APIdia Launch Partner
Top Description Fields Constructors Methods
com.sun.crypto.provider

public sealed Class ARCFOURCipher

extends CipherSpi
permits PBEWithSHA1AndRC4
Class Inheritance
Known Direct Subclasses
com.sun.crypto.provider.PKCS12PBECipherCore.PBEWithSHA1AndRC4
Imports
java.security.*, java.security.spec.AlgorithmParameterSpec, java.util.Arrays, javax.crypto.*

Implementation of the ARCFOUR cipher, an algorithm apparently compatible with RSA Security's RC4(tm) cipher. The description of this algorithm was taken from Bruce Schneier's book Applied Cryptography, 2nd ed., section 17.1. We support keys from 40 to 1024 bits. ARCFOUR would allow for keys shorter than 40 bits, but that is too insecure for us to permit. Note that we subclass CipherSpi directly and do not use the CipherCore framework. That was designed to simplify implementation of block ciphers and does not offer any advantages for stream ciphers such as ARCFOUR.
Author
Andreas Sterbenz
Since
1.5

Field Summary

Modifier and TypeField and Description
private int
private int
private byte[]
private final int[]
S

Constructor Summary

AccessConstructor and Description
public

Method Summary

Modifier and TypeMethod and Description
private void
crypt(byte[] in, int inOfs, int inLen, byte[] out, int outOfs)

protected byte[]
engineDoFinal(byte[] in, int inOfs, int inLen)

Implements abstract javax.crypto.CipherSpi.engineDoFinal.

Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.

protected int
engineDoFinal(byte[] in, int inOfs, int inLen, byte[] out, int outOfs)

Implements abstract javax.crypto.CipherSpi.engineDoFinal.

Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.

protected int
engineGetBlockSize()

Implements abstract javax.crypto.CipherSpi.engineGetBlockSize.

Returns the block size (in bytes).

protected byte[]
engineGetIV()

Implements abstract javax.crypto.CipherSpi.engineGetIV.

Returns the initialization vector (IV) in a new buffer.

protected int
engineGetKeySize(Key key)

Overrides javax.crypto.CipherSpi.engineGetKeySize.

Returns the key size of the given key object in bits.

protected int
engineGetOutputSize(int inputLen)

Implements abstract javax.crypto.CipherSpi.engineGetOutputSize.

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).

protected AlgorithmParameters
engineGetParameters()

Implements abstract javax.crypto.CipherSpi.engineGetParameters.

Returns the parameters used with this cipher.

protected void
engineInit(int opmode, Key key, SecureRandom random)

Implements abstract javax.crypto.CipherSpi.engineInit.

Initializes this CipherSpi object with a key and a source of randomness.

protected void
engineInit(int opmode, Key key, AlgorithmParameterSpec params, SecureRandom random)

Implements abstract javax.crypto.CipherSpi.engineInit.

Initializes this CipherSpi object with a key, a set of algorithm parameters, and a source of randomness.

protected void
engineInit(int opmode, Key key, AlgorithmParameters params, SecureRandom random)

Implements abstract javax.crypto.CipherSpi.engineInit.

Initializes this CipherSpi object with a key, a set of algorithm parameters, and a source of randomness.

protected void
engineSetMode(String mode)

Implements abstract javax.crypto.CipherSpi.engineSetMode.

Sets the mode of this cipher.

protected void
engineSetPadding(String padding)

Implements abstract javax.crypto.CipherSpi.engineSetPadding.

Sets the padding mechanism of this cipher.

protected Key
engineUnwrap(byte[] wrappedKey, String algorithm, int type)

Overrides javax.crypto.CipherSpi.engineUnwrap.

Unwrap a previously wrapped key.

protected byte[]
engineUpdate(byte[] in, int inOfs, int inLen)

Implements abstract javax.crypto.CipherSpi.engineUpdate.

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

protected int
engineUpdate(byte[] in, int inOfs, int inLen, byte[] out, int outOfs)

Implements abstract javax.crypto.CipherSpi.engineUpdate.

