JDK8/Java8源码在线阅读
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*
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* accompanied this code).
*
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*
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package javax.crypto;
import java.util.*;
import java.security.*;
import java.security.Provider.Service;
import java.security.spec.AlgorithmParameterSpec;
import java.nio.ByteBuffer;
import sun.security.util.Debug;
import sun.security.jca.*;
import sun.security.jca.GetInstance.Instance;
/**
* This class provides the functionality of a "Message Authentication Code"
* (MAC) algorithm.
*
* <p> A MAC provides a way to check
* the integrity of information transmitted over or stored in an unreliable
* medium, based on a secret key. Typically, message
* authentication codes are used between two parties that share a secret
* key in order to validate information transmitted between these
* parties.
*
* <p> A MAC mechanism that is based on cryptographic hash functions is
* referred to as HMAC. HMAC can be used with any cryptographic hash function,
* e.g., MD5 or SHA-1, in combination with a secret shared key. HMAC is
* specified in RFC 2104.
*
* <p> Every implementation of the Java platform is required to support
* the following standard <code>Mac</code> algorithms:
* <ul>
* <li><tt>HmacMD5</tt></li>
* <li><tt>HmacSHA1</tt></li>
* <li><tt>HmacSHA256</tt></li>
* </ul>
* These algorithms are described in the
* <a href="{@docRoot}/../technotes/guides/security/StandardNames.html#Mac">
* Mac section</a> of the
* Java Cryptography Architecture Standard Algorithm Name Documentation.
* Consult the release documentation for your implementation to see if any
* other algorithms are supported.
*
* @author Jan Luehe
*
* @since 1.4
*/
public class Mac implements Cloneable {
private static final Debug debug =
Debug.getInstance("jca", "Mac");
private static final Debug pdebug =
Debug.getInstance("provider", "Provider");
private static final boolean skipDebug =
Debug.isOn("engine=") && !Debug.isOn("mac");
// The provider
private Provider provider;
// The provider implementation (delegate)
private MacSpi spi;
// The name of the MAC algorithm.
private final String algorithm;
// Has this object been initialized?
private boolean initialized = false;
// 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;
private final Object lock;
/**
* Creates a MAC object.
*
* @param macSpi the delegate
* @param provider the provider
* @param algorithm the algorithm
*/
protected Mac(MacSpi macSpi, Provider provider, String algorithm) {
this.spi = macSpi;
this.provider = provider;
this.algorithm = algorithm;
serviceIterator = null;
lock = null;
}
private Mac(Service s, Iterator<Service> t, String algorithm) {
firstService = s;
serviceIterator = t;
this.algorithm = algorithm;
lock = new Object();
}
/**
* Returns the algorithm name of this <code>Mac</code> object.
*
* <p>This is the same name that was specified in one of the
* <code>getInstance</code> calls that created this
* <code>Mac</code> object.
*
* @return the algorithm name of this <code>Mac</code> object.
*/
public final String getAlgorithm() {
return this.algorithm;
}
/**
* Returns a <code>Mac</code> object that implements the
* specified MAC algorithm.
*
* <p> This method traverses the list of registered security Providers,
* starting with the most preferred Provider.
* A new Mac object encapsulating the
* MacSpi 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.
*
* @param algorithm the standard name of the requested MAC algorithm.
* See the Mac section in the <a href=
* "{@docRoot}/../technotes/guides/security/StandardNames.html#Mac">
* Java Cryptography Architecture Standard Algorithm Name Documentation</a>
* for information about standard algorithm names.
*
* @return the new <code>Mac</code> object.
*
* @exception NoSuchAlgorithmException if no Provider supports a
* MacSpi implementation for the
* specified algorithm.
