xjava.security

Class Cipher

Implemented Interfaces:
Parameterized
Known Direct Subclasses:
Blowfish, CAST5, DES, DES2X, DESX, DES_EDE3, IDEA, LOKI91, Mode, RawElGamalCipher, RawRSACipher, RC2, RC4, Rijndael, SAFER, SPEED, Square

public abstract class Cipher
extends IJCE_Traceable
implements Parameterized

This class is used to provide the functionality of a general purpose encryption algorithm, such as DES or RSA. Encryption is used to ensure confidentiality of digital data.

This class follows the general algorithm architecture found elsewhere in the security API: the base class provides an algorithm-independent interface to basic encryption functionality, with provider implementation subclassing a subset of the behaviours.

Like other algorithm-based classes in Java Security, the Cipher class is separated between application and provider interfaces:

Cipher API
Cipher SPI
engineengineInitEncryptinitEncrypt

Ciphers represented by this class satisfy the following constraints:

Byte-oriented stream ciphers (or ciphers in CFB and OFB modes, for example) have plaintext and ciphertext block sizes of 1 byte. For public key ciphers, it is common for the block sizes to be dependent on the length of some parameter of the public key.

A block cipher implementation may either implement its own buffering (by passing implBuffering == true to the constructor), or leave it to the Cipher superclass (implBuffering == false). When the implementation handles buffering, data passed to update is passed directly on to engineUpdate, and data passed to crypt is passed to engineUpdate, followed immediately by a call to engineCrypt.

When the Cipher superclass handles buffering, up to one block is buffered, in order to ensure that the length of data passed to engineUpdate is always a multiple of the block size. In this case the engineCrypt method is not used.

Cipher implementations are not required or expected to be threadsafe. If methods of a single Cipher object are called simultaneously by more than one thread, the result will be unpredictable.

Copyright © 1997 Systemics Ltd on behalf of the Cryptix Development Team.
All rights reserved.

$Revision: 1.9 $

Authors:
David Hopwood
Raif S. Naffah
Since:
IJCE 1.0.0

Field Summary

static int
DECRYPT
The state of the cipher when it is ready to decrypt, that is, the state it is in right after a call to initDecrypt.
static int
ENCRYPT
The state of the cipher when it is ready to encrypt, that is, the state it is in right after a call to initEncrypt.
static int
UNINITIALIZED
The state of the cipher object when it is uninitialized, that is, the state it is in right after it has been created.

Fields inherited from class xjava.security.IJCE_Traceable

tracing

Constructor Summary

Cipher()
Deprecated.
Cipher(boolean implBuffering, String provider, String algorithm)
This constructor is identical to the previous one (with arguments boolean, boolean, String), except that it does not have the redundant implPadding parameter, and also allows the algorithm name to be specified.
Cipher(boolean implBuffering, boolean implPadding, String provider)
Constructor for a Cipher.

