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package javax.crypto;

import java.util.*;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ConcurrentMap;

import java.util.regex.*;

import java.security.*;

import java.security.Provider.Service;

import java.security.spec.AlgorithmParameterSpec;

import java.security.spec.InvalidParameterSpecException;

import java.security.cert.Certificate;

import java.security.cert.X509Certificate;

import javax.crypto.spec.*;

import java.nio.ByteBuffer;

import java.nio.ReadOnlyBufferException;

import sun.security.util.Debug;

import sun.security.jca.*;

/**

 * This class provides the functionality of a cryptographic cipher for

 * encryption and decryption. It forms the core of the Java Cryptographic

 * Extension (JCE) framework.

 *

 * <p>In order to create a Cipher object, the application calls the

 * Cipher's {@code getInstance} method, and passes the name of the

 * requested <i>transformation</i> to it. Optionally, the name of a provider

 * may be specified.

 *

 * <p>A <i>transformation</i> 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., <i>AES</i>), and may be followed by a feedback mode and

 * padding scheme.

 *

 * <p> A transformation is of the form:

 *

 * <ul>

 * <li>"<i>algorithm/mode/padding</i>" or

 *

 * <li>"<i>algorithm</i>"

 * </ul>

 *

 * <P> (in the latter case,

 * provider-specific default values for the mode and padding scheme are used).

 * For example, the following is a valid transformation:

 *

 * <pre>

 *     Cipher c = Cipher.getInstance("<i>AES/CBC/PKCS5Padding</i>");

 * </pre>

 *

 * Using modes such as {@code CFB} and {@code OFB}, block

 * ciphers can encrypt data in units smaller than the cipher's actual

 * block size.  When requesting such a mode, you 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 "{@code AES/CFB8/NoPadding}" and

 * "{@code AES/OFB32/PKCS5Padding}" transformations. If no such

 * number is specified, a provider-specific default is used.

 * (See the

 * {@extLink security_guide_jdk_providers JDK Providers Documentation}

 * for the JDK Providers default values.)

 * Thus, block ciphers can be turned into byte-oriented stream ciphers by

 * using an 8 bit mode such as CFB8 or OFB8.

 * <p>

 * Modes such as Authenticated Encryption with Associated Data (AEAD)

 * provide authenticity assurances for both confidential data and

 * Additional Associated Data (AAD) that is not encrypted.  (Please see

 * <a href="http://www.ietf.org/rfc/rfc5116.txt"> RFC 5116 </a> for more

 * information on AEAD and AAD algorithms such as GCM/CCM.) Both

 * confidential and AAD data can be used when calculating the

 * authentication tag (similar to a {@link Mac}).  This tag is appended

 * to the ciphertext during encryption, and is verified on decryption.

 * <p>

 * AEAD modes such as GCM/CCM perform all AAD authenticity calculations

 * before starting the ciphertext authenticity calculations.  To avoid

 * implementations having to internally buffer ciphertext, all AAD data

 * must be supplied to GCM/CCM implementations (via the {@code updateAAD}

 * methods) <b>before</b> the ciphertext is processed (via

 * the {@code update} and {@code doFinal} methods).

 * <p>

 * Note that GCM mode has a uniqueness requirement on IVs used in

 * encryption with a given key. When IVs are repeated for GCM

 * encryption, such usages are subject to forgery attacks. Thus, after

 * each encryption operation using GCM mode, callers should re-initialize

 * the cipher objects with GCM parameters which has a different IV value.

 * <pre>

 *     GCMParameterSpec s = ...;

 *     cipher.init(..., s);

 *

 *     // If the GCM parameters were generated by the provider, it can

 *     // be retrieved by:

 *     // cipher.getParameters().getParameterSpec(GCMParameterSpec.class);

 *

 *     cipher.updateAAD(...);  // AAD

 *     cipher.update(...);     // Multi-part update

 *     cipher.doFinal(...);    // conclusion of operation

 *

 *     // Use a different IV value for every encryption

 *     byte[] newIv = ...;

 *     s = new GCMParameterSpec(s.getTLen(), newIv);

 *     cipher.init(..., s);

 *     ...

