java.lang.Object
- javax.crypto.CipherSpi

```
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 algorithm.
In order to create an instance of Cipher, which encapsulates an instance of this CipherSpi class, an application calls one of the getInstance factory methods of the Cipher engine class and specifies the requested transformation. Optionally, the application may also specify the name of a provider.
A transformation is a string that describes the operation (or set of operations) to be performed on the given input, to produce some output. A transformation always includes the name of a cryptographic algorithm (e.g., DES), and may be followed by a feedback mode and padding scheme.
A transformation is of the form:
- "algorithm/mode/padding" or
- "algorithm"
(in the latter case, provider-specific default values for the mode and padding scheme are used). For example, the following is a valid transformation:
```
 Cipher c = Cipher.getInstance("DES/CBC/PKCS5Padding");
 
```
A provider may supply a separate class for each combination of algorithm/mode/padding, or may decide to provide more generic classes representing sub-transformations corresponding to algorithm or algorithm/mode or algorithm//padding (note the double slashes), in which case the requested mode and/or padding are set automatically by the getInstance methods of Cipher, which invoke the engineSetMode and engineSetPadding methods of the provider's subclass of CipherSpi.
A Cipher property in a provider master class may have one of the following formats:
- ```
     // provider's subclass of "CipherSpi" implements "algName" with
     // pluggable mode and padding
     Cipher.algName
 
```
- ```
     // provider's subclass of "CipherSpi" implements "algName" in the
     // specified "mode", with pluggable padding
     Cipher.algName/mode
 
```
- ```
     // provider's subclass of "CipherSpi" implements "algName" with the
     // specified "padding", with pluggable mode
     Cipher.algName//padding
 
```
- ```
     // provider's subclass of "CipherSpi" implements "algName" with the
     // specified "mode" and "padding"
     Cipher.algName/mode/padding
 
```
For example, a provider may supply a subclass of CipherSpi that implements DES/ECB/PKCS5Padding, one that implements DES/CBC/PKCS5Padding, one that implements DES/CFB/PKCS5Padding, and yet another one that implements DES/OFB/PKCS5Padding. That provider would have the following Cipher properties in its master class:
- ```
     Cipher.DES/ECB/PKCS5Padding
 
```
- ```
     Cipher.DES/CBC/PKCS5Padding
 
```
- ```
     Cipher.DES/CFB/PKCS5Padding
 
```
- ```
     Cipher.DES/OFB/PKCS5Padding
 
```
Another provider may implement a class for each of the above modes (i.e., one class for ECB, one for CBC, one for CFB, and one for OFB), one class for PKCS5Padding, and a generic DES class that subclasses from CipherSpi. That provider would have the following Cipher properties in its master class:
- ```
     Cipher.DES
 
```
The getInstance factory method of the Cipher engine class follows these rules in order to instantiate a provider's implementation of CipherSpi for a transformation of the form "algorithm":
1. Check if the provider has registered a subclass of CipherSpi for the specified "algorithm".
  If the answer is YES, instantiate this class, for whose mode and padding scheme default values (as supplied by the provider) are used.
  If the answer is NO, throw a NoSuchAlgorithmException exception.
The getInstance factory method of the Cipher engine class follows these rules in order to instantiate a provider's implementation of CipherSpi for a transformation of the form "algorithm/mode/padding":
1. Check if the provider has registered a subclass of CipherSpi for the specified "algorithm/mode/padding" transformation.
  If the answer is YES, instantiate it.
  If the answer is NO, go to the next step.
2. Check if the provider has registered a subclass of CipherSpi for the sub-transformation "algorithm/mode".
  If the answer is YES, instantiate it, and call engineSetPadding(padding) on the new instance.
  If the answer is NO, go to the next step.
3. Check if the provider has registered a subclass of CipherSpi for the sub-transformation "algorithm//padding" (note the double slashes).
  If the answer is YES, instantiate it, and call engineSetMode(mode) on the new instance.
  If the answer is NO, go to the next step.
4. Check if the provider has registered a subclass of CipherSpi for the sub-transformation "algorithm".
  If the answer is YES, instantiate it, and call engineSetMode(mode) and engineSetPadding(padding) on the new instance.
  If the answer is NO, throw a NoSuchAlgorithmException exception.
Since:

1.4

See Also:

KeyGenerator, SecretKey

Constructor Summary

Constructors
Constructor Description

CipherSpi()

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`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`	`engineDoFinal(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.
`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 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).
`protected abstract void`	`engineInit(int opmode, Key key, SecureRandom random)`	Initializes this cipher with a key and a source of randomness.
`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 Key`	`engineUnwrap(byte[] wrappedKey, java.lang.String wrappedKeyAlgorithm, int wrappedKeyType)`	Unwrap a previously wrapped key.
`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.
`protected abstract int`	`engineUpdate(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.
`protected void`	`engineUpdateAAD(byte[] src, int offset, int len)`	Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer.
`protected byte[]`	`engineWrap(Key key)`	Wrap a key.

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
  - 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
  - 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, padding, and AEAD tagging.
    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)
  - 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,
                                   SecureRandom random)
                            throws InvalidKeyException
```
    Initializes this cipher with a key and a source of randomness.
    The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, 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 initialized for encryption or key wrapping, and raise an InvalidKeyException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV).
    If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.
    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 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, WRAP_MODE or UNWRAP_MODE)
    
    key - the encryption key
    
    random - the source of randomness
    
    Throws:
    