Method Summary

int
blockSize()
Returns the length of a block for this cipher.
Object
clone()
Returns a clone of this cipher.
byte[]
crypt(byte[] in)
Encrypts or decrypts the specified array of data, which will be automatically padded/unpadded as necessary.
byte[]
crypt(byte[] in, int offset, int length)
Encrypts or decrypts the specified array of data, which will be automatically padded/unpadded as necessary.
int
crypt(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
Encrypts or decrypts the specified subarray of data, pads or unpads it as necessary, and places the result in the specified output buffer.
byte[]
doFinal(byte[] in)
Equivalent to crypt(in).
byte[]
doFinal(byte[] in, int offset, int length)
Equivalent to crypt(in, offset, length).
int
doFinal(byte[] in, int inOffset, int inLen, byte[] out)
Equivalent to crypt(in, inOffset, inLen, out, 0).
int
doFinal(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
Equivalent to crypt(in, inOffset, inLen, out, outOffset).
protected int
engineBlockSize()
SPI: Returns the length of a block, in bytes.
protected int
engineCiphertextBlockSize()
SPI: Returns the length of a ciphertext block, in bytes.
protected int
engineCrypt(byte[] out, int outOffset)
SPI: Process data buffered by this cipher implementation.
protected Object
engineGetParameter(String param)
SPI: Gets the value of the specified algorithm parameter.
protected int
engineInBufferSize(int outLen, boolean isFinal)
SPI: Returns the minimum number of bytes of input, that will cause an output of outLen bytes from a call to engineUpdate (when isFinal is false), or successive calls to both engineUpdate and engineCrypt (when isFinal is true).
protected abstract void
engineInitDecrypt(Key key)
SPI: Initializes this cipher for decryption, using the specified key.
protected abstract void
engineInitEncrypt(Key key)
SPI: Initializes this cipher for encryption, using the specified key.
protected int
engineOutBufferSize(int inLen, boolean isFinal)
SPI: Returns the length of output buffer required for a given length of input, in bytes.
protected int
enginePlaintextBlockSize()
SPI: Returns the length of a plaintext block, in bytes.
protected void
engineSetPaddingScheme(PaddingScheme padding)
SPI: Sets the object that will implement padding for this cipher.
protected void
engineSetParameter(String param, Object value)
SPI: Sets the specified algorithm parameter to the specified value.
protected abstract int
engineUpdate(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
SPI: This is the main engine method for updating data.
String
getAlgorithm()
Returns this algorithm's standard cipher name (not including mode and padding).
static String[]
getAlgorithms()
Gets the standard names of all Ciphers implemented by any installed provider.
static String[]
getAlgorithms(Provider provider)
Gets the standard names of all Ciphers implemented by a provider.
int
getCiphertextBlockSize()
Returns the length of a ciphertext block, in bytes.
int
getInputBlockSize()
Returns the length of an input block, in bytes.
static Cipher
getInstance(String algorithm)
Generates a Cipher object that implements the given algorithm.
static Cipher
getInstance(String algorithm, String provider)
Generates a Cipher object that implements the given cipher, from the given provider.
static Cipher
getInstance(Cipher cipher, Mode mode, PaddingScheme padding)
Generates a new Cipher object by composing the given Cipher, Mode and PaddingScheme objects.
String
getMode()
Returns this algorithm's standard mode name.
int
getOutputBlockSize()
Returns the length of an output block, in bytes.
String
getPadding()
Returns this algorithm's standard padding scheme name.
protected PaddingScheme
getPaddingScheme()
Returns the object implementing padding for this cipher, or null if there is no such object.
Object
getParameter(String param)
Gets the value of the specified algorithm parameter.
int
getPlaintextBlockSize()
Returns the length of a plaintext block, in bytes.
String
getProvider()
Returns the name of the provider of this cipher.
int
getState()
Returns the state of this Cipher object.
int
inBufferSize(int outLen)
Returns the minimum number of bytes of input, that will cause an output of outLen bytes from a call to update (i.e.
int
inBufferSizeFinal(int outLen)
Returns the minimum number of bytes of input, that will cause an output of outLen bytes from a call to crypt (including padding for the final block of the stream, if applicable).
void
initDecrypt(Key key)
Initializes this cipher for decryption, using the specified key.
void
initEncrypt(Key key)
Initializes this cipher for encryption, using the specified key.
boolean
isPaddingBlockCipher()
Returns true if this cipher is a padding block cipher.
int
outBufferSize(int inLen)
Returns the size of the buffer necessary to hold the output resulting from a call to update (i.e.
int
outBufferSizeFinal(int inLen)
Returns the size of the buffer necessary to hold the output resulting from a call to crypt (including padding for the final block of the stream, if applicable).
void
setParameter(String param, Object value)
Sets the specified algorithm parameter to the specified value.
String
toString()
byte[]
update(byte[] in)
Encrypts or decrypts the specified array of data, which is not the final data in this stream.
byte[]
update(byte[] in, int offset, int length)
Encrypts or decrypts the specified subarray of data, which is not the final data in this stream.
int
update(byte[] in, int inOffset, int inLen, byte[] out)
Encrypts or decrypts the specified subarray of data, which is not the final data in this stream, and places the result in the specified output buffer (starting at offset 0).
int
update(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
Encrypts or decrypts the specified subarray of data, which is not the final data in this stream, and places the result in the specified output buffer.

