Cipher(CipherSpi cipherSpi,
    String transformation) 
{
        this.spi = cipherSpi;
        this.transformation = transformation;
        this.cryptoPerm = CryptoAllPermission.INSTANCE;
        this.lock = null;
}

Creates a Cipher object. Called internally and by NullCipher.

Parameters:

cipherSpi - the delegate

transformation - the transformation

 protected Cipher(CipherSpi cipherSpi,
    Provider provider,
    String transformation) 
{
                         
        // See bug 4341369 & 4334690 for more info.
        // If the caller is trusted, then okey.
        // Otherwise throw a NullPointerException.
        if (!JceSecurityManager.INSTANCE.isCallerTrusted()) {
            throw new NullPointerException();
        }
        this.spi = cipherSpi;
        this.provider = provider;
        this.transformation = transformation;
        this.cryptoPerm = CryptoAllPermission.INSTANCE;
        this.lock = null;
}

Creates a Cipher object.

Parameters:

cipherSpi - the delegate

provider - the provider

transformation - the transformation

  void chooseFirstProvider() 
{
                                 
        if (spi != null) {
            return;
        }
        synchronized (lock) {
            if (spi != null) {
                return;
            }
            if (debug != null) {
                int w = --warnCount;
                if (w  >= 0) {
                    debug.println("Cipher.init() not first method "
                        + "called, disabling delayed provider selection");
                    if (w == 0) {
                        debug.println("Further warnings of this type will "
                            + "be suppressed");
                    }
                    new Exception("Call trace").printStackTrace();
                }
            }
            Exception lastException = null;
            while ((firstService != null) || serviceIterator.hasNext()) {
                Service s;
                CipherSpi thisSpi;
                if (firstService != null) {
                    s = firstService;
                    thisSpi = firstSpi;
                    firstService = null;
                    firstSpi = null;
                } else {
                    s = (Service)serviceIterator.next();
                    thisSpi = null;
                }
                if (JceSecurity.canUseProvider(s.getProvider()) == false) {
                    continue;
                }
                Transform tr = getTransform(s, transforms);
                if (tr == null) {
                    // should never happen
                    continue;
                }
                if (tr.supportsModePadding(s) == S_NO) {
                    continue;
                }
                try {
                    if (thisSpi == null) {
                        Object obj = s.newInstance(null);
                        if (obj instanceof CipherSpi == false) {
                            continue;
                        }
                        thisSpi = (CipherSpi)obj;
                    }
                    tr.setModePadding(thisSpi);
                    initCryptoPermission();
                    spi = thisSpi;
                    provider = s.getProvider();
                    // not needed any more
                    firstService = null;
                    serviceIterator = null;
                    transforms = null;
                    return;
                } catch (Exception e) {
                    lastException = e;
                }
            }
            ProviderException e = new ProviderException
                    ("Could not construct CipherSpi instance");
            if (lastException != null) {
                e.initCause(lastException);
            }
            throw e;
        }
}

Choose the Spi from the first provider available. Used if delayed provider selection is not possible because init() is not the first method called.

 public final byte[] doFinal() throws IllegalBlockSizeException, BadPaddingException 
{
        checkCipherState();
        chooseFirstProvider();
        return spi.engineDoFinal(null, 0, 0);
}

Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.

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.

Upon finishing, this method resets this cipher object to the state it was in when previously initialized 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.

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

 public final byte[] doFinal(byte[] input) throws IllegalBlockSizeException, BadPaddingException 
{
        checkCipherState();
        // Input sanity check
        if (input == null) {
            throw new IllegalArgumentException("Null input buffer");
        }
        chooseFirstProvider();
        return spi.engineDoFinal(input, 0, input.length);
}

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 initialized.

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.

Upon finishing, this method resets this cipher object to the state it was in when previously initialized 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.

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

 public final int doFinal(byte[] output,
    int outputOffset) throws IllegalBlockSizeException, ShortBufferException, BadPaddingException 
{
        checkCipherState();
        // Input sanity check
        if ((output == null) || (outputOffset <  0)) {
            throw new IllegalArgumentException("Bad arguments");
        }
        chooseFirstProvider();
        return spi.engineDoFinal(null, 0, 0, output, outputOffset);
}

Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.

