javax.crypto
Class Cipher

java.lang.Object
  javax.crypto.Cipher

Direct Known Subclasses:

NullCipher

public class Cipher
extends Object

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");
 

When requesting a block cipher in stream cipher mode (e.g., DES in CFB or OFB mode), the user 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.)

See Also: KeyGenerator, SecretKey

Version:

$Id: Cipher.java 1913 2007-08-08 02:41:53Z jpeters $

Author:

Patric Kabus, Jan Peters

Field Summary

private CipherSpi	cipherSpi_ The cipher implementation used by this instance.
static int	DECRYPT_MODE Constant used to initialize cipher to decryption mode.
static int	ENCRYPT_MODE Constant used to initialize cipher to encryption mode.
private ExemptionMechanism	exemptionMechanism_ The exemption mechanism.
private boolean	init_ States wether this cipher has been initialised.
private int	opmode_ The opmode.
static int	PRIVATE_KEY Constant used to indicate the to-be-unwrapped key is a "private key".
private Provider	provider_ The provider used by this instance.
static int	PUBLIC_KEY Constant used to indicate the to-be-unwrapped key is a "public key".
static int	SECRET_KEY Constant used to indicate the to-be-unwrapped key is a "secret key".
private String	transformation_ The transformation used by this instance.
static int	UNWRAP_MODE Constant used to initialize cipher to key-unwrapping mode.
static int	WRAP_MODE Constant used to initialize cipher to key-wrapping mode.

Constructor Summary

protected

Cipher(CipherSpi cipherSpi, Provider provider, String transformation) Creates a Cipher object.

Method Summary

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

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

ENCRYPT_MODE

public static final int ENCRYPT_MODE

Constant used to initialize cipher to encryption mode.

See Also:

Constant Field Values

DECRYPT_MODE

public static final int DECRYPT_MODE

Constant used to initialize cipher to decryption mode.

See Also:

Constant Field Values

WRAP_MODE

public static final int WRAP_MODE

Constant used to initialize cipher to key-wrapping mode.

See Also:

Constant Field Values

UNWRAP_MODE

public static final int UNWRAP_MODE

Constant used to initialize cipher to key-unwrapping mode.

See Also:

Constant Field Values

PUBLIC_KEY

public static final int PUBLIC_KEY

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

See Also:

Constant Field Values

PRIVATE_KEY

public static final int PRIVATE_KEY

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

See Also:

Constant Field Values

SECRET_KEY

public static final int SECRET_KEY

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

See Also:

Constant Field Values

cipherSpi_

private CipherSpi cipherSpi_

The cipher implementation used by this instance.

provider_

private Provider provider_

The provider used by this instance.

init_

private boolean init_

States wether this cipher has been initialised.

transformation_

private String transformation_

The transformation used by this instance.

exemptionMechanism_

private ExemptionMechanism exemptionMechanism_

The exemption mechanism.

opmode_

private int opmode_

The opmode.

Constructor Detail

Cipher

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

Creates a Cipher object.

Parameters:

cipherSpi - The delegate.

provider - The provider.

transformation - The transformation.

Method Detail

getInstance

public static final Cipher getInstance(String transformation)
                                throws NoSuchAlgorithmException,
                                       NoSuchPaddingException

Generates a Cipher object that implements the specified transformation.

If the default provider package supplies an implementation of the requested transformation, an instance of Cipher containing that implementation is returned. If the transformation is not available in the default provider package, other provider packages are searched.

Parameters:

transformation - The name of the transformation, e.g., DES/CBC/PKCS5Padding. See Appendix A in the Java Cryptography Extension API Specification & Reference for information about standard transformation names.

Returns:

A cipher that implements the requested transformation

Throws:

NoSuchAlgorithmException - if the specified transformation is not available in the default provider package or any of the other provider packages that were searched.

NoSuchPaddingException - if transformation contains a padding scheme that is not available.

getInstance

public static final Cipher getInstance(String transformation,
                                       String provider)
                                throws NoSuchAlgorithmException,
                                       NoSuchProviderException,
                                       NoSuchPaddingException

Creates a Cipher object that implements the specified transformation, as supplied by the specified provider.

Parameters:

transformation - The name of the transformation, e.g., DES/CBC/PKCS5Padding. See Appendix A in the Java Cryptography Extension API Specification & Reference for information about standard transformation names.

provider - The name of the provider.

Returns:

A cipher that implements the requested transformation

Throws:

NoSuchAlgorithmException - if no transformation was specified, or if the specified transformation is not available from the specified provider.

NoSuchProviderException - if the specified provider has not been configured.