Methods inherited from class xjava.security.IJCE_Traceable

disableTracing, enableTracing, traceMethod, traceResult, traceResult, traceVoidMethod

Field Details

DECRYPT

public static final int DECRYPT
The state of the cipher when it is ready to decrypt, that is, the state it is in right after a call to initDecrypt.
Field Value:
2

ENCRYPT

public static final int ENCRYPT
The state of the cipher when it is ready to encrypt, that is, the state it is in right after a call to initEncrypt.
Field Value:
1

UNINITIALIZED

public static final int UNINITIALIZED
The state of the cipher object when it is uninitialized, that is, the state it is in right after it has been created.
Field Value:
0

Constructor Details

Cipher

protected Cipher()

Deprecated.

The JCE docs say: "Constructor used for dynamic instantiation." I don't understand why this is needed. --DJH

Cipher

protected Cipher(boolean implBuffering,
                 String provider,
                 String algorithm)
Parameters:
implBuffering - if true, this argument indicates that data will always be passed from update/crypt to engineUpdate/engineCrypt without modification.
provider - the name of the provider of the underlying cryptographic engine.
algorithm - the name of this algorithm (optionally with mode and padding, separated by '/'), as it is configured in the properties file.

Cipher

protected Cipher(boolean implBuffering,
                 boolean implPadding,
                 String provider)
Parameters:
implBuffering - if true, this argument indicates that data will always be passed from update/crypt to engineUpdate/engineCrypt without modification.
implPadding - must be false.
provider - the name of the provider of the underlying cryptographic engine.

Method Details

blockSize

public final int blockSize()
Returns the length of a block for this cipher. If plaintext and ciphertext blocks are different lengths, this method throws an IllegalBlockSizeException.
Returns:
the length in bytes of a block.

clone

public Object clone()
            throws CloneNotSupportedException
Returns a clone of this cipher.

Note: In JavaSoft's version of JCE, Cipher.clone() is protected. This is not very useful, since then an application (as opposed to the cipher implementation itself) is not able to call it.


crypt

public final byte[] crypt(byte[] in)
            throws IllegalBlockSizeException
Encrypts or decrypts the specified array of data, which will be automatically padded/unpadded as necessary.

Whether the data is encrypted or decrypted depends on the cipher's initialization state. This method will automatically allocate an output buffer of the right size.

If the final block is incomplete, the cipher must have a padding scheme other than "NONE", and it must be in the ENCRYPT state. If this is not the case, an IllegalBlockSizeException will be thrown.

If the cipher is in the DECRYPT state and padding is being used, at least one full ciphertext block should be passed to crypt. This is necessary because the last block contains information needed to determine the length of the original plaintext.

Parameters:
in - the input data.
Returns:
the encryption or decryption result.
Throws:
IllegalBlockSizeException - if the final block cannot be padded or unpadded.

crypt

public final byte[] crypt(byte[] in,
                          int offset,
                          int length)
            throws IllegalBlockSizeException
Encrypts or decrypts the specified array of data, which will be automatically padded/unpadded as necessary.

Whether the data is encrypted or decrypted depends on the cipher's initialization state. This method will automatically allocate an output buffer of the right size.

If the final block is incomplete, the cipher must have a padding scheme other than "NONE", and it must be in the ENCRYPT state. If this is not the case, an IllegalBlockSizeException will be thrown.

If the cipher is in the DECRYPT state and padding is being used, at least one full ciphertext block should be passed to crypt. This is necessary because the last block contains information needed to determine the length of the original plaintext.

Parameters:
in - the input data.
offset - the offset indicating where the subarray starts in the in array.
length - the length of the subarray.
Returns:
the encryption or decryption result.
Throws:
IllegalBlockSizeException - if the final block cannot be padded or unpadded.

crypt

public final int crypt(byte[] in,
                       int inOffset,
                       int inLen,
                       byte[] out,
                       int outOffset)
            throws IllegalBlockSizeException
Encrypts or decrypts the specified subarray of data, pads or unpads it as necessary, and places the result in the specified output buffer.

Whether the data is encrypted or decrypted depends on the cipher's initialization state.

