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## javax.crypto
Class NullCipher

    java.lang.Object
      |
      +--javax.crypto.Cipher
            |
            +--javax.crypto.NullCipher

public class NullCipher
extends Cipher

The NullCipher class is a class that provides an "identity cipher" -- one that does not transform the plaintext. As a consequence, the ciphertext is identical to the plaintext. All initialization methods do nothing, while the blocksize is set to 1 byte.

Fields inherited from class javax.crypto.Cipher
`DECRYPT_MODE, ENCRYPT_MODE`

Constructor Summary
`NullCipher()`

Method Summary
`byte[]` | `doFinal()` Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.
`byte[]` | `doFinal(byte[] input)` Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`int` | `doFinal(byte[] output, int outputOffset)` Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.
`byte[]` | `doFinal(byte[] input, int inputOffset, int inputLen)` Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`int` | `doFinal(byte[] input, int inputOffset, int inputLen, byte[] output)` Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`int` | `doFinal(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset)` Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`int` | `getBlockSize()` Returns the block size (in bytes).
`byte[]` | `getIV()` Returns the initialization vector (IV) in a new buffer.
`int` | `getOutputSize(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).
`void` | `init(int opmode, Key key)` Initializes this cipher with a key.
`void` | `init(int opmode, Key key, AlgorithmParameterSpec params)` Initializes this cipher with a key and a set of algorithm parameters.
`void` | `init(int opmode, Key key, AlgorithmParameterSpec params, SecureRandom random)` Initializes this cipher with a key, a set of algorithm parameters, and a source of randomness.
`void` | `init(int opmode, Key key, SecureRandom random)` Initializes this cipher with a key and a source of randomness.
`byte[]` | `update(byte[] input)` Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
`byte[]` | `update(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.
`int` | `update(byte[] input, int inputOffset, int inputLen, byte[] output)` Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
`int` | `update(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset)` Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.

Methods inherited from class javax.crypto.Cipher
`getAlgorithm, getInstance, getInstance, getParameters, getProvider, init, init`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### NullCipher

    public NullCipher()

Method Detail

### init

    public void init(int opmode,
                     Key key)
              throws InvalidKeyException

  Description copied from class: Cipher

  Initializes this cipher with a key. The cipher is initialized for encryption or decryption, depending on the value of opmode.

  If this cipher requires an initialization vector (IV), it will get it from a system-provided source of randomness. The random IV can be retrieved using getIV. This behaviour should only be used in encryption mode, however. When initializing 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 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.

  Overrides:
    init in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `opmode` - the operation mode of this cipher (this is either ENCRYPT_MODE or DECRYPT_MODE)
    `key` - the key
  Throws:
    InvalidKeyException - if the given key is inappropriate for initializing this cipher

### init

    public void init(int opmode,
                     Key key,
                     SecureRandom random)
              throws InvalidKeyException

  Description copied from class: Cipher

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

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

  If this cipher requires an initialization 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 initializing 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 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.

  Overrides:
    init in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `opmode` - the operation mode of this cipher (this is either ENCRYPT_MODE or DECRYPT_MODE)
    `key` - the key
    `random` - the source of randomness
  Throws:
    InvalidKeyException - if the given key is inappropriate for initializing this cipher

### init

    public void init(int opmode,
                     Key key,
                     AlgorithmParameterSpec params)
              throws InvalidKeyException,
                     InvalidAlgorithmParameterException

  Description copied from class: Cipher

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

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

  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.

  Overrides:
    init in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `opmode` - the operation mode of this cipher (this is either ENCRYPT_MODE or DECRYPT_MODE)
    `key` - the key
    `params` - the algorithm parameters
  Throws:
    InvalidKeyException - if the given key is inappropriate for initializing this cipher
    InvalidAlgorithmParameterException - if the given algorithm parameters are inappropriate for this cipher

### init

    public void init(int opmode,
                     Key key,
                     AlgorithmParameterSpec params,
                     SecureRandom random)
              throws InvalidKeyException,
                     InvalidAlgorithmParameterException

  Description copied from class: Cipher

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

  The cipher is initialized 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 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.

  Overrides:
    init in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `opmode` - the operation mode of this cipher (this is either ENCRYPT_MODE or DECRYPT_MODE)
    `key` - the 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

### getBlockSize

    public int getBlockSize()

  Description copied from class: Cipher
  Returns the block size (in bytes).
  Overrides:
    getBlockSize in class Cipher
  Tags copied from class: Cipher
  Returns:
    the block size (in bytes)

### getOutputSize

    public int getOutputSize(int inputLen)
                      throws IllegalStateException

  Description copied from class: Cipher

  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.

  Overrides:
    getOutputSize in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `inputLen` - - the input length (in bytes)
  Returns:
    the required output buffer size (in bytes)
  Throws:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not yet been initialized)

### getIV

    public byte[] getIV()

  Description copied from class: Cipher

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

  This is useful in the case where a random IV has been created (see init), or in the context of password-based encryption or decryption, where the IV is derived from a user-provided passphrase.