 *

 * </pre>

 * Every implementation of the Java platform is required to support

 * the following standard {@code Cipher} transformations with the keysizes

 * in parentheses:

 * <ul>

 * <li>{@code AES/CBC/NoPadding} (128)</li>

 * <li>{@code AES/CBC/PKCS5Padding} (128)</li>

 * <li>{@code AES/ECB/NoPadding} (128)</li>

 * <li>{@code AES/ECB/PKCS5Padding} (128)</li>

 * <li>{@code AES/GCM/NoPadding} (128)</li>

 * <li>{@code DES/CBC/NoPadding} (56)</li>

 * <li>{@code DES/CBC/PKCS5Padding} (56)</li>

 * <li>{@code DES/ECB/NoPadding} (56)</li>

 * <li>{@code DES/ECB/PKCS5Padding} (56)</li>

 * <li>{@code DESede/CBC/NoPadding} (168)</li>

 * <li>{@code DESede/CBC/PKCS5Padding} (168)</li>

 * <li>{@code DESede/ECB/NoPadding} (168)</li>

 * <li>{@code DESede/ECB/PKCS5Padding} (168)</li>

 * <li>{@code RSA/ECB/PKCS1Padding} (1024, 2048)</li>

 * <li>{@code RSA/ECB/OAEPWithSHA-1AndMGF1Padding} (1024, 2048)</li>

 * <li>{@code RSA/ECB/OAEPWithSHA-256AndMGF1Padding} (1024, 2048)</li>

 * </ul>

 * These transformations are described in the

 * <a href="{@docRoot}/../specs/security/standard-names.html#cipher-algorithm-names">

 * Cipher section</a> of the

 * Java Security Standard Algorithm Names Specification.

 * Consult the release documentation for your implementation to see if any

 * other transformations are supported.

 *

 * @author Jan Luehe

 * @see KeyGenerator

 * @see SecretKey

 * @since 1.4

 */

public class Cipher {

    private static final Debug debug =

                        Debug.getInstance("jca", "Cipher");

    private static final Debug pdebug =

                        Debug.getInstance("provider", "Provider");

    private static final boolean skipDebug =

        Debug.isOn("engine=") && !Debug.isOn("cipher");

    /**

     * Constant used to initialize cipher to encryption mode.

     */

    public static final int ENCRYPT_MODE = 1;

    /**

     * Constant used to initialize cipher to decryption mode.

     */

    public static final int DECRYPT_MODE = 2;

    /**

     * Constant used to initialize cipher to key-wrapping mode.

     */

    public static final int WRAP_MODE = 3;

    /**

     * Constant used to initialize cipher to key-unwrapping mode.

     */

    public static final int UNWRAP_MODE = 4;

    /**

     * Constant used to indicate the to-be-unwrapped key is a "public key".

     */

    public static final int PUBLIC_KEY = 1;

    /**

     * Constant used to indicate the to-be-unwrapped key is a "private key".

     */

    public static final int PRIVATE_KEY = 2;

    /**

     * Constant used to indicate the to-be-unwrapped key is a "secret key".

     */

    public static final int SECRET_KEY = 3;

    // The provider

    private Provider provider;

    // The provider implementation (delegate)

    private CipherSpi spi;

    // The transformation

    private String transformation;

    // Crypto permission representing the maximum allowable cryptographic

    // strength that this Cipher object can be used for. (The cryptographic

    // strength is a function of the keysize and algorithm parameters encoded

    // in the crypto permission.)

    private CryptoPermission cryptoPerm;

    // The exemption mechanism that needs to be enforced

    private ExemptionMechanism exmech;

    // Flag which indicates whether or not this cipher has been initialized

    private boolean initialized = false;

    // The operation mode - store the operation mode after the

    // cipher has been initialized.

    private int opmode = 0;

    // The OID for the KeyUsage extension in an X.509 v3 certificate

    private static final String KEY_USAGE_EXTENSION_OID = "2.5.29.15";

    // next SPI  to try in provider selection

    // null once provider is selected

    private CipherSpi firstSpi;

    // next service to try in provider selection

    // null once provider is selected

    private Service firstService;

    // remaining services to try in provider selection

    // null once provider is selected

    private Iterator<Service> serviceIterator;

    // list of transform Strings to lookup in the provider

    private List<Transform> transforms;

    private final Object lock;

    /**

     * Creates a Cipher object.

