CipherSpi (Java SE 15 & JDK 15) (original) (raw)

public abstract class CipherSpi extends 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 thegetInstance factory methods of theCipher 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., AES), 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("_AES/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 andengineSetPadding 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 AES/ECB/PKCS5Padding, one that implements_AES/CBC/PKCS5Padding_, one that implements_AES/CFB/PKCS5Padding_, and yet another one that implements_AES/OFB/PKCS5Padding_. That provider would have the followingCipher properties in its master class:

• Cipher.AES/ECB/PKCS5Padding
• Cipher.AES/CBC/PKCS5Padding
• Cipher.AES/CFB/PKCS5Padding
• Cipher.AES/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 AES class that subclasses from CipherSpi. That provider would have the followingCipher properties in its master class:

• Cipher.AES

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 callengineSetPadding(_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 callengineSetMode(_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 callengineSetMode(_mode_) andengineSetPadding(_padding_) on the new instance.
   If the answer is NO, throw a NoSuchAlgorithmException exception.

Since:

1.4

See Also:

KeyGenerator, SecretKey

• Constructor Summary

Constructors

• Method Summary

Methods declared in class java.lang.Object

[clone](../../java/lang/Object.html#clone%28%29), [equals](../../java/lang/Object.html#equals%28java.lang.Object%29), [finalize](../../java/lang/Object.html#finalize%28%29), [getClass](../../java/lang/Object.html#getClass%28%29), [hashCode](../../java/lang/Object.html#hashCode%28%29), [notify](../../java/lang/Object.html#notify%28%29), [notifyAll](../../java/lang/Object.html#notifyAll%28%29), [toString](../../java/lang/Object.html#toString%28%29), [wait](../../java/lang/Object.html#wait%28%29), [wait](../../java/lang/Object.html#wait%28long%29), [wait](../../java/lang/Object.html#wait%28long,int%29)

• Constructor Details

  • CipherSpi

  public CipherSpi()

• Method Details

  • engineSetMode

  Sets the mode of this cipher.
  Parameters:
  mode - the cipher mode
  Throws:
  [NoSuchAlgorithmException](../../java/security/NoSuchAlgorithmException.html "class in java.security") - if the requested cipher mode does not exist

  • engineSetPadding

  Sets the padding mechanism of this cipher.
  Parameters:
  padding - the padding mechanism
  Throws:
  [NoSuchPaddingException](NoSuchPaddingException.html "class in javax.crypto") - if the requested padding mechanism does not exist

  • 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 lengthinputLen (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 ordoFinal 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.

  • engineGetParameters

  Returns the parameters used with this cipher.
  The returned parameters may be the same that were used to initialize this cipher, or may contain a combination of default and random parameter values used by the underlying cipher implementation if this cipher requires algorithm parameters but was not initialized with any.
  Returns:
  the parameters used with this cipher, or null if this cipher does not use any parameters.

  • engineInit

  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 anInvalidKeyException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved usingengineGetParameters orengineGetIV (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](../../java/security/InvalidKeyException.html "class in java.security") - if the given key is inappropriate for initializing this cipher, or requires algorithm parameters that cannot be determined from the given key.
  [UnsupportedOperationException](../../java/lang/UnsupportedOperationException.html "class in java.lang") - if opmode isWRAP_MODE or UNWRAP_MODE is not implemented by the cipher.

  • engineInit

  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 andparams 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 anInvalidAlgorithmParameterException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved usingengineGetParameters orengineGetIV (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](../../java/security/InvalidKeyException.html "class in java.security") - if the given key is inappropriate for initializing this cipher
  [InvalidAlgorithmParameterException](../../java/security/InvalidAlgorithmParameterException.html "class in java.security") - if the given algorithm parameters are inappropriate for this cipher, or if this cipher requires algorithm parameters and params is null.
  [UnsupportedOperationException](../../java/lang/UnsupportedOperationException.html "class in java.lang") - if opmode isWRAP_MODE or UNWRAP_MODE is not implemented by the cipher.