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 inclusive.

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.

Upon finishing, this method resets this cipher object to the state it was in when previously initialized 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.

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

 public final int doFinal(ByteBuffer input,
    ByteBuffer output) throws IllegalBlockSizeException, ShortBufferException, BadPaddingException 
{
        checkCipherState();
        if ((input == null) || (output == null)) {
            throw new IllegalArgumentException("Buffers must not be null");
        }
        if (input == output) {
            throw new IllegalArgumentException("Input and output buffers must "
                + "not be the same object, consider using buffer.duplicate()");
        }
        if (output.isReadOnly()) {
            throw new ReadOnlyBufferException();
        }
        chooseFirstProvider();
        return spi.engineDoFinal(input, output);
}

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 initialized.

All input.remaining() bytes starting at input.position() are processed. The result is stored in the output buffer. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. The output buffer's position will have advanced by n, where n is the value returned by this method; the output buffer's limit will not have changed.

If output.remaining() bytes are insufficient 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.

Upon finishing, this method resets this cipher object to the state it was in when previously initialized 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.

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

Note: this method should be copy-safe, which means the input and output buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

 public final byte[] doFinal(byte[] input,
    int inputOffset,
    int inputLen) throws IllegalBlockSizeException, BadPaddingException 
{
        checkCipherState();
        // Input sanity check
        if (input == null || inputOffset <  0
            || inputLen  > (input.length - inputOffset) || inputLen <  0) {
            throw new IllegalArgumentException("Bad arguments");
        }
        chooseFirstProvider();
        return spi.engineDoFinal(input, inputOffset, inputLen);
}

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 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. The result is stored in a new buffer.

Upon finishing, this method resets this cipher object to the state it was in when previously initialized 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.

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

 public final int doFinal(byte[] input,
    int inputOffset,
    int inputLen,
    byte[] output) throws IllegalBlockSizeException, ShortBufferException, BadPaddingException 
{
        checkCipherState();
        // Input sanity check
        if (input == null || inputOffset <  0
            || inputLen  > (input.length - inputOffset) || inputLen <  0) {
            throw new IllegalArgumentException("Bad arguments");
        }
        chooseFirstProvider();
        return spi.engineDoFinal(input, inputOffset, inputLen,
                                       output, 0);
}

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 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. 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.

Upon finishing, this method resets this cipher object to the state it was in when previously initialized 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.

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

Note: this method should be copy-safe, which means the input and output buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

 public final int doFinal(byte[] input,
    int inputOffset,
    int inputLen,
    byte[] output,
    int outputOffset) throws IllegalBlockSizeException, ShortBufferException, BadPaddingException 
{
        checkCipherState();
        // Input sanity check
        if (input == null || inputOffset <  0
            || inputLen  > (input.length - inputOffset) || inputLen <  0
            || outputOffset <  0) {
            throw new IllegalArgumentException("Bad arguments");
        }
        chooseFirstProvider();
        return spi.engineDoFinal(input, inputOffset, inputLen,
                                       output, outputOffset);
}

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 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. 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. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.

Upon finishing, this method resets this cipher object to the state it was in when previously initialized 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.

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

Note: this method should be copy-safe, which means the input and output buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

 public final String getAlgorithm() 
{
        return this.transformation;
}

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..

 public final int getBlockSize() 
{
        chooseFirstProvider();
        return spi.engineGetBlockSize();
}

Returns the block size (in bytes).

 public final ExemptionMechanism getExemptionMechanism() 
{
        chooseFirstProvider();
        return exmech;
}

Returns the exemption mechanism object used with this cipher.

 public final byte[] getIV() 
{
        chooseFirstProvider();
        return spi.engineGetIV();
}

Returns the initialization 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.