If the final block is incomplete, the cipher must have a padding scheme other than "NONE", and it must be in the ENCRYPT state. If this is not the case, an IllegalBlockSizeException will be thrown.

If the cipher is in the DECRYPT state and padding is being used, at least one full ciphertext block should be passed to crypt. This is necessary because the last block contains information needed to determine the length of the original plaintext.

Parameters:
in - the input data.
inOffset - the offset indicating where the subarray starts in the in array.
inLen - the length of the subarray.
out - the output buffer.
outOffset - the offset indicating where to start writing the result into the output buffer.
Returns:
the number of bytes written.

doFinal

public final byte[] doFinal(byte[] in)
            throws IllegalBlockSizeException
Equivalent to crypt(in).

This method is not supported in JavaSoft's version of JCE. However, an equivalent method is declared in the JCE 1.2 preview documentation for javax.crypto.Cipher.


doFinal

public final byte[] doFinal(byte[] in,
                            int offset,
                            int length)
            throws IllegalBlockSizeException
Equivalent to crypt(in, offset, length).

This method is not supported in JavaSoft's version of JCE. However, an equivalent method is declared in the JCE 1.2 preview documentation for javax.crypto.Cipher.


doFinal

public final int doFinal(byte[] in,
                         int inOffset,
                         int inLen,
                         byte[] out)
            throws IllegalBlockSizeException
Equivalent to crypt(in, inOffset, inLen, out, 0).

This method is not supported in JavaSoft's version of JCE. However, an equivalent method is declared in the JCE 1.2 preview documentation for javax.crypto.Cipher.


doFinal

public final int doFinal(byte[] in,
                         int inOffset,
                         int inLen,
                         byte[] out,
                         int outOffset)
            throws IllegalBlockSizeException
Equivalent to crypt(in, inOffset, inLen, out, outOffset).

This method is not supported in JavaSoft's version of JCE. However, an equivalent method is declared in the JCE 1.2 preview documentation for javax.crypto.Cipher.


engineBlockSize

protected int engineBlockSize()
SPI: Returns the length of a block, in bytes. Ciphers for which plaintext and ciphertext blocks are the same size may override this method. Otherwise, both enginePlaintextBlockSize and engineCiphertextBlockSize should be overridden.

The value may change when initEncrypt or initDecrypt is called, but it should not change at other times.

Returns:
the length in bytes of a block for this cipher.

engineCiphertextBlockSize

protected int engineCiphertextBlockSize()
SPI: Returns the length of a ciphertext block, in bytes. For byte-oriented stream ciphers, this method should return 1.

The value may change when initEncrypt or initDecrypt is called, but it should not change at other times.

The default implementation returns engineBlockSize().

Returns:
the length in bytes of a ciphertext block for this cipher.

engineCrypt

protected int engineCrypt(byte[] out,
                          int outOffset)
SPI: Process data buffered by this cipher implementation.

This method is overriden by ciphers that handle their own buffering (i.e. implBuffering == true). It should flush the internal buffer, and process any remaining data. By default, this method returns 0.

Ciphers that pass implBuffering == false to the superclass constructor need not override this method.

SECURITY: if array arguments are passed to native code, the implementation must ensure that a buffer overflow or illegal memory access cannot occur, regardless of the arguments passed to this method. I.e. the native library should not be called if:

   out == null || outOffset <320 ||
   (long)outOffset + (number of bytes to be written) > out.length
 

Note that the (long) cast is essential, because outOffset could be close to Integer.MAX_VALUE. The native method being called should be private. This is important because untrusted code could subclass the cipher implementation, and call this method directly with any arguments.

Parameters:
out - the output buffer into which to write the result.
Returns:
the number of bytes written.

engineGetParameter

protected Object engineGetParameter(String param)
            throws NoSuchParameterException,
                   InvalidParameterException
SPI: Gets the value of the specified algorithm parameter.

This method supplies a general-purpose mechanism through which it is possible to get the various parameters of this object. A parameter may be any settable parameter for the algorithm, such as block size, a source of random bits for IV generation (if appropriate), or an indication of whether or not to perform a specific but optional computation. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

The default implementation always throws a NoSuchParameterException.

