Cipher

public class Cipher extends Object

Known Direct Subclasses

NullCipher

This class provides the functionality of a cryptographic cipher for encryption and decryption. It forms the core of the Java Cryptographic Extension (JCE) framework.

In order to create a Cipher object, the application calls the Cipher's getInstance method, and passes the name of the requested transformation to it. Optionally, the name of a provider may be specified.

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");

Using modes such as CFB and OFB, block ciphers can encrypt data in units smaller than the cipher's actual block size. When requesting such a mode, you may optionally specify the number of bits to be processed at a time by appending this number to the mode name as shown in the "DES/CFB8/NoPadding" and "DES/OFB32/PKCS5Padding" transformations. If no such number is specified, a provider-specific default is used. (For example, the SunJCE provider uses a default of 64 bits for DES.) Thus, block ciphers can be turned into byte-oriented stream ciphers by using an 8 bit mode such as CFB8 or OFB8.

Modes such as Authenticated Encryption with Associated Data (AEAD) provide authenticity assurances for both confidential data and Additional Associated Data (AAD) that is not encrypted. (Please see RFC 5116 for more information on AEAD and AEAD algorithms such as GCM/CCM.) Both confidential and AAD data can be used when calculating the authentication tag (similar to a Mac). This tag is appended to the ciphertext during encryption, and is verified on decryption.

AEAD modes such as GCM/CCM perform all AAD authenticity calculations before starting the ciphertext authenticity calculations. To avoid implementations having to internally buffer ciphertext, all AAD data must be supplied to GCM/CCM implementations (via the updateAAD methods) before the ciphertext is processed (via the update and doFinal methods).

Note that GCM mode has a uniqueness requirement on IVs used in encryption with a given key. When IVs are repeated for GCM encryption, such usages are subject to forgery attacks. Thus, after each encryption operation using GCM mode, callers should re-initialize the cipher objects with GCM parameters which has a different IV value.

     GCMParameterSpec s = ...;
     cipher.init(..., s);

     // If the GCM parameters were generated by the provider, it can
     // be retrieved by:
     // cipher.getParameters().getParameterSpec(GCMParameterSpec.class);

     cipher.updateAAD(...);  // AAD
     cipher.update(...);     // Multi-part update
     cipher.doFinal(...);    // conclusion of operation

     // Use a different IV value for every encryption
     byte[] newIv = ...;
     s = new GCMParameterSpec(s.getTLen(), newIv);
     cipher.init(..., s);
     ...

Android provides the following Cipher transformations:

Algorithm	Modes	Paddings	Supported API Levels	Notes
AES	CBC CFB CTR CTS ECB OFB	ISO10126Padding NoPadding PKCS5Padding	1+
AES	GCM	NoPadding	10+
AES_128	CBC ECB	NoPadding PKCS5Padding	26+
AES_128	GCM	NoPadding	26+
AES_256	CBC ECB	NoPadding PKCS5Padding	26+
AES_256	GCM	NoPadding	26+
ARC4	ECB	NoPadding	10+
ARC4	NONE	NoPadding	28+
BLOWFISH	CBC CFB CTR CTS ECB OFB	ISO10126Padding NoPadding PKCS5Padding	10+
ChaCha20	NONE Poly1305	NoPadding	28+	ChaCha with 20 rounds, 96-bit nonce, and 32-bit counter as described in RFC 7539.
DES	CBC CFB CTR CTS ECB OFB	ISO10126Padding NoPadding PKCS5Padding	1+
DESede	CBC CFB CTR CTS ECB OFB	ISO10126Padding NoPadding PKCS5Padding	1+
RSA	ECB NONE	NoPadding OAEPPadding PKCS1Padding	1+
		OAEPwithSHA-1andMGF1Padding OAEPwithSHA-256andMGF1Padding	10+
		OAEPwithSHA-224andMGF1Padding OAEPwithSHA-384andMGF1Padding OAEPwithSHA-512andMGF1Padding	23+

These transformations are described in the Cipher section of the Java Cryptography Architecture Standard Algorithm Name Documentation.