 public static final Cipher getInstance(String transformation) throws NoSuchAlgorithmException, NoSuchPaddingException 
{
        List transforms = getTransforms(transformation);
        List cipherServices = new ArrayList(transforms.size());
        for (Iterator t = transforms.iterator(); t.hasNext(); ) {
            Transform transform = (Transform)t.next();
            cipherServices.add(new ServiceId("Cipher", transform.transform));
        }
        List services = GetInstance.getServices(cipherServices);
        // make sure there is at least one service from a signed provider
        // and that it can use the specified mode and padding
        Iterator t = services.iterator();
        Exception failure = null;
        while (t.hasNext()) {
            Service s = (Service)t.next();
            if (JceSecurity.canUseProvider(s.getProvider()) == false) {
                continue;
            }
            Transform tr = getTransform(s, transforms);
            if (tr == null) {
                // should never happen
                continue;
            }
            int canuse = tr.supportsModePadding(s);
            if (canuse == S_NO) {
                // does not support mode or padding we need, ignore
                continue;
            }
            if (canuse == S_YES) {
                return new Cipher(null, s, t, transformation, transforms);
            } else { // S_MAYBE, try out if it works
                try {
                    CipherSpi spi = (CipherSpi)s.newInstance(null);
                    tr.setModePadding(spi);
                    return new Cipher(spi, s, t, transformation, transforms);
                } catch (Exception e) {
                    failure = e;
                }
            }
        }
        throw new NoSuchAlgorithmException
            ("Cannot find any provider supporting " + transformation, failure);
}

Returns a Cipher object that implements the specified transformation.

This method traverses the list of registered security Providers, starting with the most preferred Provider. A new Cipher object encapsulating the CipherSpi implementation from the first Provider that supports the specified algorithm is returned.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

 public static final Cipher getInstance(String transformation,
    String provider) throws NoSuchProviderException, NoSuchAlgorithmException, NoSuchPaddingException 
{
        if ((provider == null) || (provider.length() == 0)) {
            throw new IllegalArgumentException("Missing provider");
        }
        Provider p = Security.getProvider(provider);
        if (p == null) {
            throw new NoSuchProviderException("No such provider: " +
                                              provider);
        }
        return getInstance(transformation, p);
}

Returns a Cipher object that implements the specified transformation.

A new Cipher object encapsulating the CipherSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

 public static final Cipher getInstance(String transformation,
    Provider provider) throws NoSuchAlgorithmException, NoSuchPaddingException 
{
        if (provider == null) {
            throw new IllegalArgumentException("Missing provider");
        }
        Exception failure = null;
        List transforms = getTransforms(transformation);
        boolean providerChecked = false;
        String paddingError = null;
        for (Iterator t = transforms.iterator(); t.hasNext();) {
            Transform tr = (Transform)t.next();
            Service s = provider.getService("Cipher", tr.transform);
            if (s == null) {
                continue;
            }
            if (providerChecked == false) {
                // for compatibility, first do the lookup and then verify
                // the provider. this makes the difference between a NSAE
                // and a SecurityException if the
                // provider does not support the algorithm.
                Exception ve = JceSecurity.getVerificationResult(provider);
                if (ve != null) {
                    String msg = "JCE cannot authenticate the provider "
                        + provider.getName();
                    throw new SecurityException(msg, ve);
                }
                providerChecked = true;
            }
            if (tr.supportsMode(s) == S_NO) {
                continue;
            }
            if (tr.supportsPadding(s) == S_NO) {
                paddingError = tr.pad;
                continue;
            }
            try {
                CipherSpi spi = (CipherSpi)s.newInstance(null);
                tr.setModePadding(spi);
                Cipher cipher = new Cipher(spi, transformation);
                cipher.provider = s.getProvider();
                cipher.initCryptoPermission();
                return cipher;
            } catch (Exception e) {
                failure = e;
            }
        }
        // throw NoSuchPaddingException if the problem is with padding
        if (failure instanceof NoSuchPaddingException) {
            throw (NoSuchPaddingException)failure;
        }
        if (paddingError != null) {
            throw new NoSuchPaddingException
                ("Padding not supported: " + paddingError);
        }
        throw new NoSuchAlgorithmException
                ("No such algorithm: " + transformation, failure);
}

Returns a Cipher object that implements the specified transformation.