This method is not supported in JavaSoft's version of JCE.

Parameters:
param - the string name of the parameter.
Returns:
the object that represents the parameter value.
Throws:
NoSuchParameterException - if there is no parameter with name param for this cipher implementation.

engineInBufferSize

protected int engineInBufferSize(int outLen,
                                 boolean isFinal)
SPI: Returns the minimum number of bytes of input, that will cause an output of outLen bytes from a call to engineUpdate (when isFinal is false), or successive calls to both engineUpdate and engineCrypt (when isFinal is true).

If implBuffering is false, this method need not take into account padding or buffered data when calculating the result. In this case outLen will be a multiple of the output block size (this may only be true for IJCE, not for other implementations of JCE).

The default implementation assumes that the output will have the same number of blocks as the input (i.e. the result is outLen / getOutputBlockSize() * getInputBlockSize()).

You will need to override this method if the cipher handles its own buffering.

Parameters:
outLen - the number of bytes of output
isFinal - whether the input includes the last block
Returns:
the length in bytes of the output block

engineInitDecrypt

protected abstract void engineInitDecrypt(Key key)
            throws KeyException
SPI: Initializes this cipher for decryption, using the specified key.

After a call to this method, the cipher's state is set to DECRYPT.

Parameters:
key - the key to use for decryption.

engineInitEncrypt

protected abstract void engineInitEncrypt(Key key)
            throws KeyException
SPI: Initializes this cipher for encryption, using the specified key.

After a call to this method, the cipher's state is set to ENCRYPT.

Parameters:
key - the key to use for encryption.

engineOutBufferSize

protected int engineOutBufferSize(int inLen,
                                  boolean isFinal)
SPI: Returns the length of output buffer required for a given length of input, in bytes. isFinal is true when this is the final block of input.

If implBuffering is false, the inLen parameter already takes into account the length of any required padding, and buffered data. In this case inLen will be a multiple of the input block size (this may only be true for IJCE, not for other implementations of JCE).

The default implementation assumes that the output will have the same number of blocks as the input (i.e. the result is inLen / getInputBlockSize() * getOutputBlockSize()).

You will need to override this method if the cipher handles its own buffering.

Parameters:
inLen - the number of bytes of input
isFinal - whether the last block is to be padded
Returns:
the length in bytes of the output block

enginePlaintextBlockSize

protected int enginePlaintextBlockSize()
SPI: Returns the length of a plaintext block, in bytes. For byte-oriented stream ciphers, this method should return 1.

The value may change when initEncrypt or initDecrypt is called, but it should not change at other times.

The default implementation returns engineBlockSize().

Returns:
the length in bytes of a plaintext block for this cipher.

engineSetPaddingScheme

protected void engineSetPaddingScheme(PaddingScheme padding)
SPI: Sets the object that will implement padding for this cipher.

Cipher implementations may override this method in order to be notified when the padding scheme is set (in this case they should always call super.engineSetPaddingScheme(padding)). Normally, overriding this method is not required.


engineSetParameter

protected void engineSetParameter(String param,
                                  Object value)
            throws NoSuchParameterException,
                   InvalidParameterException,
                   InvalidParameterTypeException
SPI: Sets the specified algorithm parameter to the specified value.

This method supplies a general-purpose mechanism through which it is possible to set the various parameters of this object. A parameter may be any settable parameter for the algorithm, such as block size, a source of random bits for IV generation (if appropriate), or an indication of whether or not to perform a specific but optional computation. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

The default implementation always throws a NoSuchParameterException.

This method is not supported in JavaSoft's version of JCE.

Parameters:
param - the string name of the parameter.
value - the parameter value.
Throws:
NoSuchParameterException - if there is no parameter with name param for this cipher implementation.
InvalidParameterTypeException - if value is the wrong type for this parameter.

engineUpdate

protected abstract int engineUpdate(byte[] in,
                                    int inOffset,
                                    int inLen,
                                    byte[] out,
                                    int outOffset)
SPI: This is the main engine method for updating data.

When implBuffering is true, this method will be called with the same data that is passed to update or crypt (i.e. there will be exactly one call to engineUpdate for each call to update or crypt).