Constant Summary

int	DECRYPT_MODE	Constant used to initialize cipher to decryption mode.
int	ENCRYPT_MODE	Constant used to initialize cipher to encryption mode.
int	PRIVATE_KEY	Constant used to indicate the to-be-unwrapped key is a "private key".
int	PUBLIC_KEY	Constant used to indicate the to-be-unwrapped key is a "public key".
int	SECRET_KEY	Constant used to indicate the to-be-unwrapped key is a "secret key".
int	UNWRAP_MODE	Constant used to initialize cipher to key-unwrapping mode.
int	WRAP_MODE	Constant used to initialize cipher to key-wrapping mode.

Protected Constructor Summary

Cipher(CipherSpi cipherSpi, Provider provider, String transformation)

Creates a Cipher object.

Public Method Summary

final 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.
final int	doFinal(byte[] output, int outputOffset) Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.
final byte[]	doFinal() Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.
final byte[]	doFinal(byte[] input) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
final 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.
final int	doFinal(ByteBuffer input, ByteBuffer output) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
final byte[]	doFinal(byte[] input, int inputOffset, int inputLen) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
final String	getAlgorithm() Returns the algorithm name of this `Cipher` object.
final int	getBlockSize() Returns the block size (in bytes).
final ExemptionMechanism	getExemptionMechanism() Returns the exemption mechanism object used with this cipher.
final byte[]	getIV() Returns the initialization vector (IV) in a new buffer.
final static Cipher	getInstance(String transformation) Returns a `Cipher` object that implements the specified transformation.
final static Cipher	getInstance(String transformation, String provider) Returns a `Cipher` object that implements the specified transformation.
final static Cipher	getInstance(String transformation, Provider provider) Returns a `Cipher` object that implements the specified transformation.
final static int	getMaxAllowedKeyLength(String transformation) Returns the maximum key length for the specified transformation according to the installed JCE jurisdiction policy files.
final static AlgorithmParameterSpec	getMaxAllowedParameterSpec(String transformation) Returns an AlgorithmParameterSpec object which contains the maximum cipher parameter value according to the jurisdiction policy file.
final 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).
final AlgorithmParameters	getParameters() Returns the parameters used with this cipher.
final Provider	getProvider() Returns the provider of this `Cipher` object.
final void	init(int opmode, Key key, AlgorithmParameters params) Initializes this cipher with a key and a set of algorithm parameters.
final void	init(int opmode, Certificate certificate, SecureRandom random) Initializes this cipher with the public key from the given certificate and a source of randomness.
final void	init(int opmode, Key key, SecureRandom random) Initializes this cipher with a key and a source of randomness.
final void	init(int opmode, Key key, AlgorithmParameterSpec params) Initializes this cipher with a key and a set of algorithm parameters.
final void	init(int opmode, Key key) Initializes this cipher with a key.
final 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.
final void	init(int opmode, Certificate certificate) Initializes this cipher with the public key from the given certificate.
final void	init(int opmode, Key key, AlgorithmParameters params, SecureRandom random) Initializes this cipher with a key, a set of algorithm parameters, and a source of randomness.
final Key	unwrap(byte[] wrappedKey, String wrappedKeyAlgorithm, int wrappedKeyType) Unwrap a previously wrapped key.
final byte[]	update(byte[] input) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
final 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.
final 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.
final int	update(ByteBuffer input, ByteBuffer output) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
final 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.
final void	updateAAD(byte[] src, int offset, int len) Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer.
final void	updateAAD(ByteBuffer src) Continues a multi-part update of the Additional Authentication Data (AAD).
final void	updateAAD(byte[] src) Continues a multi-part update of the Additional Authentication Data (AAD).
final byte[]	wrap(Key key) Wrap a key.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.

Constants

public static final int DECRYPT_MODE

Constant used to initialize cipher to decryption mode.

Constant Value: 2

public static final int ENCRYPT_MODE

Constant used to initialize cipher to encryption mode.

