Class javax.crypto.CipherSpi
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Class javax.crypto.CipherSpi
java.lang.Object
|
+----javax.crypto.CipherSpi
- public class CipherSpi
- extends Object
A parent class for the provider implementations of encryption/decryption
objects.
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ident
-
-
CipherSpi()
-
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engineDoFinal(byte[], int, int)
- Encrypts or decrypts data in a single-part operation, or
finishes a multiple-part operation.
-
engineDoFinal(byte[], int, int, byte[], int)
- Encrypts or decrypts data in a single-part operation, or finishes
a multiple-part operation.
-
engineGetBlockSize()
- Returns the block size (in bytes).
-
engineGetIV()
- Returns the initialisation vector (IV) in a new buffer.
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engineGetOutputSize(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).
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engineInit(int, Key, AlgorithmParameterSpec, SecureRandom)
- Initialises this cipher with a key, a set of algorithm parameters,
and a source of randomness.
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engineInit(int, Key, SecureRandom)
- Initialises this cipher with a key and a source of randomness.
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engineSetMode(String)
- Sets the mode of this cipher.
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engineSetPadding(String)
- Sets the padding mechanism of this cipher.
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engineUpdate(byte[], int, int)
- Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialised), processing another
data part.
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engineUpdate(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 final static String ident
CipherSpi
public CipherSpi()
engineSetMode
protected abstract void engineSetMode(String mode) throws NoSuchAlgorithmException
- Sets the mode of this cipher.
- Parameters:
- mode - the cipher mode
- Throws: NoSuchAlgorithmException
- if the requested cipher mode
does not exist
engineSetPadding
protected abstract void engineSetPadding(String padding) throws NoSuchPaddingException
- Sets the padding mechanism of this cipher.
- Parameters:
- padding - the padding mechanism
- Throws: NoSuchPaddingException
- if the requested padding
mechanism does not exist.
engineGetBlockSize
protected abstract int engineGetBlockSize()
- Returns the block size (in bytes).
- Returns:
- the block size (in bytes), or 0 if the underlying
algorithm is not a block cipher
engineGetOutputSize
protected abstract int engineGetOutputSize(int inputLen)
- Returns the length in bytes that an output buffer would need to be
in order to hold the result of the next update or doFinal operation,
given the input length inputLen (in bytes).
This call takes into account any unprocessed (buffered) data from a
previous update call, 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)
engineGetIV
protected abstract byte[] engineGetIV()
- Returns the initialisation vector (IV) in a new buffer.
This is useful in the context of password-based encryption or
decryption, where the IV is derived from a user-provided passphrase.
- 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.
engineInit
protected abstract void engineInit(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 an initialisation 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
initialising 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 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
engineInit
protected abstract void engineInit(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 (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
engineUpdate
protected abstract byte[] engineUpdate(byte in[],
int inOff,
int inLen)
- 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 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.
engineUpdate
protected abstract int engineUpdate(byte in[],
int inOff,
int inLen,
byte out[],
int outOff) throws 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: ShortBufferException
- if the given output buffer is too
small to hold the result
engineDoFinal
protected abstract byte[] engineDoFinal(byte input[],
int inputOffset,
int inputLen) throws 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.
The cipher is reset to its initial state (uninitialised) after
this call.
- 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: 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.
engineDoFinal
protected abstract int engineDoFinal(byte in[],
int inOff,
int inLen,
byte out[],
int outOff) 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 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.
- 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:
- s the number of bytes stored in output
- 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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