When implBuffering is false, the Cipher superclass will ensure that when it calls this method, inLen is a non-negative multiple of getInputBlockSize().

in and out may be the same array, and the input and output regions may overlap. A cipher implementation should not use any part of in or out as working storage for intermediate steps of the algorithm. It should copy only the final result into the out array.

SECURITY: if array arguments are passed to native code, the implementation must ensure that a buffer overflow or illegal memory access cannot occur, regardless of the arguments passed to this method. I.e. the native library should not be called if:

   in == null || out == null || inLen <320 || inLen % (block size) != 0 ||
   inOffset <320 || (long)inOffset + inLen > in.length ||
   outOffset <320 || (long)outOffset + (number of bytes to be written) > out.length
 

Note that the (long) casts are essential, because inOffset or outOffset could be close to Integer.MAX_VALUE. The native method being called should be private. This is important because untrusted code could subclass the cipher implementation, and call this method directly with any arguments.

Parameters:
in - the input data.
inOffset - the offset into in specifying where the data starts.
inLen - the length of the subarray.
out - the output array.
outOffset - the offset indicating where to start writing into the out array.
Returns:
the number of bytes written.

getAlgorithm

public final String getAlgorithm()
Returns:
the standard cipher name (such as "DES").

getAlgorithms

public static String[] getAlgorithms()
Since:
IJCE 1.0.1

getAlgorithms

public static String[] getAlgorithms(Provider provider)
Since:
IJCE 1.0.1

getCiphertextBlockSize

public final int getCiphertextBlockSize()
Returns:
the length in bytes of a ciphertext block for this cipher.

getInputBlockSize

public final int getInputBlockSize()
Returns:
the length in bytes of an input block for this cipher.

getInstance

public static Cipher getInstance(String algorithm)
            throws NoSuchAlgorithmException
Generates a Cipher object that implements the given algorithm. If the default provider package contains a class implementing the algorithm, an instance of that class is returned. If it is not available in the default package, other packages are searched.

Any of the following formats can be used for the algorithm name:

See International JCE Standard Algorithm Names for a list of Cipher algorithm names.

Parameters:
algorithm - the algorithm name, as described above.
Returns:
the new Cipher object, in the UNINITIALIZED state.

getInstance

public static Cipher getInstance(String algorithm,
                                 String provider)
            throws NoSuchAlgorithmException,
                   NoSuchProviderException
Generates a Cipher object that implements the given cipher, from the given provider. The format of the cipher specification is as described for getInstance(String algorithm).

If the algorithm is implemented using more than one component (cipher, mode, and padding scheme), all of them must come from the given provider. More flexibility can be obtained by using the getInstance(Cipher, Mode, PaddingScheme) factory method. For example, to request "DES" from the SUN provider, "CBC" from the Cryptix provider, and "PKCS#5" from any provider, use:

    Cipher.getInstance(
        Cipher.getInstance("DES", "SUN"),
        Mode.getInstance("CBC", "Cryptix"),
        PaddingScheme.getInstance("PKCS#5")
    )
 

See International JCE Standard Algorithm Names for a list of Cipher algorithm names.

Parameters:
algorithm - the cipher specification.
Returns:
the new Cipher object, in the UNINITIALIZED state.

getInstance

public static Cipher getInstance(Cipher cipher,
                                 Mode mode,
                                 PaddingScheme padding)
Generates a new Cipher object by composing the given Cipher, Mode and PaddingScheme objects. mode may be null (indicating ECB), and padding may be null (indicating NONE).

This method is not supported in JavaSoft's version of JCE.


getMode

public final String getMode()
Returns:
the algorithm's standard mode name (such as "CBC")

getOutputBlockSize

public final int getOutputBlockSize()
Returns:
the length in bytes of an output block for this cipher.

getPadding

public final String getPadding()
Returns:
the algorithm's standard padding scheme name (such as "PKCS#7" or "NONE")

getPaddingScheme

protected final PaddingScheme getPaddingScheme()
Returns the object implementing padding for this cipher, or null if there is no such object.

getParameter

public Object getParameter(String param)
            throws NoSuchParameterException,
                   InvalidParameterException
Gets the value of the specified algorithm parameter.

