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java.lang.Object | +--javax.crypto.Cipher
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:
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.)
KeyGenerator
,
SecretKey
Field Summary | |
static int |
DECRYPT_MODE
|
static int |
ENCRYPT_MODE
|
static java.lang.String |
ident
|
Constructor Summary | |
protected |
Cipher(CipherSpi cipherSpi,
java.security.Provider provider,
java.lang.String transformation)
Creates a Cipher object. |
Method Summary | |
byte[] |
doFinal()
Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialised. |
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 initialised. |
byte[] |
doFinal(byte[] input,
int inputOffset,
int inputLen)
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. |
int |
doFinal(byte[] input,
int inputOffset,
int inputLen,
byte[] output)
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. |
int |
doFinal(byte[] input,
int inputOffset,
int inputLen,
byte[] output,
int outputOffset)
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. |
java.lang.String |
getAlgorithm()
Returns the algorithm name of this Cipher object. |
int |
getBlockSize()
Returns the block size (in bytes). |
static Cipher |
getInstance(java.lang.String transformation)
Generates a Cipher object that implements the specified transformation. |
static Cipher |
getInstance(java.lang.String transformation,
java.lang.String provider)
Creates a Cipher object that implements the specified transformation, as supplied by the specified provider. |
byte[] |
getIV()
Returns the initialisation vector (IV) in a new buffer. |
int |
getOutputSize(int inputLen)
Returns the length in bytes that an output buffer would need to be in order to hold the result of the next update or doFinal operation, given the input length inputLen (in bytes). |
java.security.AlgorithmParameters |
getParameters()
Returns the parameters used with this cipher. |
java.security.Provider |
getProvider()
Returns the provider of this Cipher object. |
void |
init(int opmode,
java.security.Key key)
Initialises this cipher with a key. |
void |
init(int opmode,
java.security.Key key,
java.security.AlgorithmParameters params)
Initialises this cipher with a key and a set of algorithm parameters. |
void |
init(int opmode,
java.security.Key key,
java.security.spec.AlgorithmParameterSpec params)
Initialises this cipher with a key and a set of algorithm parameters. |
void |
init(int opmode,
java.security.Key key,
java.security.spec.AlgorithmParameterSpec params,
java.security.SecureRandom random)
Initialises this cipher with a key, a set of algorithm parameters, and a source of randomness. |
void |
init(int opmode,
java.security.Key key,
java.security.AlgorithmParameters params,
java.security.SecureRandom random)
Initialises this cipher with a key, a set of algorithm parameters, and a source of randomness. |
void |
init(int opmode,
java.security.Key key,
java.security.SecureRandom random)
Initialises this cipher with a key and a source of randomness. |
byte[] |
update(byte[] input)
Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialised), 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 initialised), 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 initialised), 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 initialised), processing another data part. |
Methods inherited from class java.lang.Object |
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait |
Field Detail |
public static final java.lang.String ident
public static final int ENCRYPT_MODE
public static final int DECRYPT_MODE
Constructor Detail |
protected Cipher(CipherSpi cipherSpi, java.security.Provider provider, java.lang.String transformation)
cipherSpi
- the delegateprovider
- the providertransformation
- the transformationMethod Detail |
public static final Cipher getInstance(java.lang.String transformation) throws java.security.NoSuchAlgorithmException, NoSuchPaddingException
If the default provider package provides 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.
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.public static final Cipher getInstance(java.lang.String transformation, java.lang.String provider) throws java.security.NoSuchAlgorithmException, java.security.NoSuchProviderException, NoSuchPaddingException
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 cipher providerProvider
public final java.security.Provider getProvider()
public final java.lang.String getAlgorithm()
This is the same name that was specified in one of the getInstance calls that created this Cipher object.
public final int getBlockSize()
public final int getOutputSize(int inputLen) throws java.lang.IllegalStateException
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.
inputLen
- the input length (in bytes)public final byte[] getIV()
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.
public final java.security.AlgorithmParameters getParameters()
The returned parameters may be the same that were used to initialise 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 initialised with any.
public final void init(int opmode, java.security.Key key) throws java.security.InvalidKeyException
The cipher is initialised for encryption or decryption, depending on the value of opmode.
If this cipher requires any algorithm parameters that cannot be derived from the give key, the underlying cipher implementation is supposed to generate the required parameters itself (using provider0specific default or random values) if it is being initialised for encryption, and raise and InvalidKeyException if it is being initialised for decryption. 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 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 initialised, it loses all previously acquired state. In other words, initialising a Cipher is equivalent to creating a new instance of that Cipher and initialising it.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)key
- the keypublic final void init(int opmode, java.security.Key key, java.security.SecureRandom random) throws java.security.InvalidKeyException
The cipher is initialised for encryption or decryption, depending on the value of opmode.
If this cipher requires any algorithm parameters that cannot be derived from the give key, the underlying cipher implementation is supposed to generate the required parameters itself (using provider0specific default or random values) if it is being initialised for encryption, and raise and InvalidKeyException if it is being initialised for decryption. 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 from random.
Note that when a Cipher object is initialised, it loses all previously acquired state. In other words, initialising a Cipher is equivalent to creating a new instance of that Cipher and initialising it.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)key
- the encryption keyrandom
- the source of randomnesspublic final void init(int opmode, java.security.Key key, java.security.spec.AlgorithmParameterSpec params) throws java.security.InvalidKeyException, java.security.InvalidAlgorithmParameterException
The cipher is initialised for encryption or decryption, 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 by itself (using provider-specific default or random values) if it is being initialised for encryption, and raise an InvalidAlgorithmParameterException if it being initialised for decryption. 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 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 initialised, it loses all previously acquired state. In other words, initialising a Cipher is equivalent to creating a new instance of that Cipher and initialising it.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)key
- the encryption keyparams
- the algorithm parameterspublic final void init(int opmode, java.security.Key key, java.security.spec.AlgorithmParameterSpec params, java.security.SecureRandom random) throws java.security.InvalidKeyException, java.security.InvalidAlgorithmParameterException
The cipher is initialised for encryption or decryption, 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 by itself (using provider-specific default or random values) if it is being initialised for encryption, and raise an InvalidAlgorithmParameterException if it being initialised for decryption. 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 from random.