  Overrides:
    getIV in class Cipher
  Tags copied from class: Cipher
  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.

### update

    public byte[] update(byte[] input)
                  throws IllegalStateException

  Description copied from class: Cipher

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

  The bytes in the input buffer are processed, and the result is stored in a new buffer.

  Overrides:
    update in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `input` - - the input buffer
  Returns:
    the new buffer with the result
  Throws:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)

### update

    public byte[] update(byte[] input,
                         int inputOffset,
                         int inputLen)
                  throws IllegalStateException

  Description copied from class: Cipher

  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, are processed, and the result is stored in a new buffer.

  Overrides:
    update in class Cipher
  Tags copied from class: Cipher
  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:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)

### update

    public int update(byte[] input,
                      int inputOffset,
                      int inputLen,
                      byte[] output)
               throws IllegalStateException,
                      ShortBufferException

  Description copied from class: Cipher

  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, are processed, and the result is stored in the output buffer.

  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.

  Overrides:
    update in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `input` - the input buffer
    `inputOffset` - the offset in input where the input starts
    `inputLen` - the input length
    `output` - the buffer for the result
  Returns:
    the number of bytes stored in output
  Throws:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)
    ShortBufferException - if the given output buffer is too small to hold the result

### update

    public int update(byte[] input,
                      int inputOffset,
                      int inputLen,
                      byte[] output,
                      int outputOffset)
               throws IllegalStateException,
                      ShortBufferException

  Description copied from class: Cipher

  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, 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.

  Overrides:
    update in class Cipher
  Tags copied from class: Cipher
  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:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)
    ShortBufferException - if the given output buffer is too small to hold the result

### doFinal

    public byte[] doFinal()
                   throws IllegalStateException,
                          IllegalBlockSizeException,
                          BadPaddingException

  Description copied from class: Cipher

  Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.

  Input data that may have been buffered during a previous update operation is 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 init. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to init) more data.

  Overrides:
    doFinal in class Cipher
  Tags copied from class: Cipher
  Returns:
    the new buffer with the result
  Throws:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)
    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

### doFinal

    public byte[] doFinal(byte[] input)
                   throws IllegalStateException,
                          IllegalBlockSizeException,
                          BadPaddingException

  Description copied from class: Cipher

  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 bytes in the input buffer, 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 init. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to init) more data.

  Overrides:
    doFinal in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `input` - the input buffer
  Returns:
    the new buffer with the result
  Throws:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)
    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

### doFinal

    public int doFinal(byte[] output,
                       int outputOffset)
                throws IllegalStateException,
                       IllegalBlockSizeException,
                       ShortBufferException,
                       BadPaddingException

  Description copied from class: Cipher

  Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.

  Input data that may have been buffered during a previous update operation is processed, with padding (if requested) being applied. The result is stored in a new buffer.

  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.

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

  Overrides:
    doFinal in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `input` - the input buffer
    `outputOffset` - the offset in output where the result is stored
  Returns:
    the new buffer with the result
  Throws:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)
    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
    ShortBufferException - if the given output buffer is too small to hold the result
    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

### doFinal

    public byte[] doFinal(byte[] input,
                          int inputOffset,
                          int inputLen)
                   throws IllegalStateException,
                          IllegalBlockSizeException,
                          BadPaddingException

  Description copied from class: Cipher

  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, 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 init. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to init) more data.

  Overrides:
    doFinal in class Cipher
  Tags copied from class: Cipher
  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:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)
    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

### doFinal

    public int doFinal(byte[] input,
                       int inputOffset,
                       int inputLen,
                       byte[] output)
                throws IllegalStateException,
                       ShortBufferException,
                       IllegalBlockSizeException,
                       BadPaddingException

  Description copied from class: Cipher

  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, 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.

  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.

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

  Overrides:
    doFinal in class Cipher
  Tags copied from class: Cipher
  Parameters:
    `input` - the input buffer
    `inputOffset` - the offset in input where the input starts
    `inputLen` - the input length
    `output` - the buffer for the result
  Returns:
    the number of bytes stored in output
  Throws:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)
    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
    ShortBufferException - if the given output buffer is too small to hold the result
    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

### doFinal

    public int doFinal(byte[] input,
                       int inputOffset,
                       int inputLen,
                       byte[] output,
                       int outputOffset)
                throws IllegalStateException,
                       ShortBufferException,
                       IllegalBlockSizeException,
                       BadPaddingException

  Description copied from class: Cipher

  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, 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.

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

  Overrides:
    doFinal in class Cipher
  Tags copied from class: Cipher
  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:
    IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)
    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
    ShortBufferException - if the given output buffer is too small to hold the result
    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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