*
* @see java.security.Provider
*/
public static final Mac getInstance(String algorithm)
throws NoSuchAlgorithmException {
List<Service> services = GetInstance.getServices("Mac", algorithm);
// make sure there is at least one service from a signed provider
Iterator<Service> t = services.iterator();
while (t.hasNext()) {
Service s = t.next();
if (JceSecurity.canUseProvider(s.getProvider()) == false) {
continue;
}
return new Mac(s, t, algorithm);
}
throw new NoSuchAlgorithmException
("Algorithm " + algorithm + " not available");
}
/**
* Returns a <code>Mac</code> object that implements the
* specified MAC algorithm.
*
* <p> A new Mac object encapsulating the
* MacSpi implementation from the specified provider
* is returned. The specified provider must be registered
* in the security provider list.
*
* <p> Note that the list of registered providers may be retrieved via
* the {@link Security#getProviders() Security.getProviders()} method.
*
* @param algorithm the standard name of the requested MAC algorithm.
* See the Mac section in the <a href=
* "{@docRoot}/../technotes/guides/security/StandardNames.html#Mac">
* Java Cryptography Architecture Standard Algorithm Name Documentation</a>
* for information about standard algorithm names.
*
* @param provider the name of the provider.
*
* @return the new <code>Mac</code> object.
*
* @exception NoSuchAlgorithmException if a MacSpi
* implementation for the specified algorithm is not
* available from the specified provider.
*
* @exception NoSuchProviderException if the specified provider is not
* registered in the security provider list.
*
* @exception IllegalArgumentException if the <code>provider</code>
* is null or empty.
*
* @see java.security.Provider
*/
public static final Mac getInstance(String algorithm, String provider)
throws NoSuchAlgorithmException, NoSuchProviderException {
Instance instance = JceSecurity.getInstance
("Mac", MacSpi.class, algorithm, provider);
return new Mac((MacSpi)instance.impl, instance.provider, algorithm);
}
/**
* Returns a <code>Mac</code> object that implements the
* specified MAC algorithm.
*
* <p> A new Mac object encapsulating the
* MacSpi implementation from the specified Provider
* object is returned. Note that the specified Provider object
* does not have to be registered in the provider list.
*
* @param algorithm the standard name of the requested MAC algorithm.
* See the Mac section in the <a href=
* "{@docRoot}/../technotes/guides/security/StandardNames.html#Mac">
* Java Cryptography Architecture Standard Algorithm Name Documentation</a>
* for information about standard algorithm names.
*
* @param provider the provider.
*
* @return the new <code>Mac</code> object.
*
* @exception NoSuchAlgorithmException if a MacSpi
* implementation for the specified algorithm is not available
* from the specified Provider object.
*
* @exception IllegalArgumentException if the <code>provider</code>
* is null.
*
* @see java.security.Provider
*/
public static final Mac getInstance(String algorithm, Provider provider)
throws NoSuchAlgorithmException {
Instance instance = JceSecurity.getInstance
("Mac", MacSpi.class, algorithm, provider);
return new Mac((MacSpi)instance.impl, instance.provider, algorithm);
}
// max number of debug warnings to print from chooseFirstProvider()
private static int warnCount = 10;
/**
* Choose the Spi from the first provider available. Used if
* delayed provider selection is not possible because init()
* is not the first method called.