Note that when a Cipher object is initialised, it loses all previously-acquired state. In other words, initialising a Cipher is equivalent to creating a new instance of that Cipher, and initialising it.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)key
- the encryption keyparams
- the algorithm parametersrandom
- the source of randomnesspublic final void init(int opmode, java.security.Key key, java.security.AlgorithmParameters params) throws java.security.InvalidKeyException, java.security.InvalidAlgorithmParameterException
The cipher is initialised for encryption or decryption, 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 by itself (using provider-specific default or random values) if it is being initialised for encryption, and raise an InvalidAlgorithmParameterException if it being initialised for decryption. 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 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 initialised, it loses all previously-acquired state. In other words, initialising a Cipher is equivalent to creating a new instance of that Cipher and initialising it.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)key
- the encryption keyparams
- the algorithm parameterspublic final void init(int opmode, java.security.Key key, java.security.AlgorithmParameters params, java.security.SecureRandom random) throws java.security.InvalidKeyException, java.security.InvalidAlgorithmParameterException
The cipher is initialised for encryption or decryption, 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 by itself (using provider-specific default or random values) if it is being initialised for encryption, and raise an InvalidAlgorithmParameterException if it being initialised for decryption. 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, it will get them from random.
Note that when a Cipher object is initialised, it loses all previously-acquired state. In other words, initialising a Cipher is equivalent to creating a new instance of that Cipher and initialising it.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)key
- the encryption keyparams
- the algorithm parametersrandom
- the source of randomnesspublic final byte[] update(byte[] input) throws java.lang.IllegalStateException
The bytes in the input buffer are processed, and the result is stored in a new buffer.
input
- the input bufferpublic final byte[] update(byte[] input, int inputOffset, int inputLen) throws java.lang.IllegalStateException
The first inputLen bytes in the input buffer, starting at inputOffset inclusive, are processed, and the result is stored in a new buffer.
input
- the input bufferinputOffset
- the offset in input where the input startsinputLen
- the input lengthpublic final int update(byte[] input, int inputOffset, int inputLen, byte[] output) throws java.lang.IllegalStateException, ShortBufferException
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.
input
- - the input bufferinputOffset
- - the offset in input where the input startsinputLen
- - the input lengthoutput
- - the buffer for the resultpublic final int update(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset) throws java.lang.IllegalStateException, ShortBufferException
The first inputLen bytes in the input buffer, starting at inputOffset, are processed, and the result is stored in the output buffer, starting at outputOffset.
If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.
input
- the input bufferinputOffset
- the offset in input where the input startsinputLen
- the input lengthoutput
- the buffer for the resultoutputOffset
- the offset in output where the result is storedpublic final byte[] doFinal() throws java.lang.IllegalStateException, IllegalBlockSizeException, BadPaddingException
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 initialised 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.
public final int doFinal(byte[] output, int outputOffset) throws java.lang.IllegalStateException, IllegalBlockSizeException, ShortBufferException, BadPaddingException
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 the output buffer, starting at outputOffset.
If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.
A call to this method resets this cipher object to the state it was in when previously initialised 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.
output
- the buffer for the resultoutputOffset
- the offset in output where the result is storedpublic final byte[] doFinal(byte[] input) throws java.lang.IllegalStateException, IllegalBlockSizeException, BadPaddingException
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 initialised 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.
input
- - the input bufferpublic final byte[] doFinal(byte[] input, int inputOffset, int inputLen) throws java.lang.IllegalStateException, IllegalBlockSizeException, BadPaddingException
The first inputLen bytes in the input buffer, starting at inputOffset, and any input bytes that may have been buffered during a previous update operation, are processed, with padding (if requested) being applied. The result is stored in a new buffer.
A call to this method resets this cipher object to the state it was in when previously initialised 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.
input
- - the input bufferinputOffset
- - the offset in input where the input startsinputLen
- - the input lengthpublic final int doFinal(byte[] input, int inputOffset, int inputLen, byte[] output) throws java.lang.IllegalStateException, ShortBufferException, IllegalBlockSizeException, BadPaddingException
The first inputLen bytes in the input buffer, starting at inputOffset, and any input bytes that may have been buffered during a previous update operation, are processed, with padding (if requested) being applied. The result is stored in the output buffer.
If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.
A call to this method resets this cipher object to the state it was in when previously initialised 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.
input
- - the input bufferinputOffset
- - the offset in input where the input startsinputLen
- - the input lengthoutput
- - the buffer for the resultpublic final int doFinal(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset) throws java.lang.IllegalStateException, ShortBufferException, IllegalBlockSizeException, BadPaddingException
The first inputLen bytes in the input buffer, starting at inputOffset, and any input bytes that may have been buffered during a previous update operation, are processed, with padding (if requested) being applied. The result is stored in the output buffer, starting at outputOffset.
If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.
A call to this method resets this cipher object to the state it was in when previously initialised 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.
input
- the input bufferinputOffset
- the offset in input where the input startsinputLen
- the input lengthoutput
- the buffer for the resultoutputOffset
- the offset in output where the result is stored
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