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

protected byte[]
private static byte[]
private void
init(byte[] key)

private void
init(int opmode, Key key)

Inherited from javax.crypto.CipherSpi:
engineDoFinalengineUpdateengineUpdateAADengineUpdateAAD

Field Detail

isback to summary
private int is
jsback to summary
private int js
lastKeyback to summary
private byte[] lastKey
Sback to summary
private final int[] S

Constructor Detail

ARCFOURCipherback to summary
public ARCFOURCipher()

Method Detail

cryptback to summary
private void crypt(byte[] in, int inOfs, int inLen, byte[] out, int outOfs)
engineDoFinalback to summary
protected byte[] engineDoFinal(byte[] in, int inOfs, int inLen)

Implements abstract javax.crypto.CipherSpi.engineDoFinal.

Doc from javax.crypto.CipherSpi.engineDoFinal.

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 CipherSpi object 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. If an AEAD mode (such as GCM or CCM) is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in a new buffer.

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

Note

if any exception is thrown, this CipherSpi object may need to be reset before it can be used again.

engineDoFinalback to summary
protected int engineDoFinal(byte[] in, int inOfs, int inLen, byte[] out, int outOfs) throws ShortBufferException

Implements abstract javax.crypto.CipherSpi.engineDoFinal.

Doc from javax.crypto.CipherSpi.engineDoFinal.

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 CipherSpi object 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. If an AEAD mode such as GCM or CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. 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.

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

Note

if any exception is thrown, this CipherSpi object may need to be reset before it can be used again.

Exceptions
ShortBufferException:
if the given output buffer is too small to hold the result
engineGetBlockSizeback to summary
protected int engineGetBlockSize()

Implements abstract javax.crypto.CipherSpi.engineGetBlockSize.

Doc from javax.crypto.CipherSpi.engineGetBlockSize.

Returns the block size (in bytes).

engineGetIVback to summary
protected byte[] engineGetIV()

Implements abstract javax.crypto.CipherSpi.engineGetIV.

Doc from javax.crypto.CipherSpi.engineGetIV.

Returns the initialization 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.

engineGetKeySizeback to summary
protected int engineGetKeySize(Key key) throws InvalidKeyException

Overrides javax.crypto.CipherSpi.engineGetKeySize.

Doc from javax.crypto.CipherSpi.engineGetKeySize.

Returns the key size of the given key object in bits.

This concrete method has been added to this previously-defined abstract class. It throws an UnsupportedOperationException if it is not overridden by the provider.

Exceptions
InvalidKeyException:
if key is invalid
engineGetOutputSizeback to summary
protected int engineGetOutputSize(int inputLen)

Implements abstract javax.crypto.CipherSpi.engineGetOutputSize.

Doc from javax.crypto.CipherSpi.engineGetOutputSize.

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, padding, and AEAD tagging.

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

engineGetParametersback to summary
protected AlgorithmParameters engineGetParameters()

Implements abstract javax.crypto.CipherSpi.engineGetParameters.

Doc from javax.crypto.CipherSpi.engineGetParameters.

Returns the parameters used with this cipher.

The returned parameters may be the same that were used to initialize this cipher, or may contain additional default or random parameter values used by the underlying cipher implementation. If the required parameters were not supplied and can be generated by the cipher, the generated parameters are returned. Otherwise, null is returned.

engineInitback to summary
protected void engineInit(int opmode, Key key, SecureRandom random) throws InvalidKeyException

Implements abstract javax.crypto.CipherSpi.engineInit.

Doc from javax.crypto.CipherSpi.engineInit.

Initializes this CipherSpi object with a key and a source of randomness.

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

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from random.

Note that when a CipherSpi object is initialized, it loses all previously-acquired state. In other words, initializing a CipherSpi object is equivalent to creating a new instance of that CipherSpi object and initializing it.

Exceptions
InvalidKeyException:
if the given key is inappropriate for initializing this cipher, or requires algorithm parameters that cannot be determined from the given key
engineInitback to summary
protected void engineInit(int opmode, Key key, AlgorithmParameterSpec params, SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException

Implements abstract javax.crypto.CipherSpi.engineInit.

Doc from javax.crypto.CipherSpi.engineInit.

Initializes this CipherSpi object with a key, a set of algorithm parameters, and a source of randomness.

The CipherSpi object 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 requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from random.