     *

     * @param cipherSpi the delegate

     * @param provider the provider

     * @param transformation the transformation

     */

    protected Cipher(CipherSpi cipherSpi,

                     Provider provider,

                     String transformation) {

        // See bug 4341369 & 4334690 for more info.

        // If the caller is trusted, then okay.

        // Otherwise throw a NullPointerException.

        if (!JceSecurityManager.INSTANCE.isCallerTrusted(provider)) {

            throw new NullPointerException();

        }

        this.spi = cipherSpi;

        this.provider = provider;

        this.transformation = transformation;

        this.cryptoPerm = CryptoAllPermission.INSTANCE;

        this.lock = null;

    }

    /**

     * Creates a Cipher object. Called internally and by NullCipher.

     *

     * @param cipherSpi the delegate

     * @param transformation the transformation

     */

    Cipher(CipherSpi cipherSpi, String transformation) {

        this.spi = cipherSpi;

        this.transformation = transformation;

        this.cryptoPerm = CryptoAllPermission.INSTANCE;

        this.lock = null;

    }

    private Cipher(CipherSpi firstSpi, Service firstService,

            Iterator<Service> serviceIterator, String transformation,

            List<Transform> transforms) {

        this.firstSpi = firstSpi;

        this.firstService = firstService;

        this.serviceIterator = serviceIterator;

        this.transforms = transforms;

        this.transformation = transformation;

        this.lock = new Object();

    }

    private static String[] tokenizeTransformation(String transformation)

            throws NoSuchAlgorithmException {

        if (transformation == null) {

            throw new NoSuchAlgorithmException("No transformation given");

        }

        /*

         * array containing the components of a Cipher transformation:

         *

         * index 0: algorithm component (e.g., AES)

         * index 1: feedback component (e.g., CFB)

         * index 2: padding component (e.g., PKCS5Padding)

         */

        String[] parts = new String[3];

        int count = 0;

        StringTokenizer parser = new StringTokenizer(transformation, "/");

        try {

            while (parser.hasMoreTokens() && count < 3) {

                parts[count++] = parser.nextToken().trim();

            }

                throw new NoSuchAlgorithmException("Invalid transformation"

                                               + " format:" +

                                               transformation);

            }

        } catch (NoSuchElementException e) {

            throw new NoSuchAlgorithmException("Invalid transformation " +

                                           "format:" + transformation);

        }

        if ((parts[0] == null) || (parts[0].length() == 0)) {

            throw new NoSuchAlgorithmException("Invalid transformation:" +

                                   "algorithm not specified-"

                                   + transformation);

        }

        return parts;

    }

    // Provider attribute name for supported chaining mode

    private static final String ATTR_MODE = "SupportedModes";

    // Provider attribute name for supported padding names

    private static final String ATTR_PAD  = "SupportedPaddings";

    // constants indicating whether the provider supports

    // a given mode or padding

    private static final int S_NO    = 0;       // does not support

    private static final int S_MAYBE = 1;       // unable to determine

    private static final int S_YES   = 2;       // does support

    /**

     * Nested class to deal with modes and paddings.

     */

    private static class Transform {

        // transform string to lookup in the provider

        final String transform;

        // the mode/padding suffix in upper case. for example, if the algorithm

        // to lookup is "AES/CBC/PKCS5Padding" suffix is "/CBC/PKCS5PADDING"

        // if lookup is "AES", suffix is the empty string

        // needed because aliases prevent straight transform.equals()

        final String suffix;

        // value to pass to setMode() or null if no such call required

        final String mode;

        // value to pass to setPadding() or null if no such call required

        final String pad;

        Transform(String alg, String suffix, String mode, String pad) {

            this.transform = alg + suffix;

            this.suffix = suffix.toUpperCase(Locale.ENGLISH);

            this.mode = mode;

            this.pad = pad;

        }

        // set mode and padding for the given SPI

        void setModePadding(CipherSpi spi) throws NoSuchAlgorithmException,

                NoSuchPaddingException {

            if (mode != null) {

                spi.engineSetMode(mode);