Constant Value: 1

public static final int PRIVATE_KEY

Constant used to indicate the to-be-unwrapped key is a "private key".

Constant Value: 2

public static final int PUBLIC_KEY

Constant used to indicate the to-be-unwrapped key is a "public key".

Constant Value: 1

public static final int SECRET_KEY

Constant used to indicate the to-be-unwrapped key is a "secret key".

Constant Value: 3

public static final int UNWRAP_MODE

Constant used to initialize cipher to key-unwrapping mode.

Constant Value: 4

public static final int WRAP_MODE

Constant used to initialize cipher to key-wrapping mode.

Constant Value: 3

Protected Constructors

protected Cipher (CipherSpi cipherSpi, Provider provider, String transformation)

Creates a Cipher object.

Parameters

cipherSpi	the delegate
provider	the provider
transformation	the transformation

Public Methods

public final 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. 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.

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.

Upon finishing, 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.

Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.

Note: this method should be copy-safe, which means the input and output buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

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; 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

public final int doFinal (byte[] output, int outputOffset)

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. 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.

Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.

Parameters

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; 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

public final byte[] doFinal ()

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

Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.

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; 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

public final byte[] doFinal (byte[] input)

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. 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.

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

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; 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

public final 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. The data is encrypted or decrypted, depending on how this cipher was initialized.

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

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; 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

public final int doFinal (ByteBuffer input, ByteBuffer output)

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 at input.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. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.

Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.

Parameters

input	the input ByteBuffer
output	the output ByteBuffer

Returns

the number of bytes stored in output

Throws

IllegalStateException	if this cipher is in a wrong state (e.g., has not been initialized)
IllegalArgumentException	if input and output are the same object
ReadOnlyBufferException	if the output buffer is read-only
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 there is insufficient space in the output buffer
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

public final byte[] doFinal (byte[] input, int inputOffset, int inputLen)

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.

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

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; 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

public final String getAlgorithm ()

Returns the algorithm name of this Cipher object.

This is the same name that was specified in one of the getInstance calls that created this Cipher object..

Returns

the algorithm name of this Cipher object.

public final int getBlockSize ()

Returns the block size (in bytes).

Returns

the block size (in bytes), or 0 if the underlying algorithm is not a block cipher

public final ExemptionMechanism getExemptionMechanism ()

Returns the exemption mechanism object used with this cipher.

Returns

the exemption mechanism object used with this cipher, or null if this cipher does not use any exemption mechanism.

public final byte[] getIV ()

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

This is useful in the case where a random IV was created, or in the context of password-based encryption or decryption, where the IV is derived from a user-supplied password.

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.

public static final Cipher getInstance (String transformation)

Returns a Cipher object that implements the specified transformation.

This method traverses the list of registered security Providers, starting with the most preferred Provider. A new Cipher object encapsulating the CipherSpi implementation from the first Provider that supports the specified algorithm is returned.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

Parameters

transformation	the name of the transformation, e.g., DES/CBC/PKCS5Padding. See the Cipher section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard transformation names.

Returns

a cipher that implements the requested transformation.

Throws

NoSuchAlgorithmException	if `transformation` is null, empty, in an invalid format, or if no Provider supports a CipherSpi implementation for the specified algorithm.
NoSuchPaddingException	if `transformation` contains a padding scheme that is not available.

public static final Cipher getInstance (String transformation, String provider)

Returns a Cipher object that implements the specified transformation.

A new Cipher object encapsulating the CipherSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

Parameters

transformation	the name of the transformation, e.g., DES/CBC/PKCS5Padding. See the Cipher section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard transformation names.
provider	the name of the provider.

Returns

a cipher that implements the requested transformation.

Throws

NoSuchAlgorithmException	if `transformation` is null, empty, in an invalid format, or if a CipherSpi implementation for the specified algorithm is not available from the specified provider.
NoSuchProviderException	if the specified provider is not registered in the security provider list.
NoSuchPaddingException	if `transformation` contains a padding scheme that is not available.
IllegalArgumentException	if the `provider` is null or empty.

public static final Cipher getInstance (String transformation, Provider provider)

Returns a Cipher object that implements the specified transformation.