NoSuchPaddingException - if transformation contains a padding scheme that is not available.

IllegalArgumentException - if the provider is null.

getInstance

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

Creates a Cipher object that implements the specified transformation, as supplied by the specified provider. Note: the provider doesn't have to be registered.

Parameters:

transformation - The name of the transformation, e.g., DES/CBC/PKCS5Padding. See Appendix A in the Java Cryptography Extension API Specification & Reference for information about standard transformation names.

provider - the provider.

Returns:

a cipher that implements the requested transformation.

Throws:

NoSuchAlgorithmException - if no transformation was specified, or if the specified transformation is not available from the specified provider.

NoSuchPaddingException - if transformation contains a padding scheme that is not available.

IllegalArgumentException - if the provider is null.

initCipherSpi

private static CipherSpi initCipherSpi(CipherSpi cs,
                                       String transformation)
                                throws NoSuchAlgorithmException,
                                       NoSuchPaddingException

Initialize CipherSpi with for the given transformation.

Parameters:

cs - the CipherSpie to initialize.

transformation - the name of the transformation.

Returns:

the initialized CipherSpi

Throws:

NoSuchAlgorithmException

NoSuchPaddingException

getProvider

public final Provider getProvider()

Returns the provider of this Cipher object.

Returns:

The provider of this Cipher object.

getAlgorithm

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.

getBlockSize

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.

getOutputSize

public final int getOutputSize(int inputLen)
                        throws IllegalStateException

Returns the length in bytes that an output buffer would need to be in order to hold the result of the next update or doFinal operation, given the input length inputLen (in bytes).

This call takes into account any unprocessed (buffered) data from a previous update call, and padding.

The actual output length of the next update or doFinal call may be smaller than the length returned by this method.

Parameters:

inputLen - The input length (in bytes)

Returns:

The required output buffer size (in bytes)

Throws:

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

getIV

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.

getParameters

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.

getExemptionMechanism

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.

init

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

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 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 (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the java.security.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 key.

Throws:

InvalidKeyException - if the given key is inappropriate for initializing this cipher, or if this cipher is being initialized for decryption or key unwrapping and requires algorithm parameters that cannot be determined from the given key.

init

public final void init(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 inwrapping. The generated parameters can be retrieved using engineGetParameters() or engineGetIV() (if the parameter is an IV).

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 java.security.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 key.

random - The source of randomness.

Throws:

InvalidKeyException - - if the given key is inappropriate for initializing this cipher, or if this cipher is being initialized for decryption or key unwrapping and requires algorithm parameters that cannot be determined from the given key.

init

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

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 engineGetParameters() or engineGetIV() (if the parameter is an IV).

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 java.security.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

InvalidAlgorithmParameterException - if the given algorithm parameters are inappropriate for this cipher, or if this cipher is being initialized for decryption or key unwrapping and requires algorithm parameters and params is null.

init

public final void init(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, and raise an InvalidAlgorithmParameterException if it is being initialized for decryption. The generated parameters can be retrieved using engineGetParameters() or engineGetIV() (if the parameter is an IV).

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 java.security.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.

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 is being initialized for decryption or key unwrapping and requires algorithm parameters and params is null.

init

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

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 engineGetParameters() or engineGetIV() (if the parameter is an IV).

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 java.security.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.

InvalidAlgorithmParameterException - if the given algorithm parameters are inappropriate for this cipher, or if this cipher is being initialized for decryption or key unwrapping and requires algorithm parameters and params is null.

init

public final void init(int opmode,
                       Key key,
                       AlgorithmParameters 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 (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the java.security.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.

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 is being initialized for decryption or key unwrapping and requires algorithm parameters and params is null.

init

public final void init(int opmode,
                       Certificate certificate)
                throws InvalidKeyException

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 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 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 (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the java.security.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).

certificate - the certificate.

Throws:

InvalidKeyException - if the public key in the given certificate is inappropriate for initializing this cipher, or this cipher is being initialized for decryption or unwrapping keys and 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).

init

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

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 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 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 (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).

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 is being initialized for decryption or unwrapping keys and 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).

update

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

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

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

If input has a length of zero, this method returns null.

Parameters:

input - The input buffer.

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.

Throws:

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

IllegalArgumentException - if input is null.

update

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

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.

If inputLen is zero, this method returns null.

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.

Throws:

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

IllegalArgumentException - if input is null.

update

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

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.

If inputLen is zero, this method returns a length of zero.

Parameters:

input - The input buffer.

inputOffset - The offset in input where the input starts.

inputLen - The input length.

output - the buffer for the result.