A new Cipher object encapsulating the CipherSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.

 public static final int getMaxAllowedKeyLength(String transformation) throws NoSuchAlgorithmException 
{
        CryptoPermission cp = getConfiguredPermission(transformation);
        return cp.getMaxKeySize();
}

Returns the maximum key length for the specified transformation according to the installed JCE jurisdiction policy files. If JCE unlimited strength jurisdiction policy files are installed, Integer.MAX_VALUE will be returned. For more information on default key size in JCE jurisdiction policy files, please see Appendix E in the Java Cryptography Architecture Reference Guide.

 public static final AlgorithmParameterSpec getMaxAllowedParameterSpec(String transformation) throws NoSuchAlgorithmException 
{
        CryptoPermission cp = getConfiguredPermission(transformation);
        return cp.getAlgorithmParameterSpec();
}

Returns an AlgorithmParameterSpec object which contains the maximum cipher parameter value according to the jurisdiction policy file. If JCE unlimited strength jurisdiction policy files are installed or there is no maximum limit on the parameters for the specified transformation in the policy file, null will be returned.

 public final int getOutputSize(int inputLen) 
{
        if (!initialized && !(this instanceof NullCipher)) {
            throw new IllegalStateException("Cipher not initialized");
        }
        if (inputLen <  0) {
            throw new IllegalArgumentException("Input size must be equal " +
                                               "to or greater than zero");
        }
        chooseFirstProvider();
        return spi.engineGetOutputSize(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.

 public final AlgorithmParameters getParameters() 
{
        chooseFirstProvider();
        return spi.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 a combination of default and random parameter values used by the underlying cipher implementation if this cipher requires algorithm parameters but was not initialized with any.

 public final Provider getProvider() 
{
        chooseFirstProvider();
        return this.provider;
}

Returns the provider of this Cipher object.

 public final  void init(int opmode,
    Key key) throws InvalidKeyException 
{
        init(opmode, key, JceSecurity.RANDOM);
}

Initializes this cipher with a key.

The cipher 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 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 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.

 public final  void init(int opmode,
    Certificate certificate) throws InvalidKeyException 
{
        init(opmode, certificate, JceSecurity.RANDOM);
}

Initializes this cipher with the public key from the given certificate.

The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of opmode.

If the certificate is of type X.509 and has a key usage extension field marked as critical, and the value of the key usage extension field implies that the public key in the certificate and its corresponding private key are not supposed to be used for the operation represented by the value of opmode, an InvalidKeyException is thrown.

If this cipher requires any algorithm parameters that cannot be derived from the public key in the given certificate, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or ramdom 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 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 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.

 public final  void init(int opmode,
    Key key,
    SecureRandom random) throws InvalidKeyException 
{
        initialized = false;
        checkOpmode(opmode);
        if (spi != null) {
            checkCryptoPerm(spi, key);
            spi.engineInit(opmode, key, random);
        } else {
            try {
                chooseProvider(I_KEY, opmode, key, null, null, random);
            } catch (InvalidAlgorithmParameterException e) {
                // should never occur
                throw new InvalidKeyException(e);
            }
        }
        initialized = true;
        this.opmode = opmode;
}

Initializes this cipher with a key and a source of randomness.

The cipher 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 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 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.

 public final  void init(int opmode,
    Key key,
    AlgorithmParameterSpec params) throws InvalidKeyException, InvalidAlgorithmParameterException 
{
        init(opmode, key, params, JceSecurity.RANDOM);
}

Initializes this cipher with a key and a set of algorithm parameters.

The cipher 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 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 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.

 public final  void init(int opmode,
    Key key,
    AlgorithmParameters params) throws InvalidKeyException, InvalidAlgorithmParameterException 
{
        init(opmode, key, params, JceSecurity.RANDOM);
}

Initializes this cipher with a key and a set of algorithm parameters.