    InvalidKeyException - if the given key is inappropriate for initializing this cipher, or requires algorithm parameters that cannot be determined from the given key.
    
    java.lang.UnsupportedOperationException - if opmode is WRAP_MODE or UNWRAP_MODE is not implemented by the cipher.
  - 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 four operations: encryption, decryption, key wrapping or key unwrapping, 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 initialized for encryption or key wrapping, and raise an InvalidAlgorithmParameterException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV).
    If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.
    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 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, WRAP_MODE or UNWRAP_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 requires algorithm parameters and params is null.
    
    java.lang.UnsupportedOperationException - if opmode is WRAP_MODE or UNWRAP_MODE is not implemented by the cipher.
  - 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.
  - engineUpdate
```
protected abstract int engineUpdate(byte[] input,
                                    int inputOffset,
                                    int inputLen,
                                    byte[] output,
                                    int outputOffset)
                             throws ShortBufferException
```
    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 the output buffer, starting at outputOffset inclusive.
    If the output buffer is too small to hold the result, a ShortBufferException is thrown.
    
    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
  - 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. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in a new buffer.
    Upon finishing, 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.
    Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.
    
    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; or if this encryption algorithm is unable to process the input data provided.
    
    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
    
    AEADBadTagException - if this cipher is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value
  - engineDoFinal
```
protected abstract int engineDoFinal(byte[] input,
                                     int inputOffset,
                                     int inputLen,
                                     byte[] output,
                                     int outputOffset)
                              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 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. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the output buffer, starting at outputOffset inclusive.
    If the output buffer is too small to hold the result, a ShortBufferException is thrown.
    Upon finishing, 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.
    Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.
    
    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:
    
    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; or if this encryption algorithm is unable to process the input data provided.
    
    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
    
    AEADBadTagException - if this cipher is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value
  - engineWrap
```
protected byte[] engineWrap(Key key)
                     throws IllegalBlockSizeException,
                            InvalidKeyException
```
    Wrap a key.
    This concrete method has been added to this previously-defined abstract class. (For backwards compatibility, it cannot be abstract.) It may be overridden by a provider to wrap a key. Such an override is expected to throw an IllegalBlockSizeException or InvalidKeyException (under the specified circumstances), if the given key cannot be wrapped. If this method is not overridden, it always throws an UnsupportedOperationException.
    
    Parameters:
    
    key - the key to be wrapped.
    
    Returns:
    
    the wrapped key.
    
    Throws:
    
    IllegalBlockSizeException - if this cipher is a block cipher, no padding has been requested, and the length of the encoding of the key to be wrapped is not a multiple of the block size.
    
    InvalidKeyException - if it is impossible or unsafe to wrap the key with this cipher (e.g., a hardware protected key is being passed to a software-only cipher).
    
    java.lang.UnsupportedOperationException - if this method is not supported.
  - engineUnwrap
```
protected Key engineUnwrap(byte[] wrappedKey,
                           java.lang.String wrappedKeyAlgorithm,
                           int wrappedKeyType)
                    throws InvalidKeyException,
                           NoSuchAlgorithmException
```
    Unwrap a previously wrapped key.
    This concrete method has been added to this previously-defined abstract class. (For backwards compatibility, it cannot be abstract.) It may be overridden by a provider to unwrap a previously wrapped key. Such an override is expected to throw an InvalidKeyException if the given wrapped key cannot be unwrapped. If this method is not overridden, it always throws an UnsupportedOperationException.
    
    Parameters:
    
    wrappedKey - the key to be unwrapped.
    
    wrappedKeyAlgorithm - the algorithm associated with the wrapped key.
    
    wrappedKeyType - the type of the wrapped key. This is one of SECRET_KEY, PRIVATE_KEY, or PUBLIC_KEY.
    
    Returns:
    
    the unwrapped key.
    
    Throws:
    
    NoSuchAlgorithmException - if no installed providers can create keys of type wrappedKeyType for the wrappedKeyAlgorithm.
    
    InvalidKeyException - if wrappedKey does not represent a wrapped key of type wrappedKeyType for the wrappedKeyAlgorithm.
    
    java.lang.UnsupportedOperationException - if this method is not supported.
  - engineUpdateAAD
```
protected void engineUpdateAAD(byte[] src,
                               int offset,
                               int len)
```
    Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer.
    Calls to this method provide AAD to the cipher when operating in modes such as AEAD (GCM/CCM). If this cipher is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the update and doFinal methods).
    
    Parameters:
    
    src - the buffer containing the AAD
    
    offset - the offset in src where the AAD input starts
    
    len - the number of AAD bytes
    
    Throws:
    
    java.lang.IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized), does not accept AAD, or if operating in either GCM or CCM mode and one of the update methods has already been called for the active encryption/decryption operation
    
    java.lang.UnsupportedOperationException - if this method has not been overridden by an implementation
    
    Since:
    
    1.7

Class CipherSpi

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

CipherSpi

Method Detail

engineGetBlockSize

engineGetOutputSize

engineGetIV

engineInit

engineInit

engineUpdate

engineUpdate

engineDoFinal

engineDoFinal

engineWrap

engineUnwrap

engineUpdateAAD