Note that when a CipherSpi object is initialized, it loses all previously-acquired state. In other words, initializing a CipherSpi object is equivalent to creating a new instance of that CipherSpi object and initializing it.

Exceptions
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 requires algorithm parameters and params is null
engineInitback to summary
protected void engineInit(int opmode, Key key, AlgorithmParameters params, SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException

Implements abstract javax.crypto.CipherSpi.engineInit.

Doc from javax.crypto.CipherSpi.engineInit.

Initializes this CipherSpi object with a key, a set of algorithm parameters, and a source of randomness.

The CipherSpi object 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 requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from random.

Note that when a CipherSpi object is initialized, it loses all previously-acquired state. In other words, initializing a CipherSpi object is equivalent to creating a new instance of that CipherSpi object and initializing it.

Exceptions
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 requires algorithm parameters and params is null
engineSetModeback to summary
protected void engineSetMode(String mode) throws NoSuchAlgorithmException

Implements abstract javax.crypto.CipherSpi.engineSetMode.

Doc from javax.crypto.CipherSpi.engineSetMode.

Sets the mode of this cipher.

Exceptions
NoSuchAlgorithmException:
if the requested cipher mode does not exist
engineSetPaddingback to summary
protected void engineSetPadding(String padding) throws NoSuchPaddingException

Implements abstract javax.crypto.CipherSpi.engineSetPadding.

Doc from javax.crypto.CipherSpi.engineSetPadding.

Sets the padding mechanism of this cipher.

Exceptions
NoSuchPaddingException:
if the requested padding mechanism does not exist
engineUnwrapback to summary
protected Key engineUnwrap(byte[] wrappedKey, String algorithm, int type) throws InvalidKeyException, NoSuchAlgorithmException

Overrides javax.crypto.CipherSpi.engineUnwrap.

Doc from javax.crypto.CipherSpi.engineUnwrap.

Unwrap a previously wrapped key.

This concrete method has been added to this previously-defined abstract class. (For backwards compatibility, it cannot be abstract.) It may be overridden by a provider to unwrap a previously wrapped key. Such an override is expected to throw an InvalidKeyException if the given wrapped key cannot be unwrapped. If this method is not overridden, it always throws an UnsupportedOperationException.

Exceptions
InvalidKeyException:
if wrappedKey does not represent a wrapped key of type wrappedKeyType for the wrappedKeyAlgorithm
NoSuchAlgorithmException:
if no installed providers can create keys of type wrappedKeyType for the wrappedKeyAlgorithm
engineUpdateback to summary
protected byte[] engineUpdate(byte[] in, int inOfs, int inLen)

Implements abstract javax.crypto.CipherSpi.engineUpdate.

Doc from javax.crypto.CipherSpi.engineUpdate.

Continues a multiple-part encryption or decryption operation (depending on how this CipherSpi object 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.

engineUpdateback to summary
protected int engineUpdate(byte[] in, int inOfs, int inLen, byte[] out, int outOfs) throws ShortBufferException

Implements abstract javax.crypto.CipherSpi.engineUpdate.

Doc from javax.crypto.CipherSpi.engineUpdate.

Continues a multiple-part encryption or decryption operation (depending on how this CipherSpi object 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.

Exceptions
ShortBufferException:
if the given output buffer is too small to hold the result
engineWrapback to summary
protected byte[] engineWrap(Key key) throws IllegalBlockSizeException, InvalidKeyException

Overrides javax.crypto.CipherSpi.engineWrap.

Doc from javax.crypto.CipherSpi.engineWrap.

Wrap a key.

This concrete method has been added to this previously-defined abstract class. (For backwards compatibility, it cannot be abstract.) It may be overridden by a provider to wrap a key. Such an override is expected to throw an IllegalBlockSizeException or InvalidKeyException (under the specified circumstances), if the given key cannot be wrapped. If this method is not overridden, it always throws an UnsupportedOperationException.

Exceptions
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)
getEncodedKeyback to summary
private static byte[] getEncodedKey(Key key) throws InvalidKeyException
initback to summary
private void init(byte[] key)
initback to summary
private void init(int opmode, Key key) throws InvalidKeyException