*/
void chooseFirstProvider() {
if ((spi != null) || (serviceIterator == null)) {
return;
}
synchronized (lock) {
if (spi != null) {
return;
}
if (debug != null) {
int w = --warnCount;
if (w >= 0) {
debug.println("Mac.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;
if (firstService != null) {
s = firstService;
firstService = null;
} else {
s = serviceIterator.next();
}
if (JceSecurity.canUseProvider(s.getProvider()) == false) {
continue;
}
try {
Object obj = s.newInstance(null);
if (obj instanceof MacSpi == false) {
continue;
}
spi = (MacSpi)obj;
provider = s.getProvider();
// not needed any more
firstService = null;
serviceIterator = null;
return;
} catch (NoSuchAlgorithmException e) {
lastException = e;
}
}
ProviderException e = new ProviderException
("Could not construct MacSpi instance");
if (lastException != null) {
e.initCause(lastException);
}
throw e;
}
}
private void chooseProvider(Key key, AlgorithmParameterSpec params)
throws InvalidKeyException, InvalidAlgorithmParameterException {
synchronized (lock) {
if (spi != null) {
spi.engineInit(key, params);
return;
}
Exception lastException = null;
while ((firstService != null) || serviceIterator.hasNext()) {
Service s;
if (firstService != null) {
s = firstService;
firstService = null;
} else {
s = serviceIterator.next();
}
// if provider says it does not support this key, ignore it
if (s.supportsParameter(key) == false) {
continue;
}
if (JceSecurity.canUseProvider(s.getProvider()) == false) {
continue;
}
try {
MacSpi spi = (MacSpi)s.newInstance(null);
spi.engineInit(key, params);
provider = s.getProvider();
this.spi = spi;
firstService = null;
serviceIterator = null;
return;
} catch (Exception e) {
// NoSuchAlgorithmException from newInstance()
// InvalidKeyException from init()
// RuntimeException (ProviderException) from init()
if (lastException == null) {
lastException = e;
}
}
}
// no working provider found, fail
if (lastException instanceof InvalidKeyException) {
throw (InvalidKeyException)lastException;
}
if (lastException instanceof InvalidAlgorithmParameterException) {
throw (InvalidAlgorithmParameterException)lastException;
}
if (lastException instanceof RuntimeException) {
throw (RuntimeException)lastException;
}
String kName = (key != null) ? key.getClass().getName() : "(null)";
throw new InvalidKeyException
("No installed provider supports this key: "
+ kName, lastException);
}
}
/**
* Returns the provider of this <code>Mac</code> object.
*
* @return the provider of this <code>Mac</code> object.
*/
public final Provider getProvider() {
chooseFirstProvider();
return this.provider;
}
/**
* Returns the length of the MAC in bytes.
*
* @return the MAC length in bytes.
*/
public final int getMacLength() {
chooseFirstProvider();
return spi.engineGetMacLength();
}
/**
* Initializes this <code>Mac</code> object with the given key.
*
* @param key the key.
*
* @exception InvalidKeyException if the given key is inappropriate for
* initializing this MAC.
*/
public final void init(Key key) throws InvalidKeyException {
try {
if (spi != null) {
spi.engineInit(key, null);
} else {
chooseProvider(key, null);
}
} catch (InvalidAlgorithmParameterException e) {
throw new InvalidKeyException("init() failed", e);
}
initialized = true;
if (!skipDebug && pdebug != null) {
pdebug.println("Mac." + algorithm + " algorithm from: " +
this.provider.getName());
}
}
/**
* Initializes this <code>Mac</code> object with the given key and
* algorithm parameters.
*
* @param key the key.
* @param params the algorithm parameters.
*
* @exception InvalidKeyException if the given key is inappropriate for
* initializing this MAC.
* @exception InvalidAlgorithmParameterException if the given algorithm
* parameters are inappropriate for this MAC.
*/
public final void init(Key key, AlgorithmParameterSpec params)
throws InvalidKeyException, InvalidAlgorithmParameterException {
if (spi != null) {
spi.engineInit(key, params);
} else {
chooseProvider(key, params);
}
initialized = true;
if (!skipDebug && pdebug != null) {
pdebug.println("Mac." + algorithm + " algorithm from: " +
this.provider.getName());
}
}
/**
* Processes the given byte.
*
* @param input the input byte to be processed.
*
* @exception IllegalStateException if this <code>Mac</code> has not been
* initialized.
*/
public final void update(byte input) throws IllegalStateException {
chooseFirstProvider();
if (initialized == false) {
throw new IllegalStateException("MAC not initialized");
}
spi.engineUpdate(input);
}
/**
* Processes the given array of bytes.
*
* @param input the array of bytes to be processed.
*
* @exception IllegalStateException if this <code>Mac</code> has not been
* initialized.
