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Class au.net.aba.crypto.provider.BlockCipher

java.lang.Object
   |
   +----javax.crypto.CipherSpi
           |
           +----au.net.aba.crypto.provider.BlockCipher

public abstract class BlockCipher

extends CipherSpi

This class supports PKCS#5 and NoPadding, as well as supporting ECB and CBC modes. The standard block size is 8.

To implement a new block cipher it is necessary to implement the three abstract methods that re-key the cipher, do encryption and decryption using the current. It may also be necessary to override the engineSetMode method if CBC or ECB are not supported. If different padding mechanisms are used engineSetPadding may be overridden (in which case it may also be necessary to override engineGetOutputSize). For block sizes other than 8 engineGetBlockSize should be overridden. Finally if the algorithm supports AlgorithmParameterSpec just override the engineInit method that accepts those parameters.

BLOCK_SIZE

buffer

bufferPos

CBC

cbcV

ECB

firstBlock

ident

ivec

ivEncrypted

ivInline

key

mode

paddedStream

random

streamMode

BlockCipher()

decryptBlock(byte[], int, int, byte[], int)

Decrypt the given block starting at the given offset and place the result in the provided buffer starting at the given offset.

encryptBlock(byte[], int, int, byte[], int)

Encrypt the given block starting at the given offset and place the result in the provided buffer starting at the given offset.

engineDoFinal(byte[], int, int)

Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.

engineDoFinal(byte[], int, int, byte[], int)

Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.

engineGetBlockSize()

Returns the block size (in bytes).

engineGetIV()

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

engineGetOutputSize(int)

Returns the length in bytes that an output buffer would need to be in order to hold the result of the next update or doFinal operation, given the input length inputLen (in bytes).

engineGetParameters()

Returns the parameters used with this cipher.

engineInit(int, Key, AlgorithmParameters, SecureRandom)

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

engineInit(int, Key, AlgorithmParameterSpec, SecureRandom)

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

engineInit(int, Key, SecureRandom)

Initialises this cipher with a key and a source of randomness.

engineSetMode(String)

Sets the mode of this cipher.

engineSetPadding(String)

Sets the padding mechanism of this cipher.

engineUpdate(byte[], int, int)

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

engineUpdate(byte[], int, int, byte[], int)

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

reset()

Reset the Cipher to uninitialised.

setKey(Key)

Re-key the cipher.

 public static final String ident

 protected static final int BLOCK_SIZE

 protected static final int ECB

 protected static final int CBC

 protected byte buffer[]

 protected int bufferPos

 protected int mode

 protected boolean paddedStream

 protected int streamMode

 protected byte ivec[]

 protected byte cbcV[]

 protected boolean ivInline

 protected boolean ivEncrypted

 protected boolean firstBlock

 protected Key key

 protected SecureRandom random

 public BlockCipher()

 protected void engineSetMode(String mode) throws NoSuchAlgorithmException

Sets the mode of this cipher. Valid modes for are; ECB or CBC.

Parameters:

mode - the cipher mode

Throws: NoSuchAlgorithmException

if the requested cipher mode does not exist

Overrides:

engineSetMode in class CipherSpi

 protected void engineSetPadding(String padding) throws NoSuchPaddingException

Sets the padding mechanism of this cipher. Valid padding mechanisms are; "PKCS5Padding" and "NoPadding".

Parameters:

padding - the padding mechanism

Throws: NoSuchPaddingException

if the requested padding mechanism does not exist.

Overrides:

engineSetPadding in class CipherSpi

 protected int engineGetBlockSize()

Returns the block size (in bytes). In this case 8. This method should be overridden if the given algorithm has a different block size.

Returns:

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

Overrides:

engineGetBlockSize in class CipherSpi

 protected int engineGetOutputSize(int inputLen)

Returns the length in bytes that an output buffer would need to be in order to hold the result of the next update or doFinal operation, given the input length inputLen (in bytes).

This call takes into account any unprocessed (buffered) data from a previous update call, and padding.

The actual output length of the next update or doFinal call may be smaller than the length returned by this method.

Parameters:

inputLen - the input length (in bytes)

Returns:

the required output buffer size (in bytes)

Overrides:

engineGetOutputSize in class CipherSpi

 protected byte[] engineGetIV()

Returns the initialisation 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 initialisation 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.

Overrides:

engineGetIV in class CipherSpi

 protected AlgorithmParameters engineGetParameters()

Returns the parameters used with this cipher.

The returned parameters may be the same that were used to initialise this cipher, or may contain the default set of parameters or a set of randomly generated parameters used by the underlying cipher implementation (provided that the underlying cipher implementation uses a default set of parameters or creates new parameters if it needs parameters but was not initialised with any).

Returns:

the parameters used with this cipher, or null if this cipher does not use any parameters.

