Class javax.crypto.CipherSpi
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Class javax.crypto.CipherSpi

java.lang.Object
   |
   +----javax.crypto.CipherSpi

public class CipherSpi
extends Object
A parent class for the provider implementations of encryption/decryption objects.

Variable Index

 o ident

Constructor Index

 o CipherSpi()

Method Index

 o engineDoFinal(byte[], int, int)
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
 o engineDoFinal(byte[], int, int, byte[], int)
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
 o engineGetBlockSize()
Returns the block size (in bytes).
 o engineGetIV()
Returns the initialisation vector (IV) in a new buffer.
 o 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).
 o engineInit(int, Key, AlgorithmParameterSpec, SecureRandom)
Initialises this cipher with a key, a set of algorithm parameters, and a source of randomness.
 o engineInit(int, Key, SecureRandom)
Initialises this cipher with a key and a source of randomness.
 o engineSetMode(String)
Sets the mode of this cipher.
 o engineSetPadding(String)
Sets the padding mechanism of this cipher.
 o engineUpdate(byte[], int, int)
Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialised), processing another data part.
 o 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.

Variables

 o ident
  public final static String ident

Constructors

 o CipherSpi
  public CipherSpi()

Methods

 o engineSetMode
  protected abstract void engineSetMode(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
 o engineSetPadding
  protected abstract void engineSetPadding(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.
 o 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
 o engineGetOutputSize
  protected abstract 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)
 o engineGetIV
  protected abstract 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.
 o engineInit
  protected abstract 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 an initialisation vector (IV), it will get it from random. The random IV can be retrieved using getIV. This behaviour should only be used in encryption mode, however. When initialising a cipher that requires an IV for decryption, the IV (same IV that was used for encryption) must be provided explicitly as a parameter, in order to get the correct result.

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
 o engineInit
  protected abstract 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 (including its underlying feedback or padding scheme) requires any random bytes, 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
 o engineUpdate
  protected abstract byte[] engineUpdate(byte in[],
                                         int inOff,
                                         int inLen)
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.
 o engineUpdate
  protected abstract int engineUpdate(byte in[],
                                      int inOff,
                                      int inLen,
                                      byte out[],
                                      int outOff) 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
 o 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 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
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
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.
 o engineDoFinal
  protected abstract int engineDoFinal(byte in[],
                                       int inOff,
                                       int inLen,
                                       byte out[],
                                       int outOff) 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

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