A new Cipher object encapsulating the CipherSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.

Parameters

transformation	the name of the transformation, e.g., DES/CBC/PKCS5Padding. See the Cipher section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard transformation names.
provider	the provider.

Returns

a cipher that implements the requested transformation.

Throws

NoSuchAlgorithmException	if `transformation` is null, empty, in an invalid format, or if a CipherSpi implementation for the specified algorithm is not available from the specified Provider object.
NoSuchPaddingException	if `transformation` contains a padding scheme that is not available.
IllegalArgumentException	if the `provider` is null.

public static final int getMaxAllowedKeyLength (String transformation)

Returns the maximum key length for the specified transformation according to the installed JCE jurisdiction policy files. If JCE unlimited strength jurisdiction policy files are installed, Integer.MAX_VALUE will be returned. For more information on default key size in JCE jurisdiction policy files, please see Appendix E in the Java Cryptography Architecture Reference Guide.

Parameters

transformation	the cipher transformation.

Returns

the maximum key length in bits or Integer.MAX_VALUE.

Throws

NullPointerException	if `transformation` is null.
NoSuchAlgorithmException	if `transformation` is not a valid transformation, i.e. in the form of "algorithm" or "algorithm/mode/padding".

public static final AlgorithmParameterSpec getMaxAllowedParameterSpec (String transformation)

Returns an AlgorithmParameterSpec object which contains the maximum cipher parameter value according to the jurisdiction policy file. If JCE unlimited strength jurisdiction policy files are installed or there is no maximum limit on the parameters for the specified transformation in the policy file, null will be returned.

Parameters

transformation	the cipher transformation.

Returns

an AlgorithmParameterSpec which holds the maximum value or null.

Throws

NullPointerException	if `transformation` is null.
NoSuchAlgorithmException	if `transformation` is not a valid transformation, i.e. in the form of "algorithm" or "algorithm/mode/padding".

public final 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).

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)

Throws

IllegalStateException	if this cipher is in a wrong state (e.g., has not yet been initialized)

public final AlgorithmParameters getParameters ()

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.

public final Provider getProvider ()

Returns the provider of this Cipher object.

Returns

the provider of this Cipher object

public final void init (int opmode, Key key, AlgorithmParameters params)

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

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 getParameters or getIV (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 using the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.)

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

Throws

InvalidKeyException	if the given key is inappropriate for initializing this cipher, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files).
InvalidAlgorithmParameterException	if the given algorithm parameters are inappropriate for this cipher, or this cipher requires algorithm parameters and `params` is null, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits (as determined from the configured jurisdiction policy files).
UnsupportedOperationException	if (@code opmode} is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`.

public final void init (int opmode, Certificate certificate, SecureRandom random)

Initializes this cipher with the public key from the given certificate 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 the certificate is of type X.509 and has a key usage extension field marked as critical, and the value of the key usage extension field implies that the public key in the certificate and its corresponding private key are not supposed to be used for the operation represented by the value of opmode, an InvalidKeyException is thrown.

If this cipher requires any algorithm parameters that cannot be derived from the public key in the given certificate, 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 getParameters or getIV (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.

Parameters

opmode	the operation mode of this cipher (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
certificate	the certificate
random	the source of randomness

Throws

InvalidKeyException	if the public key in the given certificate is inappropriate for initializing this cipher, or this cipher requires algorithm parameters that cannot be determined from the public key in the given certificate, or the keysize of the public key in the given certificate has a keysize that exceeds the maximum allowable keysize (as determined by the configured jurisdiction policy files).
UnsupportedOperationException	if (@code opmode} is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`.

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

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 getParameters or getIV (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.

