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Class javax.crypto.Cipher
java.lang.Object
|
+----javax.crypto.Cipher
- 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 defaults values for 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
-
DECRYPT_MODE
-
-
ENCRYPT_MODE
-
-
ident
-
-
Cipher(CipherSpi, Provider, String)
- Creates a Cipher object.
-
doFinal()
- Finishes a multiple-part encryption or decryption operation,
depending on how this cipher was initialised.
-
doFinal(byte[])
- Encrypts or decrypts data in a single-part operation, or finishes a
multiple-part operation.
-
doFinal(byte[], int)
- Finishes a multiple-part encryption or decryption operation,
depending on how this cipher was initialised.
-
doFinal(byte[], int, int)
- Encrypts or decrypts data in a single-part operation, or finishes
a multiple-part operation.
-
doFinal(byte[], int, int, byte[])
- Encrypts or decrypts data in a single-part operation, or finishes a
multiple-part operation.
-
doFinal(byte[], int, int, byte[], int)
- Encrypts or decrypts data in a single-part operation, or finishes a
multiple-part operation.
-
getAlgorithm()
- Returns the algorithm name of this Cipher object.
-
getBlockSize()
- Returns the block size (in bytes).
-
getInstance(String)
- Generates a Cipher object that implements the specified
transformation.
-
getInstance(String, String)
- Creates a Cipher object that implements the specified transformation,
as supplied by the specified provider.
-
getIV()
- Returns the initialisation vector (IV) in a new buffer.
-
getOutputSize(int)
- 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).
-
getParameters()
- Returns the parameters used with this cipher.
-
getProvider()
- Returns the provider of this Cipher object.
-
init(int, Key)
- Initialises this cipher with a key.
-
init(int, Key, AlgorithmParameters)
- Initialises this cipher with a key and a set of algorithm parameters.
-
init(int, Key, AlgorithmParameters, SecureRandom)
- Initialises this cipher with a key, a set of algorithm parameters,
and a source of randomness.
-
init(int, Key, AlgorithmParameterSpec)
- Initialises this cipher with a key and a set of algorithm parameters.
-
init(int, Key, AlgorithmParameterSpec, SecureRandom)
- Initialises this cipher with a key, a set of algorithm parameters,
and a source of randomness.
-
init(int, Key, SecureRandom)
- Initialises this cipher with a key and a source of randomness.
-
update(byte[])
- Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialised), processing another
data part.
-
update(byte[], int, int)
- Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialised), processing another
data part.
-
update(byte[], int, int, byte[])
- Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialised), processing another
data part.
-
update(byte[], int, int, byte[], int)
- Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialised), processing another
data part.
ident
public static final String ident
ENCRYPT_MODE
public static final int ENCRYPT_MODE
DECRYPT_MODE
public static final int DECRYPT_MODE
Cipher
protected Cipher(CipherSpi cipherSpi,
Provider provider,
String transformation)
- Creates a Cipher object.
- Parameters:
- cipherSpi - the delegate
- provider - the provider
- transformation - the transformation
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 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.
- 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 requested algorithm is
not available in the default provider package or any of the
other provider packages that were searched.
- Throws: NoSuchPaddingException
- if transformation contains a
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 cipher provider
- Returns:
- a cipher that implements the requested transformation
- Throws: NoSuchAlgorithmException
- if the requested algorithm is
not available
- Throws: NoSuchProviderException
- if the requested provider is
not available
- Throws: NoSuchPaddingException
- if the requested padding mechanism
is not available
- See Also:
- Provider
getProvider
public final Provider getProvider()
- Returns the provider of this Cipher object.
- Returns:
- 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 initialised)
getIV
public final byte[] getIV()
- Returns the initialisation 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 initialisation 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 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.
- Returns:
- the parameters used with this cipher, or null if this cipher
does not use any parameters.
init
public final void init(int opmode,
Key key) throws InvalidKeyException
- Initialises this cipher with a key.
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.
- Parameters:
- opmode - the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)
- key - the key
- Throws: InvalidKeyException
- if the given key is inappropriate
for initialising this cipher, or if this cipher is being
initialised for decryption 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
- Initialises this cipher with a key and a source of randomness.
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.
- Parameters:
- opmode - the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)
- key - the encryption key
- random - the source of randomness
- Throws: InvalidKeyException
- if the given key is inappropriate
for initialising this cipher, or if the cipher is being
initialised for decryption 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
- Initialises this cipher with a key and a set of algorithm parameters.
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.
- Parameters:
- opmode - the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)
- key - the encryption key
- params - the algorithm parameters
- Throws: InvalidKeyException
- if the given key is inappropriate
for initialising this cipher.
- Throws: InvalidAlgorithmParameterException
- if the given algorithm
parameters are inappropriate for this cipher, or if this
cipher is being initialised for decryption and requires
algorithm parameters and params is null.
init
public final void init(int opmode,
Key key,
AlgorithmParameterSpec params,
SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException
- Initialises this cipher with a key, a set of algorithm parameters,
and a source of randomness.
