND_BLOCK_SIZE Standard key size is 128 bits.

Fields inherited from interface info.pppc.base.security.ISymmetricKey

TIMESTAMP_MANUAL, TIMESTAMP_MISSING

Constructor Summary

Constructors

Constructor and Description
AESSymmetricKey(byte[] key, long timestamp) Creates a new AES key that can be used for encryption or decryption
AESSymmetricKey(byte[] key, long timestamp, SystemID systemID) Creates a new AES key that can be used for encryption or decryption

Method Summary

Methods

Modifier and Type	Method and Description
static void	checkAESKey(byte[] key) Checks if the key supplied could be used as a valid AES key (ie. it conforms to the key sizes)
byte[]	createSignature(byte[] message) Since this key is not for signing, a runtime exception will be thrown.
byte[]	decryptMessage(byte[] message) Decrypts an encrypted message (with this private key).
byte[]	encryptMessage(byte[] input) Encrypts a message with this public key.
boolean	forEncryption() This key can be used for encryption and decryption, so this method will return true.
boolean	forSigning() This key cannot be used for signing, so this method will return false.
SystemID	getCorrespondingSystemID()
byte[]	getKey() Get the key as a byte array.
long	getTimestamp() Returns the time stamp of a symmetric key or TIMESTAMP_MISSING, if there is no entry for the key.
boolean	verifySignature(byte[] message, byte[] signature) Since this key is not for signing, a runtime exception will be thrown.

Methods inherited from class java.lang.Object

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

Methods inherited from interface info.pppc.base.security.IPublicKey

equals

Methods inherited from interface info.pppc.base.security.IPrivateKey

equals

Field Detail

STANDARD_AES_KEY_AND_BLOCK_SIZE

public static final int STANDARD_AES_KEY_AND_BLOCK_SIZE

Standard key size is 128 bits. The block size is ALWAYS 128 bits, even by using keys with 192 or 256 bits.

See Also:

Constant Field Values

Constructor Detail

AESSymmetricKey

public AESSymmetricKey(byte[] key,
               long timestamp,
               SystemID systemID)
                throws java.lang.IllegalArgumentException

Creates a new AES key that can be used for encryption or decryption

Parameters:

key - A secret key as byte array, only keys of the size described in keySizes are allowed

Throws:

java.lang.IllegalArgumentException - If the key does not conform to the specified key sizes, this exception is thrown

AESSymmetricKey

public AESSymmetricKey(byte[] key,
               long timestamp)
                throws java.lang.IllegalArgumentException

Creates a new AES key that can be used for encryption or decryption

Parameters:

key - A secret key as byte array, only keys of the size described in keySizes are allowed

Throws:

java.lang.IllegalArgumentException - If the key does not conform to the specified key sizes, this exception is thrown

Method Detail

checkAESKey

public static void checkAESKey(byte[] key)
                        throws java.lang.IllegalArgumentException

Checks if the key supplied could be used as a valid AES key (ie. it conforms to the key sizes)

Parameters:

key - The key that should be checked as byte array

Throws:

java.lang.IllegalArgumentException - If the key is not a valid AES key

forEncryption

public boolean forEncryption()

This key can be used for encryption and decryption, so this method will return true.

If this symmetric key can be used for encryption, this method will return true.

Specified by:

forEncryption in interface ISymmetricKey

Returns:

True, if this key can be used for encryption

forSigning

public boolean forSigning()

This key cannot be used for signing, so this method will return false.

If this symmetric key can be used to create signatures, this method will return true.

Specified by:

forSigning in interface ISymmetricKey

Returns:

True, if this key can be used to create signatures

encryptMessage

public byte[] encryptMessage(byte[] input)
                      throws java.io.IOException

Encrypts a message with this public key. The encryption could include a header in the returned message, to use hybrid encryption mechanisms.
A message will be encrypted using both asymmetric and symmetric encryption, if the message size exceeds the block size of the asymmetric encryption.
If this is a symmetric key, then always symmetric encryption is used.

Specified by:

encryptMessage in interface IPublicKey

Parameters:

input - The message which should be encrypted

Returns:

The encrypted message, maybe containing a header, as described above

Throws:

java.io.IOException - If not enough memory is available or if a key could not be read, this exception occurs

verifySignature

public boolean verifySignature(byte[] message,
                      byte[] signature)

Since this key is not for signing, a runtime exception will be thrown.

Specified by:

verifySignature in interface IPublicKey

Parameters:

message - A runtime exception will be thrown.

signature - A runtime exception will be thrown.

Returns:

A runtime exception will be thrown.

createSignature

public byte[] createSignature(byte[] message)

Since this key is not for signing, a runtime exception will be thrown.

Specified by:

createSignature in interface IPrivateKey

Parameters:

message - A runtime exception will be thrown.

Returns:

A runtime exception will be thrown.

decryptMessage

public byte[] decryptMessage(byte[] message)
                      throws java.lang.IndexOutOfBoundsException

Decrypts an encrypted message (with this private key).

Specified by:

decryptMessage in interface IPrivateKey

Parameters:

message - The encrypted message, which should be decrypted

Returns:

The decrypted message, if the message could be successfully decrypted or null otherwise

Throws:

java.lang.IndexOutOfBoundsException

getTimestamp

public long getTimestamp()

Description copied from interface: ISymmetricKey

Returns the time stamp of a symmetric key or TIMESTAMP_MISSING, if there is no entry for the key.

Specified by:

getTimestamp in interface ISymmetricKey

Returns:

The time stamp of the key.

getKey

public byte[] getKey()

Description copied from interface: ISymmetricKey

Get the key as a byte array.

Specified by:

getKey in interface ISymmetricKey

Returns:

The key of this implementation of ISymmetricKey.

getCorrespondingSystemID

public SystemID getCorrespondingSystemID()

Specified by:

getCorrespondingSystemID in interface ISymmetricKey