            }

            if (pad != null) {

                spi.engineSetPadding(pad);

            }

        }

        // check whether the given services supports the mode and

        // padding described by this Transform

        int supportsModePadding(Service s) {

            int smode = supportsMode(s);

            if (smode == S_NO) {

                return smode;

            }

            int spad = supportsPadding(s);

            // our constants are defined so that Math.min() is a tri-valued AND

            return Math.min(smode, spad);

        }

        // separate methods for mode and padding

        // called directly by Cipher only to throw the correct exception

        int supportsMode(Service s) {

            return supports(s, ATTR_MODE, mode);

        }

        int supportsPadding(Service s) {

            return supports(s, ATTR_PAD, pad);

        }

        private static int supports(Service s, String attrName, String value) {

            if (value == null) {

                return S_YES;

            }

            String regexp = s.getAttribute(attrName);

            if (regexp == null) {

                return S_MAYBE;

            }

            return matches(regexp, value) ? S_YES : S_NO;

        }

        // ConcurrentMap<String,Pattern> for previously compiled patterns

        private static final ConcurrentMap<String, Pattern> patternCache =

            new ConcurrentHashMap<String, Pattern>();

        private static boolean matches(String regexp, String str) {

            Pattern pattern = patternCache.get(regexp);

            if (pattern == null) {

                pattern = Pattern.compile(regexp);

                patternCache.putIfAbsent(regexp, pattern);

            }

            return pattern.matcher(str.toUpperCase(Locale.ENGLISH)).matches();

        }

    }

    private static List<Transform> getTransforms(String transformation)

            throws NoSuchAlgorithmException {

        String[] parts = tokenizeTransformation(transformation);

        String alg = parts[0];

        String mode = parts[1];

        String pad = parts[2];

        if ((mode != null) && (mode.length() == 0)) {

            mode = null;

        }

        if ((pad != null) && (pad.length() == 0)) {

            pad = null;

        }

        if ((mode == null) && (pad == null)) {

            // AES

            Transform tr = new Transform(alg, "", null, null);

            return Collections.singletonList(tr);

        } else { // if ((mode != null) && (pad != null)) {

            // AES/CBC/PKCS5Padding

            List<Transform> list = new ArrayList<>(4);

            list.add(new Transform(alg, "/" + mode + "/" + pad, null, null));

            list.add(new Transform(alg, "/" + mode, null, pad));

            list.add(new Transform(alg, "//" + pad, mode, null));

            list.add(new Transform(alg, "", mode, pad));

            return list;

        }

    }

    // get the transform matching the specified service

    private static Transform getTransform(Service s,

                                          List<Transform> transforms) {

        String alg = s.getAlgorithm().toUpperCase(Locale.ENGLISH);

        for (Transform tr : transforms) {

            if (alg.endsWith(tr.suffix)) {

                return tr;

            }

        }

        return null;

    }

    /**

     * Returns a {@code Cipher} object that implements the specified

     * transformation.

     *

     * <p> 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.

     *

     * <p> Note that the list of registered providers may be retrieved via

     * the {@link Security#getProviders() Security.getProviders()} method.

     *

     * @implNote

     * The JDK Reference Implementation additionally uses the

     * {@code jdk.security.provider.preferred}

     * {@link Security#getProperty(String) Security} property to determine

     * the preferred provider order for the specified algorithm. This

     * may be different than the order of providers returned by

     * {@link Security#getProviders() Security.getProviders()}.

     *

     * @param transformation the name of the transformation, e.g.,

     * <i>AES/CBC/PKCS5Padding</i>.

     * See the Cipher section in the <a href=

     *   "{@docRoot}/../specs/security/standard-names.html#cipher-algorithm-names">

     * Java Security Standard Algorithm Names Specification</a>

     * for information about standard transformation names.

     *

     * @return a cipher that implements the requested transformation

     *

     * @throws NoSuchAlgorithmException if {@code transformation}

     *         is {@code null}, empty, in an invalid format,

     *         or if no {@code Provider} supports a {@code CipherSpi}

     *         implementation for the specified algorithm

     *

     * @throws NoSuchPaddingException if {@code transformation}

     *         contains a padding scheme that is not available