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.
- Parameters:
- opmode - the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)
- key - the encryption key
- params - the algorithm parameters
- random - the source of randomness
- Throws: InvalidKeyException
- if the given key is inappropriate
for initialising this cipher
- Throws: InvalidAlgorithmParameterException
- if the given algorithm
parameters are inappropriate for this cipher, or if this
cipher is being initialised for decryption and requires
algorithm parameters and params is null.
init
public final void init(int opmode,
Key key,
AlgorithmParameters params) throws InvalidKeyException, InvalidAlgorithmParameterException
- Initialises this cipher with a key and a set of algorithm parameters.
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.
- Parameters:
- opmode - the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)
- key - the encryption key
- params - the algorithm parameters
- Throws: InvalidKeyException
- - if the given key is
inappropriate for initialising this cipher
- Throws: InvalidAlgorithmParameterException
- if the given algorithm
parameters are inappropriate for this cipher, or if this
cipher is being initialised for decryption and requires
algorithm parameters and params is null.
init
public final void init(int opmode,
Key key,
AlgorithmParameters params,
SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException
- Initialises this cipher with a key, a set of algorithm parameters,
and a source of randomness.
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.
- Parameters:
- opmode - the operation mode of this cipher (this is either
ENCRYPT_MODE or DECRYPT_MODE)
- key - the encryption key
- params - the algorithm parameters
- random - the source of randomness
- Throws: InvalidKeyException
- if the given key is
inappropriate for initialising this cipher
- Throws: InvalidAlgorithmParameterException
- if the given algorithm
parameters are inappropriate for this cipher, or if this
cipher is being initialised for decryption and requires
algorithm parameters and params is null.
update
public final byte[] update(byte input[]) throws IllegalStateException
- Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialised), processing another
data part.
The bytes in the input buffer are processed, and the result is
stored in a new buffer.
- 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 initialised)
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 initialised), processing another
data part.
The first inputLen bytes in the input buffer, starting at
inputOffset inclusive, are processed, and the result is stored in
a new buffer.
- Parameters:
- input - the input buffer
- inputOffset - the offset in input where the input starts
- inputLen - the input length
- Returns:
- the new buffer with the result, or null if the underlying
cipher is a block cipher and the input data is too short to
result in a new block.
- Throws: IllegalStateException
- if this cipher is in a wrong state
(e.g., has not been initialised)
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 initialised), 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.
- 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 initialised)
- Throws: ShortBufferException
- if the given output buffer is
too small to hold the result.
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 initialised), processing another
data part.
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.
- 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 initialised)
- Throws: ShortBufferException
- if the given output buffer is
too small to hold the result
doFinal
public final byte[] doFinal() throws IllegalStateException, IllegalBlockSizeException, BadPaddingException
- Finishes a multiple-part encryption or decryption operation,
depending on how this cipher was initialised.
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.
- Returns:
- s the new buffer with the result
- Throws: IllegalStateException
- if this cipher is in a wrong state
(e.g., has not been initialised)
- Throws: IllegalBlockSizeException
- if this cipher is a block
cipher, no padding has been requested (only in encryption
mode), and the total input length of the data processed by
this cipher is not a multiple of block size
- Throws: 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 initialised.
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.
- 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 initialised)
- Throws: IllegalBlockSizeException
- if this cipher is a block
cipher, no padding has been requested (only in encryption mode),
and the total input length of the data processed by this cipher
is not a multiple of block size
- Throws: ShortBufferException
- if the given output buffer is too
small to hold the result
- Throws: 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 initialised.
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.
- Parameters:
- input - - the input buffer
- Returns:
- s the new buffer with the result
- Throws: IllegalStateException
- if this cipher is in a wrong state
(e.g., has not been initialised)
- Throws: IllegalBlockSizeException
- if this cipher is a block
cipher, no padding has been requested (only in encryption mode),
and the total input length of the data processed by this cipher
is not a multiple of block size
- Throws: 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 initialised.
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.
- 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 initialised)
- Throws: IllegalBlockSizeException
- if this cipher is a block
cipher, no padding has been requested (only in encryption mode),
and the total input length of the data processed by this cipher
is not a multiple of block size
- Throws: 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
- 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 initialised.
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.
- 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 initialised)
- Throws: IllegalBlockSizeException
- if this cipher is a block
cipher, no padding has been requested (only in encryption mode),
and the total input length of the data processed by this cipher
is not a multiple of block size
- Throws: ShortBufferException
- if the given output buffer is too
small to hold the result
- Throws: 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
- 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 initialised.
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.
- 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 initialised)
- Throws: IllegalBlockSizeException
- if this cipher is a block
cipher, no padding has been requested (only in encryption mode),
and the total input length of the data processed by this cipher
is not a multiple of block size
- Throws: ShortBufferException
- if the given output buffer is too
small to hold the result
- Throws: 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
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