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java.lang.Object | +----javax.crypto.Cipher
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" or "algorithm/mode/padding" (in the former case, provider-specific defaults are used for mode and padding). For example, "DES/CBC/PKCS5Padding" represents a valid transformation.
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.)
Field Summary | |
static int | DECRYPT_MODE
|
static int | ENCRYPT_MODE
|
Constructor Summary | |
Cipher(CipherSpi cipherSpi,
java.security.Provider provider,
java.lang.String transformation)
|
Method Summary | |
byte[] | doFinal()
|
int | doFinal(byte[] output,
int outputOffset)
|
byte[] | doFinal(byte[] input)
|
byte[] | doFinal(byte[] input,
int inputOffset,
int inputLen)
|
int | doFinal(byte[] input,
int inputOffset,
int inputLen,
byte[] output)
|
int | doFinal(byte[] input,
int inputOffset,
int inputLen,
byte[] output,
int outputOffset)
|
int | getBlockSize()
|
static Cipher | getInstance(java.lang.String transformation)
Cipher object that implements the specified
transformation.
|
static Cipher | getInstance(java.lang.String transformation,
java.lang.String provider)
Cipher object that implements the specified
transformation, as supplied by the specified provider.
|
byte[] | getIV()
|
int | getOutputSize(int inputLen)
update or
doFinal operation, given the input length
inputLen (in bytes).
|
java.security.Provider | getProvider()
Cipher object.
|
void | init(int opmode,
java.security.Key key)
|
void | init(int opmode,
java.security.Key key,
java.security.SecureRandom random)
|
void | init(int opmode,
java.security.Key key,
java.security.spec.AlgorithmParameterSpec params)
|
void | init(int opmode,
java.security.Key key,
java.security.spec.AlgorithmParameterSpec params,
java.security.SecureRandom random)
|
byte[] | update(byte[] input)
|
byte[] | update(byte[] input,
int inputOffset,
int inputLen)
|
int | update(byte[] input,
int inputOffset,
int inputLen,
byte[] output)
|
int | update(byte[] input,
int inputOffset,
int inputLen,
byte[] output,
int outputOffset)
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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 delegate
provider
- the provider
transformation
- the transformation
Method Detail |
public static final Cipher getInstance(java.lang.String transformation) throws java.security.NoSuchAlgorithmException, NoSuchPaddingException
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.
transformation
- the string representation of the requested
transformation, e.g., DES/CBC/PKCS5Padding
public static final Cipher getInstance(java.lang.String transformation, java.lang.String provider) throws java.security.NoSuchAlgorithmException, java.security.NoSuchProviderException, NoSuchPaddingException
Cipher
object that implements the specified
transformation, as supplied by the specified provider.
transformation
- the string representation of the requested
transformation, e.g., DES/CBC/PKCS5Padding
provider
- the name of the cipher provider
public final java.security.Provider getProvider()
Cipher
object.Cipher
objectpublic final int getBlockSize()
public final int getOutputSize(int inputLen) throws java.lang.IllegalStateException
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.
inputLen
- the input length (in bytes)
public final byte[] getIV()
This is useful in the case where a random IV has been created (see init), or in the context of password-based encryption or decryption, where the IV is derived from a user-provided passphrase.
public final void init(int opmode, java.security.Key key) throws java.security.InvalidKeyException
The cipher is initialized for encryption or decryption, depending on
the value of opmode
.
If this cipher requires an initialization vector (IV), it will get it from a system-provided source of randomness. The random IV can be retrieved using getIV. This behaviour should only be used in encryption mode, however. When initializing a cipher that requires an IV for decryption, the IV (same IV that was used for encryption) must be provided explicitly as a parameter, in order to get the correct result.
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.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE
or DECRYPT_MODE
)
key
- the key
public final void init(int opmode, java.security.Key key, java.security.SecureRandom random) throws java.security.InvalidKeyException
The cipher is initialized for encryption or decryption, depending on
the value of opmode
.
If this cipher requires an initialization vector (IV), it will get
it from random
. The random IV can be
retrieved using getIV.
This behaviour should only be used in encryption mode, however.
When initializing a cipher that requires an IV for decryption, the IV
(same IV that was used for encryption) must be provided explicitly as a
parameter, in order to get the correct result.
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.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE
or DECRYPT_MODE
)
key
- the encryption key
random
- the source of randomness
public final void init(int opmode, java.security.Key key, java.security.spec.AlgorithmParameterSpec params) throws java.security.InvalidKeyException, java.security.InvalidAlgorithmParameterException
The cipher is initialized for encryption or decryption, depending on
the value of opmode
.
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.
opmode
- the operation mode of this cipher (this is either
ENCRYPT_MODE
or DECRYPT_MODE
)
key
- the encryption key
params
- the algorithm parameters
public 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 initialized for encryption or decryption, depending on
the value of opmode
.
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 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.
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
public 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 buffer
public final byte[] update(byte[] input, int inputOffset, int inputLen) throws java.lang.IllegalStateException
The first inputLen
bytes in the input
buffer, starting at inputOffset
, are processed, and the
result is stored in a new buffer.
input
- the input buffer
inputOffset
- the offset in input
where the input
starts
inputLen
- the input length
public 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
, 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 buffer
inputOffset
- the offset in input
where the input
starts
inputLen
- the input length
output
- the buffer for the result
output
public 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 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
output
public 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.
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.
output
- the buffer for the result
outputOffset
- the offset in output
where the result
is stored
output
public 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.
input
- the input buffer
public 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.
input
- the input buffer
inputOffset
- the offset in input
where the input
starts
inputLen
- the input length
public 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.
input
- the input buffer
inputOffset
- the offset in input
where the input
starts
inputLen
- the input length
output
- the buffer for the result
output
public 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.
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
output
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