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, or if the given key has a keysize that exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files).
UnsupportedOperationException	if (@code opmode} is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`.

public final void init (int opmode, Key key, AlgorithmParameterSpec params)

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

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 algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

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

Throws

InvalidKeyException	if the given key is inappropriate for initializing this cipher, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files).
InvalidAlgorithmParameterException	if the given algorithm parameters are inappropriate for this cipher, or this cipher requires algorithm parameters and `params` is null, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits (as determined from the configured jurisdiction policy files).
UnsupportedOperationException	if (@code opmode} is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`.

public final void init (int opmode, Key key)

Initializes this cipher with a key.

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 algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

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 key

Throws

InvalidKeyException	if the given key is inappropriate for initializing this cipher, or requires algorithm parameters that cannot be determined from the given key, or if the given key has a keysize that exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files).
UnsupportedOperationException	if (@code opmode} is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`.

public final 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.

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 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.

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, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files).
InvalidAlgorithmParameterException	if the given algorithm parameters are inappropriate for this cipher, or this cipher requires algorithm parameters and `params` is null, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits (as determined from the configured jurisdiction policy files).
UnsupportedOperationException	if (@code opmode} is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`.

public final void init (int opmode, Certificate certificate)

Initializes this cipher with the public key from the given certificate.

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 public key in the given certificate, 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 getParameters or getIV (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.

Parameters

opmode	the operation mode of this cipher (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
certificate	the certificate

Throws

InvalidKeyException	if the public key in the given certificate is inappropriate for initializing this cipher, or this cipher requires algorithm parameters that cannot be determined from the public key in the given certificate, or the keysize of the public key in the given certificate has a keysize that exceeds the maximum allowable keysize (as determined by the configured jurisdiction policy files).
UnsupportedOperationException	if (@code opmode} is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`.

public final void init (int opmode, Key key, AlgorithmParameters params, SecureRandom random)

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 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.

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, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files).
InvalidAlgorithmParameterException	if the given algorithm parameters are inappropriate for this cipher, or this cipher requires algorithm parameters and `params` is null, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits (as determined from the configured jurisdiction policy files).
UnsupportedOperationException	if (@code opmode} is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`.

public final Key unwrap (byte[] wrappedKey, String wrappedKeyAlgorithm, int wrappedKeyType)

Unwrap a previously wrapped key.

Parameters

wrappedKey	the key to be unwrapped.
wrappedKeyAlgorithm	the algorithm associated with the wrapped key.
wrappedKeyType	the type of the wrapped key. This must be one of `SECRET_KEY`, `PRIVATE_KEY`, or `PUBLIC_KEY`.

Returns

the unwrapped key.

Throws

UnsupportedOperationException
IllegalStateException	if this cipher is in a wrong state (e.g., has not been initialized).
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`.

Cipher

See Also

Constant Summary

Protected Constructor Summary

Public Method Summary

Inherited Method Summary

Constants

public static final int DECRYPT_MODE

public static final int ENCRYPT_MODE

public static final int PRIVATE_KEY

public static final int PUBLIC_KEY

public static final int SECRET_KEY

public static final int UNWRAP_MODE

public static final int WRAP_MODE

Protected Constructors

protected Cipher (CipherSpi cipherSpi, Provider provider, String transformation)

Parameters

Public Methods

public final int doFinal (byte[] input, int inputOffset, int inputLen, byte[] output)

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public final int doFinal (byte[] output, int outputOffset)

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public final byte[] doFinal ()

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public final byte[] doFinal (byte[] input)

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public final int doFinal (byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset)

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public final int doFinal (ByteBuffer input, ByteBuffer output)

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public final byte[] doFinal (byte[] input, int inputOffset, int inputLen)

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public final String getAlgorithm ()

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public final int getBlockSize ()

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public final ExemptionMechanism getExemptionMechanism ()

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public final byte[] getIV ()

Returns

public static final Cipher getInstance (String transformation)

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Throws

See Also

public static final Cipher getInstance (String transformation, String provider)

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public static final Cipher getInstance (String transformation, Provider provider)

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See Also

public static final int getMaxAllowedKeyLength (String transformation)

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public static final AlgorithmParameterSpec getMaxAllowedParameterSpec (String transformation)

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public final int getOutputSize (int inputLen)

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Throws