Returns:

The number of bytes stored in output.

Throws:

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

ShortBufferException - if the given output buffer is too small to hold the result.

IllegalArgumentException - if input is null.

update

public final int update(byte[] input,
                        int inputOffset,
                        int inputLen,
                        byte[] output,
                        int outputOffset)
                 throws IllegalStateException,
                        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. In this case, repeat this call with a larger output buffer. Use getOutputSize() to determine how big the output buffer should be.

If inputLen is zero, this method returns a length of zero.

Parameters:

input - The input buffer.

inputOffset - The offset in input where the input starts.

inputLen - The input length.

output - The buffer for the result.

outputOffset - The offset in output where the result is stored.

Returns:

The number of bytes stored in output.

Throws:

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

ShortBufferException - if the given output buffer is too small to hold the result.

IllegalArgumentException - if input or outputis null.

update

public final int update(ByteBuffer input,
                        ByteBuffer output)
                 throws ShortBufferException

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

All input.remaining() bytes starting at input.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. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.

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

Parameters:

input - the input ByteBuffer

output - the output ByteByffer

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

ShortBufferException - if there is insufficient space in the output buffer

doFinal

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

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

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

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

Returns:

the number of bytes stored in output

Throws:

IllegalStateException - if this cipher is in a wrong state (e.g., has not been initializedor initialized for key wrapping/unwrapping).

IllegalBlockSizeException - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size.

BadPaddingException - if this cipher is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes

doFinal

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

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

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

If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize() to determine how big the output buffer should be.

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

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 or initialized for key wrapping/unwrapping).

IllegalBlockSizeException - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size.

ShortBufferException - if the given output buffer is too small to hold the result.

BadPaddingException - if this cipher is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes.

doFinal

public final byte[] doFinal(byte[] input)
                     throws IllegalStateException,
                            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 bytes in the input buffer, and any input bytes that may have been buffered during a previous update operation, are processed, with padding (if requested) being applied. The result is stored in a new buffer.

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

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 initializedor initialized for key wrapping/unwrapping).

IllegalBlockSizeException - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size.

BadPaddingException - if this cipher is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes.

doFinal

public final byte[] doFinal(byte[] input,
                            int inputOffset,
                            int inputLen)
                     throws IllegalStateException,
                            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. The result is stored in a new buffer.

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

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 initializedor initialized for key wrapping/unwrapping).

IllegalBlockSizeException - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size.

BadPaddingException - if this cipher is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes.

doFinal

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

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

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

If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize() to determine how big the output buffer should be.

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

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 initializedor initialized for key wrapping/unwrapping).

IllegalBlockSizeException - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size.

ShortBufferException - if the given output buffer is too small to hold the result.

BadPaddingException - if this cipher is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes.

doFinal

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

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

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

If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize() to determine how big the output buffer should be.

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

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 initializedor initialized for key wrapping/unwrapping).

IllegalBlockSizeException - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size.

ShortBufferException - if the given output buffer is too small to hold the result.

BadPaddingException - if this cipher is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes.

doFinal

public final int doFinal(ByteBuffer input,
                         ByteBuffer output)
                  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.

All input.remaining() bytes starting at input.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. 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 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 or initialized for key wrapping/unwrapping).

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

wrap

public final byte[] wrap(Key key)
                  throws IllegalStateException,
                         IllegalBlockSizeException,
                         InvalidKeyException

Wrap a key.

Parameters:

key - the key to be wrapped.

Returns:

the wrapped key.

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, 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).

unwrap

public final Key unwrap(byte[] wrappedKey,
                        String wrappedKeyAlgorithm,
                        int wrappedKeyType)
                 throws IllegalStateException,
                        InvalidKeyException,
                        NoSuchAlgorithmException

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:

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.

getMaxAllowedKeyLength

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 JCE 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".

getMaxAllowedParameterSpec

public static final AlgorithmParameterSpec getMaxAllowedParameterSpec(String transformation)
                                                               throws NoSuchAlgorithmException

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".

checkInputParameters

private void checkInputParameters(byte[] input,
                                  int inputOffset,
                                  int inputLen)

Check the input parameters for update and doFinal.

Parameters:

input - the input buffer.

inputOffset - the offset in input where the input starts.

inputLen - The input length (in bytes).

checkOutputParameters

private void checkOutputParameters(byte[] output,
                                   int outputOffset)

Check the output parameters for update and doFinal.

Parameters:

output - the output buffer.

outputOffset - the offset in output where the result is stored.

toString

public final String toString()

Returns the string representation of this class.

Overrides:

toString in class Object

Returns:

the string representation of this class.