This method supplies a general-purpose mechanism through which it is possible to get the various parameters of this object. A parameter may be any settable parameter for the algorithm, such as block size, a source of random bits for IV generation (if appropriate), or an indication of whether or not to perform a specific but optional computation. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

This method is not supported in JavaSoft's version of JCE.

Specified by:
getParameter in interface Parameterized
Parameters:
param - the string name of the parameter.
Returns:
the object that represents the parameter value.
Throws:
NoSuchParameterException - if there is no parameter with name param for this cipher implementation.

getPlaintextBlockSize

public final int getPlaintextBlockSize()
Returns:
the length in bytes of a plaintext block for this cipher.

getProvider

public final String getProvider()
Returns the name of the provider of this cipher.
Returns:
the provider name (such as "SUN" or "Cryptix")

getState

public final int getState()
Returns the state of this Cipher object. Possible states are:

Returns:
the state of this cipher object.

inBufferSize

public final int inBufferSize(int outLen)
Parameters:
outLen - the number of bytes of output required.

inBufferSizeFinal

public final int inBufferSizeFinal(int outLen)
Parameters:
outLen - the number of bytes of output required.

initDecrypt

public final void initDecrypt(Key key)
            throws KeyException
Initializes this cipher for decryption, using the specified key. A successful call to this method puts the cipher in the DECRYPT state. This method may be called on a cipher in any state. Any state information (key, feedback buffer, ...) is lost and reset.
Parameters:
key - the key to use for decryption.

initEncrypt

public final void initEncrypt(Key key)
            throws KeyException
Initializes this cipher for encryption, using the specified key. A successful call to this method puts the cipher in the ENCRYPT state. This method may be called on a cipher in any state. Any state information (key, feedback buffer, ...) is lost and reset.
Parameters:
key - the key to use for encryption.

isPaddingBlockCipher

public final boolean isPaddingBlockCipher()

outBufferSize

public final int outBufferSize(int inLen)
Returns the size of the buffer necessary to hold the output resulting from a call to update (i.e. not including padding). This call takes into account any incomplete block currently being buffered.
Parameters:
inLen - the number of bytes to process.

outBufferSizeFinal

public final int outBufferSizeFinal(int inLen)
Parameters:
inLen - the number of bytes to process.

setParameter

public void setParameter(String param,
                         Object value)
            throws NoSuchParameterException,
                   InvalidParameterException,
                   InvalidParameterTypeException
Sets the specified algorithm parameter to the specified value.

This method supplies a general-purpose mechanism through which it is possible to set the various parameters of this object. A parameter may be any settable parameter for the algorithm, such as block size, a source of random bits for IV generation (if appropriate), or an indication of whether or not to perform a specific but optional computation. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

This method is not supported in JavaSoft's version of JCE.

Specified by:
setParameter in interface Parameterized
Parameters:
param - the string identifier of the parameter.
value - the parameter value.
Throws:
NoSuchParameterException - if there is no parameter with name param for this cipher implementation.
InvalidParameterTypeException - if value is the wrong type for this parameter.

toString

public String toString()

update

public final byte[] update(byte[] in)
Parameters:
in - the input data.
Returns:
the encryption or decryption result.

update

public final byte[] update(byte[] in,
                           int offset,
                           int length)
Parameters:
in - the input data.
offset - the offset indicating where the subarray starts in the in array.
length - the length of the subarray.
Returns:
the encryption or decryption result.

update

public final int update(byte[] in,
                        int inOffset,
                        int inLen,
                        byte[] out)
Parameters:
in - the input data.
inOffset - the offset indicating where the subarray starts in the in array.
inLen - the length of the subarray.
out - the output buffer.
Returns:
the number of bytes written.

update

public final int update(byte[] in,
                        int inOffset,
                        int inLen,
                        byte[] out,
                        int outOffset)
Parameters:
in - the input data.
inOffset - the offset indicating where the subarray starts in the in array.
inLen - the length of the subarray.
out - the output buffer.
outOffset - the offset indicating where to start writing the result into the output buffer.
Returns:
the number of bytes written.