com.motorola.iden.crypto
Class CipherSpi

java.lang.Object
  |
  +--com.motorola.iden.crypto.CipherSpi

Direct Known Subclasses:

AES, ARC4, DES, DESede, RC5, RSA

public abstract class CipherSpi

extends java.lang.Object

This class defines the Service Provider Interface (SPI) for the Cipher class. All the abstract methods in this class must be implemented by each cryptographic service provider who wishes to supply the implementation of a particular cipher algrithm

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See Also:

[Cipher]

Constructor Summary

CipherSpi()

Method Summary

protected abstract byte[]	engineDoFinal(byte[] input, int inputOffset, int inputLen) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
protected abstract int	engineGetBlockSize() Returns the block size (in bytes).
protected abstract byte[]	engineGetIV() Returns the initialization vector (IV) in a new buffer.
protected abstract void	engineInit(int opmode, Key key, AlgorithmParameterSpec params, SecureRandom random) Initializes this cipher with a key, a set of algorithm parameters, and a source of randomness.
protected abstract void	engineSetMode(java.lang.String mode) Sets the mode of this cipher.
protected abstract void	engineSetPadding(java.lang.String padding) Sets the padding mechanism of this cipher.
protected abstract byte[]	engineUpdate(byte[] input, int inputOffset, int inputLen) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.

Methods inherited from class java.lang.Object

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

Constructor Detail

CipherSpi

public CipherSpi()

Method Detail

engineSetMode

protected abstract void engineSetMode(java.lang.String mode)
                               throws NoSuchAlgorithmException

Sets the mode of this cipher.

Parameters:

mode - the cipher mode

Throws:

NoSuchAlgorithmException - if the requested cipher mode does not exist

engineSetPadding

protected abstract void engineSetPadding(java.lang.String padding)
                                  throws NoSuchPaddingException

Sets the padding mechanism of this cipher.

Parameters:

padding - the padding mechanism

Throws:

NoSuchPaddingException - if the requested padding mechanism does not exist

engineGetBlockSize

protected abstract int engineGetBlockSize()

Returns the block size (in bytes).

Returns:

the block size (in bytes), or 0 if the underlying algorithm is not a block cipher

engineGetIV

protected abstract byte[] engineGetIV()

Returns the initialization vector (IV) in a new buffer.

This is useful in the context of password-based encryption or decryption, where the IV is derived from a user-provided passphrase.

Returns:

the initialization vector in a new buffer, or null if the underlying algorithm does not use an IV, or if the IV has not yet been set.

engineInit

protected abstract void engineInit(int opmode,
                                   Key key,
                                   AlgorithmParameterSpec params,
                                   SecureRandom random)
                            throws InvalidKeyException,
                                   InvalidAlgorithmParameterException

Initializes this cipher with a key, a set of algorithm parameters, and a source of randomness.

The cipher is initialized for one of the following two operations: encryption or decryption,depending on the value of opmode.

If this cipher requires any algorithm parameters and params is null, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values).

If this cipher requires any random bytes, it will get them from random.

Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.

Parameters:

opmode - the operation mode of this cipher (this is one of the following: ENCRYPT_MODE, DECRYPT_MODE,

key - the encryption key

params - the algorithm parameters

random - the source of randomness

Throws:

InvalidKeyException - if the given key is inappropriate for initializing this cipher

InvalidAlgorithmParameterException - if the given algorithm parameters are inappropriate for this cipher, or if this cipher is being initialized for decryption and requires algorithm parameters and params is null.

engineUpdate

protected abstract byte[] engineUpdate(byte[] input,
                                       int inputOffset,
                                       int inputLen)

Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.

The first inputLen bytes in the input buffer, starting at inputOffset inclusive, are processed, and the result is stored in a new buffer.

Parameters:

input - the input buffer

inputOffset - the offset in input where the input starts

inputLen - the input length

Returns:

the new buffer with the result, or null if the underlying cipher is a block cipher and the input data is too short to result in a new block.

engineDoFinal

protected abstract byte[] engineDoFinal(byte[] input,
                                        int inputOffset,
                                        int inputLen)
                                 throws IllegalBlockSizeException,
                                        BadPaddingException

Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this cipher was initialized.

The first inputLen bytes in the input buffer, starting at inputOffset inclusive, and any input bytes that may have been buffered during a previous update operation, are processed, with padding (if requested) being applied. The result is stored in a new buffer.

A call to this method resets this cipher object to the state it was in when previously initialized via a call to engineInit. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to engineInit) more data.

Parameters:

input - the input buffer

inputOffset - the offset in input where the input starts

inputLen - the input length

Returns:

the new buffer with the result

Throws:

IllegalBlockSizeException - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size

BadPaddingException - if this cipher is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes