gnu.crypto.cipher
Interface IBlockCipher

All Superinterfaces:

java.lang.Cloneable

All Known Subinterfaces:

IMode

All Known Implementing Classes:

BaseCipher, BaseMode

public interface IBlockCipher

extends java.lang.Cloneable

The basic visible methods of any symmetric key block cipher.

A symmetric key block cipher is a function that maps n-bit plaintext blocks to n-bit ciphertext blocks; n being the cipher's block size. This encryption function is parameterised by a k-bit key, and is invertible. Its inverse is the decryption function.

Possible initialisation values for an instance of this type are:

• The block size in which to operate this block cipher instance. This value is optional, if unspecified, the block cipher's default block size shall be used.
• The byte array containing the user supplied key material to use for generating the cipher's session key(s). This value is mandatory and should be included in the initialisation parameters. If it isn't, an IllegalStateException will be thrown if any method, other than reset() is invoked on the instance. Furthermore, the size of this key material shall be taken as an indication on the key size in which to operate this instance.

IMPLEMENTATION NOTE: Although all the concrete classes in this package implement the Cloneable interface, it is important to note here that such an operation DOES NOT clone any session key material that may have been used in initialising the source cipher (the instance to be cloned). Instead a clone of an already initialised cipher is another instance that operates with the same block size but without any knowledge of neither key material nor key size.

Version:

$Revision: 1.2 $

Field Summary

static java.lang.String	CIPHER_BLOCK_SIZE Property name of the block size in which to operate a block cipher.
static java.lang.String	KEY_MATERIAL Property name of the user-supplied key material.

Method Summary

java.util.Iterator	blockSizes() Returns an Iterator over the supported block sizes.
java.lang.Object	clone() Returns a clone of this instance.
int	currentBlockSize() Returns the currently set block size for this instance.
void	decryptBlock(byte[] in, int inOffset, byte[] out, int outOffset) Decrypts exactly one block of ciphertext.
int	defaultBlockSize() Returns the default value, in bytes, of the algorithm's block size.
int	defaultKeySize() Returns the default value, in bytes, of the algorithm's key size.
void	encryptBlock(byte[] in, int inOffset, byte[] out, int outOffset) Encrypts exactly one block of plaintext.
void	init(java.util.Map attributes) Initialises the algorithm with designated attributes.
java.util.Iterator	keySizes() Returns an Iterator over the supported key sizes.
java.lang.String	name() Returns the canonical name of this instance.
void	reset() Resets the algorithm instance for re-initialisation and use with other characteristics.
boolean	selfTest() A correctness test that consists of basic symmetric encryption / decryption test(s) for all supported block and key sizes, as well as one (1) variable key Known Answer Test (KAT).

Field Detail

CIPHER_BLOCK_SIZE

public static final java.lang.String CIPHER_BLOCK_SIZE

Property name of the block size in which to operate a block cipher. The value associated with this property name is taken to be an Integer.

See Also:

Constant Field Values

KEY_MATERIAL

public static final java.lang.String KEY_MATERIAL

Property name of the user-supplied key material. The value associated to this property name is taken to be a byte array.

See Also:

Constant Field Values

Method Detail

name

public java.lang.String name()

Returns the canonical name of this instance.

Returns:

the canonical name of this instance.

defaultBlockSize

public int defaultBlockSize()

Returns the default value, in bytes, of the algorithm's block size.

Returns:

the default value, in bytes, of the algorithm's block size.

defaultKeySize

public int defaultKeySize()

Returns the default value, in bytes, of the algorithm's key size.

Returns:

the default value, in bytes, of the algorithm's key size.

blockSizes

public java.util.Iterator blockSizes()

Returns an Iterator over the supported block sizes. Each element returned by this object is an Integer.

Returns:

an Iterator over the supported block sizes.

keySizes

public java.util.Iterator keySizes()

Returns an Iterator over the supported key sizes. Each element returned by this object is an Integer.

Returns:

an Iterator over the supported key sizes.

clone

public java.lang.Object clone()

Returns a clone of this instance.

Returns:

a clone copy of this instance.

init

public void init(java.util.Map attributes)
          throws java.security.InvalidKeyException,
                 java.lang.IllegalStateException

Initialises the algorithm with designated attributes. Permissible names and values are described in the class documentation above.

Parameters:

attributes - a set of name-value pairs that describes the desired future behaviour of this instance.

Throws:

java.security.InvalidKeyException - if the key data is invalid.

java.lang.IllegalStateException - if the instance is already initialised.

See Also:

KEY_MATERIAL, CIPHER_BLOCK_SIZE

currentBlockSize

public int currentBlockSize()
                     throws java.lang.IllegalStateException

Returns the currently set block size for this instance.

Returns:

the current block size for this instance.

Throws:

java.lang.IllegalStateException - if the instance is not initialised.

reset

public void reset()

Resets the algorithm instance for re-initialisation and use with other characteristics. This method always succeeds.

encryptBlock

public void encryptBlock(byte[] in,
                         int inOffset,
                         byte[] out,
                         int outOffset)
                  throws java.lang.IllegalStateException

Encrypts exactly one block of plaintext.

Parameters:

in - the plaintext.

inOffset - index of in from which to start considering data.

out - the ciphertext.

outOffset - index of out from which to store result.

Throws:

java.lang.IllegalStateException - if the instance is not initialised.

decryptBlock

public void decryptBlock(byte[] in,
                         int inOffset,
                         byte[] out,
                         int outOffset)
                  throws java.lang.IllegalStateException

Decrypts exactly one block of ciphertext.

Parameters:

in - the plaintext.

inOffset - index of in from which to start considering data.

out - the ciphertext.

outOffset - index of out from which to store result.

Throws:

java.lang.IllegalStateException - if the instance is not initialised.

selfTest

public boolean selfTest()

A correctness test that consists of basic symmetric encryption / decryption test(s) for all supported block and key sizes, as well as one (1) variable key Known Answer Test (KAT).

Returns:

true if the implementation passes simple correctness tests. Returns false otherwise.