gnu.crypto.cipher

Interface IBlockCipher

public interface IBlockCipher extends 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:

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: 1.8 $

Field Summary
StringCIPHER_BLOCK_SIZE

Property name of the block size in which to operate a block cipher.

StringKEY_MATERIAL

Property name of the user-supplied key material.

Method Summary
IteratorblockSizes()

Returns an Iterator over the supported block sizes.

Objectclone()

Returns a clone of this instance.

intcurrentBlockSize()

Returns the currently set block size for this instance.

voiddecryptBlock(byte[] in, int inOffset, byte[] out, int outOffset)

Decrypts exactly one block of ciphertext.

intdefaultBlockSize()

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

intdefaultKeySize()

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

voidencryptBlock(byte[] in, int inOffset, byte[] out, int outOffset)

Encrypts exactly one block of plaintext.

voidinit(Map attributes)

Initialises the algorithm with designated attributes.

IteratorkeySizes()

Returns an Iterator over the supported key sizes.

Stringname()

Returns the canonical name of this instance.

voidreset()

Resets the algorithm instance for re-initialisation and use with other characteristics.

booleanselfTest()

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 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.

KEY_MATERIAL

public 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.

Method Detail

blockSizes

public 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.

clone

public Object clone()

Returns a clone of this instance.

Returns: a clone copy of this instance.

currentBlockSize

public int currentBlockSize()

Returns the currently set block size for this instance.

Returns: the current block size for this instance.

Throws: IllegalStateException if the instance is not initialised.

decryptBlock

public void decryptBlock(byte[] in, int inOffset, byte[] out, int outOffset)

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: IllegalStateException if the instance is not initialised.

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.

encryptBlock

public void encryptBlock(byte[] in, int inOffset, byte[] out, int outOffset)

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: IllegalStateException if the instance is not initialised.

init

public void init(Map attributes)

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: InvalidKeyException if the key data is invalid. IllegalStateException if the instance is already initialised.

See Also: KEY_MATERIAL CIPHER_BLOCK_SIZE

keySizes

public 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.

name

public String name()

Returns the canonical name of this instance.

Returns: the canonical name of this instance.

reset

public void reset()

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

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.

Copyright © 2001, 2002, 2003 Free Software Foundation, Inc. All Rights Reserved.