The cipher 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 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 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.

 public final  void init(int opmode,
    Certificate certificate,
    SecureRandom random) throws InvalidKeyException 
{
        initialized = false;
        checkOpmode(opmode);
        // Check key usage if the certificate is of
        // type X.509.
        if (certificate instanceof java.security.cert.X509Certificate) {
            // Check whether the cert has a key usage extension
            // marked as a critical extension.
            X509Certificate cert = (X509Certificate)certificate;
            Set critSet = cert.getCriticalExtensionOIDs();
            if (critSet != null && !critSet.isEmpty()
                && critSet.contains(KEY_USAGE_EXTENSION_OID)) {
                boolean[] keyUsageInfo = cert.getKeyUsage();
                // keyUsageInfo[2] is for keyEncipherment;
                // keyUsageInfo[3] is for dataEncipherment.
                if ((keyUsageInfo != null) &&
                    (((opmode == Cipher.ENCRYPT_MODE) &&
                      (keyUsageInfo.length  > 3) &&
                      (keyUsageInfo[3] == false)) ||
                     ((opmode == Cipher.WRAP_MODE) &&
                      (keyUsageInfo.length  > 2) &&
                      (keyUsageInfo[2] == false)))) {
                    throw new InvalidKeyException("Wrong key usage");
                }
            }
        }
        PublicKey publicKey =
            (certificate==null? null:certificate.getPublicKey());
        if (spi != null) {
            checkCryptoPerm(spi, publicKey);
            spi.engineInit(opmode, publicKey, random);
        } else {
            try {
                chooseProvider(I_CERT, opmode, publicKey, null, null, random);
            } catch (InvalidAlgorithmParameterException e) {
                // should never occur
                throw new InvalidKeyException(e);
            }
        }
        initialized = true;
        this.opmode = opmode;
}

Initializes this cipher with the public key from the given certificate and a source of randomness.

The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of opmode.

If the certificate is of type X.509 and has a key usage extension field marked as critical, and the value of the key usage extension field implies that the public key in the certificate and its corresponding private key are not supposed to be used for the operation represented by the value of opmode, an InvalidKeyException is thrown.

If this cipher requires any algorithm parameters that cannot be derived from the public key in the given certificate, 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 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 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.

 public final  void init(int opmode,
    Key key,
    AlgorithmParameterSpec params,
    SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException 
{
        initialized = false;
        checkOpmode(opmode);
        if (spi != null) {
            checkCryptoPerm(spi, key, params);
            spi.engineInit(opmode, key, params, random);
        } else {
            chooseProvider(I_PARAMSPEC, opmode, key, params, null, random);
        }
        initialized = true;
        this.opmode = opmode;
}

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

The cipher 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 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 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.

 public final  void init(int opmode,
    Key key,
    AlgorithmParameters params,
    SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException 
{
        initialized = false;
        checkOpmode(opmode);
        if (spi != null) {
            checkCryptoPerm(spi, key, params);
            spi.engineInit(opmode, key, params, random);
        } else {
            chooseProvider(I_PARAMS, opmode, key, null, params, random);
        }
        initialized = true;
        this.opmode = opmode;
}

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

The cipher 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 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 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.

 public final Key unwrap(byte[] wrappedKey,
    String wrappedKeyAlgorithm,
    int wrappedKeyType) throws InvalidKeyException, NoSuchAlgorithmException 
{
        if (!(this instanceof NullCipher)) {
            if (!initialized) {
                throw new IllegalStateException("Cipher not initialized");
            }
            if (opmode != Cipher.UNWRAP_MODE) {
                throw new IllegalStateException("Cipher not initialized " +
                                                "for unwrapping keys");
            }
        }
        if ((wrappedKeyType != SECRET_KEY) &&
            (wrappedKeyType != PRIVATE_KEY) &&
            (wrappedKeyType != PUBLIC_KEY)) {
            throw new InvalidParameterException("Invalid key type");
        }
        chooseFirstProvider();
        return spi.engineUnwrap(wrappedKey,
                                      wrappedKeyAlgorithm,
                                      wrappedKeyType);
}

Unwrap a previously wrapped key.

 public final byte[] update(byte[] input) 
{
        checkCipherState();
        // Input sanity check
        if (input == null) {
            throw new IllegalArgumentException("Null input buffer");
        }
        chooseFirstProvider();
        if (input.length == 0) {
            return null;
        }
        return spi.engineUpdate(input, 0, input.length);
}

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

The bytes in the input buffer are processed, and the result is stored in a new buffer.