  • engineInit

  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 andparams 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 anInvalidAlgorithmParameterException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved usingengineGetParameters orengineGetIV (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](../../java/security/InvalidKeyException.html "class in java.security") - if the given key is inappropriate for initializing this cipher
  [InvalidAlgorithmParameterException](../../java/security/InvalidAlgorithmParameterException.html "class in java.security") - if the given algorithm parameters are inappropriate for this cipher, or if this cipher requires algorithm parameters and params is null.
  [UnsupportedOperationException](../../java/lang/UnsupportedOperationException.html "class in java.lang") - if opmode isWRAP_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 atoutputOffset 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](ShortBufferException.html "class in javax.crypto") - if the given output buffer is too small to hold the result

  • engineUpdate

  Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
  All input.remaining() bytes starting atinput.position() are processed. The result is stored in the output buffer. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. The output buffer's position will have advanced by n, where n is the value returned by this method; the output buffer's limit will not have changed.
  If output.remaining() bytes are insufficient to hold the result, a ShortBufferException is thrown.
  Subclasses should consider overriding this method if they can process ByteBuffers more efficiently than byte arrays.
  Parameters:
  input - the input ByteBuffer
  output - the output ByteByffer
  Returns:
  the number of bytes stored in output
  Throws:
  [ShortBufferException](ShortBufferException.html "class in javax.crypto") - if there is insufficient space in the output buffer
  [NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if either parameter is null
  Since:
  1.5

  • engineDoFinal

  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 toengineInit. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call toengineInit) 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](IllegalBlockSizeException.html "class in javax.crypto") - 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](BadPaddingException.html "class in javax.crypto") - 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](AEADBadTagException.html "class in javax.crypto") - 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

  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 atoutputOffset 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 toengineInit. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call toengineInit) 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](IllegalBlockSizeException.html "class in javax.crypto") - 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](ShortBufferException.html "class in javax.crypto") - if the given output buffer is too small to hold the result
  [BadPaddingException](BadPaddingException.html "class in javax.crypto") - 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](AEADBadTagException.html "class in javax.crypto") - 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

  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.
  All input.remaining() bytes starting atinput.position() are processed. 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. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. The output buffer's position will have advanced by n, where n is the value returned by this method; the output buffer's limit will not have changed.
  If output.remaining() bytes are insufficient 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 toengineInit. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call toengineInit) more data.
  Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.
  Subclasses should consider overriding this method if they can process ByteBuffers more efficiently than byte arrays.
  Parameters:
  input - the input ByteBuffer
  output - the output ByteByffer
  Returns:
  the number of bytes stored in output
  Throws:
  [IllegalBlockSizeException](IllegalBlockSizeException.html "class in javax.crypto") - 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](ShortBufferException.html "class in javax.crypto") - if there is insufficient space in the output buffer
  [BadPaddingException](BadPaddingException.html "class in javax.crypto") - 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](AEADBadTagException.html "class in javax.crypto") - if this cipher is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value
  [NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if either parameter is null
  Since:
  1.5

  • engineWrap

  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](IllegalBlockSizeException.html "class in javax.crypto") - 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](../../java/security/InvalidKeyException.html "class in java.security") - 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).
  [UnsupportedOperationException](../../java/lang/UnsupportedOperationException.html "class in java.lang") - if this method is not supported.

  • engineUnwrap

  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 ofSECRET_KEY, PRIVATE_KEY, orPUBLIC_KEY.
  Returns:
  the unwrapped key.
  Throws:
  [NoSuchAlgorithmException](../../java/security/NoSuchAlgorithmException.html "class in java.security") - if no installed providers can create keys of type wrappedKeyType for thewrappedKeyAlgorithm.
  [InvalidKeyException](../../java/security/InvalidKeyException.html "class in java.security") - if wrappedKey does not represent a wrapped key of type wrappedKeyType for the wrappedKeyAlgorithm.
  [UnsupportedOperationException](../../java/lang/UnsupportedOperationException.html "class in java.lang") - if this method is not supported.

  • engineGetKeySize

  Returns the key size of the given key object in bits.
  This concrete method has been added to this previously-defined abstract class. It throws an UnsupportedOperationException if it is not overridden by the provider.
  Parameters:
  key - the key object.
  Returns:
  the key size of the given key object.
  Throws:
  [InvalidKeyException](../../java/security/InvalidKeyException.html "class in java.security") - if key is invalid.

  • 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:
  [IllegalStateException](../../java/lang/IllegalStateException.html "class in java.lang") - 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
  [UnsupportedOperationException](../../java/lang/UnsupportedOperationException.html "class in java.lang") - if this method has not been overridden by an implementation
  Since:
  1.7

  • engineUpdateAAD

  protected void engineUpdateAAD​(ByteBuffer src)
  Continues a multi-part update of the Additional Authentication Data (AAD).
  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).
  All src.remaining() bytes starting atsrc.position() are processed. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed.
  Parameters:
  src - the buffer containing the AAD
  Throws:
  [IllegalStateException](../../java/lang/IllegalStateException.html "class in java.lang") - 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
  [UnsupportedOperationException](../../java/lang/UnsupportedOperationException.html "class in java.lang") - if this method has not been overridden by an implementation
  Since:
  1.7