*/
public final void update(byte[] input) throws IllegalStateException {
chooseFirstProvider();
if (initialized == false) {
throw new IllegalStateException("MAC not initialized");
}
if (input != null) {
spi.engineUpdate(input, 0, input.length);
}
}
/**
* Processes the first <code>len</code> bytes in <code>input</code>,
* starting at <code>offset</code> inclusive.
*
* @param input the input buffer.
* @param offset the offset in <code>input</code> where the input starts.
* @param len the number of bytes to process.
*
* @exception IllegalStateException if this <code>Mac</code> has not been
* initialized.
*/
public final void update(byte[] input, int offset, int len)
throws IllegalStateException {
chooseFirstProvider();
if (initialized == false) {
throw new IllegalStateException("MAC not initialized");
}
if (input != null) {
if ((offset < 0) || (len > (input.length - offset)) || (len < 0))
throw new IllegalArgumentException("Bad arguments");
spi.engineUpdate(input, offset, len);
}
}
/**
* Processes <code>input.remaining()</code> bytes in the ByteBuffer
* <code>input</code>, starting at <code>input.position()</code>.
* Upon return, the buffer's position will be equal to its limit;
* its limit will not have changed.
*
* @param input the ByteBuffer
*
* @exception IllegalStateException if this <code>Mac</code> has not been
* initialized.
* @since 1.5
*/
public final void update(ByteBuffer input) {
chooseFirstProvider();
if (initialized == false) {
throw new IllegalStateException("MAC not initialized");
}
if (input == null) {
throw new IllegalArgumentException("Buffer must not be null");
}
spi.engineUpdate(input);
}
/**
* Finishes the MAC operation.
*
* <p>A call to this method resets this <code>Mac</code> object to the
* state it was in when previously initialized via a call to
* <code>init(Key)</code> or
* <code>init(Key, AlgorithmParameterSpec)</code>.
* That is, the object is reset and available to generate another MAC from
* the same key, if desired, via new calls to <code>update</code> and
* <code>doFinal</code>.
* (In order to reuse this <code>Mac</code> object with a different key,
* it must be reinitialized via a call to <code>init(Key)</code> or
* <code>init(Key, AlgorithmParameterSpec)</code>.
*
* @return the MAC result.
*
* @exception IllegalStateException if this <code>Mac</code> has not been
* initialized.
*/
public final byte[] doFinal() throws IllegalStateException {
chooseFirstProvider();
if (initialized == false) {
throw new IllegalStateException("MAC not initialized");
}
byte[] mac = spi.engineDoFinal();
spi.engineReset();
return mac;
}
/**
* Finishes the MAC operation.
*
* <p>A call to this method resets this <code>Mac</code> object to the
* state it was in when previously initialized via a call to
* <code>init(Key)</code> or
* <code>init(Key, AlgorithmParameterSpec)</code>.
* That is, the object is reset and available to generate another MAC from
* the same key, if desired, via new calls to <code>update</code> and
* <code>doFinal</code>.
* (In order to reuse this <code>Mac</code> object with a different key,
* it must be reinitialized via a call to <code>init(Key)</code> or
* <code>init(Key, AlgorithmParameterSpec)</code>.
*
* <p>The MAC result is stored in <code>output</code>, starting at
* <code>outOffset</code> inclusive.
*
* @param output the buffer where the MAC result is stored
* @param outOffset the offset in <code>output</code> where the MAC is
* stored
*
* @exception ShortBufferException if the given output buffer is too small
* to hold the result
* @exception IllegalStateException if this <code>Mac</code> has not been
* initialized.
*/
public final void doFinal(byte[] output, int outOffset)
throws ShortBufferException, IllegalStateException
{
chooseFirstProvider();
if (initialized == false) {
throw new IllegalStateException("MAC not initialized");
}
int macLen = getMacLength();
if (output == null || output.length-outOffset < macLen) {
throw new ShortBufferException
("Cannot store MAC in output buffer");
}
byte[] mac = doFinal();
System.arraycopy(mac, 0, output, outOffset, macLen);
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