If input has a length of zero, this method returns null.

 public final int update(ByteBuffer input,
    ByteBuffer output) throws ShortBufferException 
{
        checkCipherState();
        if ((input == null) || (output == null)) {
            throw new IllegalArgumentException("Buffers must not be null");
        }
        if (input == output) {
            throw new IllegalArgumentException("Input and output buffers must "
                + "not be the same object, consider using buffer.duplicate()");
        }
        if (output.isReadOnly()) {
            throw new ReadOnlyBufferException();
        }
        chooseFirstProvider();
        return spi.engineUpdate(input, output);
}

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

All input.remaining() bytes starting at input.position() are processed. The result is stored in the output buffer. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. The output buffer's position will have advanced by n, where n is the value returned by this method; the output buffer's limit will not have changed.

If output.remaining() bytes are insufficient 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.

Note: this method should be copy-safe, which means the input and output buffers can reference the same block of memory and no unprocessed input data is overwritten when the result is copied into the output buffer.

 public final byte[] update(byte[] input,
    int inputOffset,
    int inputLen) 
{
        checkCipherState();
        // Input sanity check
        if (input == null || inputOffset <  0
            || inputLen  > (input.length - inputOffset) || inputLen <  0) {
            throw new IllegalArgumentException("Bad arguments");
        }
        chooseFirstProvider();
        if (inputLen == 0) {
            return null;
        }
        return spi.engineUpdate(input, inputOffset, inputLen);
}

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

If inputLen is zero, this method returns null.

 public final int update(byte[] input,
    int inputOffset,
    int inputLen,
    byte[] output) throws ShortBufferException 
{
        checkCipherState();
        // Input sanity check
        if (input == null || inputOffset <  0
            || inputLen  > (input.length - inputOffset) || inputLen <  0) {
            throw new IllegalArgumentException("Bad arguments");
        }
        chooseFirstProvider();
        if (inputLen == 0) {
            return 0;
        }
        return spi.engineUpdate(input, inputOffset, inputLen,
                                      output, 0);
}

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

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.

If inputLen is zero, this method returns a length of zero.

Note: this method should be copy-safe, which means the input and output buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

 public final int update(byte[] input,
    int inputOffset,
    int inputLen,
    byte[] output,
    int outputOffset) throws ShortBufferException 
{
        checkCipherState();
        // Input sanity check
        if (input == null || inputOffset <  0
            || inputLen  > (input.length - inputOffset) || inputLen <  0
            || outputOffset <  0) {
            throw new IllegalArgumentException("Bad arguments");
        }
        chooseFirstProvider();
        if (inputLen == 0) {
            return 0;
        }
        return spi.engineUpdate(input, inputOffset, inputLen,
                                      output, outputOffset);
}

Continues a multiple-part encryption or decryption operation (depending on how this cipher 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. In this case, repeat this call with a larger output buffer. Use getOutputSize to determine how big the output buffer should be.

If inputLen is zero, this method returns a length of zero.

Note: this method should be copy-safe, which means the input and output buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

 public final byte[] wrap(Key key) throws IllegalBlockSizeException, InvalidKeyException 
{
        if (!(this instanceof NullCipher)) {
            if (!initialized) {
                throw new IllegalStateException("Cipher not initialized");
            }
            if (opmode != Cipher.WRAP_MODE) {
                throw new IllegalStateException("Cipher not initialized " +
                                                "for wrapping keys");
            }
        }
        chooseFirstProvider();
        return spi.engineWrap(key);
}

Wrap a key.