Overrides:

engineGetParameters in class CipherSpi

 protected void engineInit(int opmode,
                           Key key,
                           SecureRandom random) throws InvalidKeyException

Initialises this cipher with a key and a source of randomness.

The cipher is initialised for encryption or decryption, depending on the value of opmode.

If this cipher requires any algorithm parameters that cannot be derived from the given key, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialised for encryption, and raise an InvalidKeyException if it is being initialised for decryption. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV).

If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from random.

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

Parameters:

opmode - the operation mode of this cipher (this is either ENCRYPT_MODE or DECRYPT_MODE)

key - the encryption key

random - the source of randomness

Throws: InvalidKeyException

if the given key is inappropriate for initialising this cipher

Overrides:

engineInit in class CipherSpi

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

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

The cipher is initialised for 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 it is being initialised for encryption, and raise an InvalidAlgorithmParameterException if it is being initialised for decryption. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV).

If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from random.

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

Parameters:

opmode - the operation mode of this cipher (this is either ENCRYPT_MODE or DECRYPT_MODE)

key - the encryption key

params - the algorithm parameters

random - the source of randomness

Throws: InvalidKeyException

if the given key is inappropriate for initialising this cipher

Throws: InvalidAlgorithmParameterException

if the given algorithm parameters are inappropriate for this cipher, or if this cipher is being initialised fro decryption and requires algorithm parameters and params is null

Overrides:

engineInit in class CipherSpi

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

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

The cipher is initialised for 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 it is being initialised for encryption, and raise an InvalidAlgorithmParameterException if it is being initialised for decryption. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV).

If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from random.

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

Parameters:

opmode - the operation mode of this cipher (this is either ENCRYPT_MODE or DECRYPT_MODE)

key - the encryption key

params - the algorithm parameters

random - the source of randomness

Throws: InvalidKeyException

if the given key is inappropriate for initialising this cipher

Throws: InvalidAlgorithmParameterException

if the given algorithm parameters are inappropriate for this cipher, or if this cipher is being initialised fro decryption and requires algorithm parameters and params is null

Overrides:

engineInit in class CipherSpi

 protected byte[] engineUpdate(byte input[],
                               int inputOff,
                               int inputLen)

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

The first inputLen bytes in the input buffer, starting at inputOffset, 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.

Overrides:

engineUpdate in class CipherSpi

 protected int engineUpdate(byte input[],
                            int inputOff,
                            int inputLen,
                            byte output[],
                            int outputOff) throws ShortBufferException

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

The first inputLen bytes in the input buffer, starting at inputOffset, are processed, and the result is stored in the output buffer, starting at outputOffset.

If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.

Parameters:

input - the input buffer

inputOffset - the offset in input where the input starts

inputLen - the input length

output - the buffer for the result

outputOffset - the offset in output where the result is stored

Returns:

the number of bytes stored in output

Throws: ShortBufferException

if the given output buffer is too small to hold the result

Overrides:

engineUpdate in class CipherSpi

 protected byte[] engineDoFinal(byte input[],
                                int inputOff,
                                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 initialised.

The first inputLen bytes in the input buffer, starting at inputOffset, 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.

The cipher is reset to its initial state (uninitialised) after this call.

Parameters:

input - the input buffer

inputOff - 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

Throws: 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.

Overrides:

engineDoFinal in class CipherSpi

 protected int engineDoFinal(byte input[],
                             int inputOff,
                             int inputLen,
                             byte output[],
                             int outputOff) throws ShortBufferException, 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 initialised.

The first inputLen bytes in the input buffer, starting at inputOffset, 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 the output buffer, starting at outputOffset.

If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.

Parameters:

input - the input buffer

inputOffset - - the offset in input where the input starts

inputLen - - the input length

output - - the buffer for the result

outputOffset - - the offset in output where the result is stored

Returns:

s the number of bytes stored in output

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

Throws: ShortBufferException

if the given output buffer is too small to hold the result

Throws: 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

Overrides:

engineDoFinal in class CipherSpi

 protected void reset()

Reset the Cipher to uninitialised.

 protected abstract void setKey(Key key) throws InvalidKeyException

Re-key the cipher. If the provided Key is not compatible with this cipher the exception should throw an InvalidKeyException.

 protected abstract int encryptBlock(byte in[],
                                     int inoff,
                                     int len,
                                     byte out[],
                                     int outOff) throws IllegalBlockSizeException

Encrypt the given block starting at the given offset and place the result in the provided buffer starting at the given offset. The input will be an exact multiple of our blocksize.

 protected abstract int decryptBlock(byte in[],
                                     int inoff,
                                     int len,
                                     byte out[],
                                     int outOff) throws BadPaddingException

Decrypt the given block starting at the given offset and place the result in the provided buffer starting at the given offset. The input will be an exact multiple of our blocksize.

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