java.security
Class MessageDigest

java.lang.Object
  |
  +--java.security.MessageDigestSpi
        |
        +--java.security.MessageDigest
Direct Known Subclasses:
java.security.MessageDigest.Delegate

public abstract class MessageDigest
extends MessageDigestSpi

Untamed:


Field Summary
private  String algorithm
           
private static int IN_PROGRESS
           
private static int INITIAL
           
private  Provider provider
           
private  int state
           
 
Constructor Summary
protected MessageDigest(String algorithm)
          Creates a message digest with the specified algorithm name.
 
Method Summary
 Object clone()
          Suppressed: Returns a clone if the implementation is cloneable.
 byte[] digest()
          Enabled: Completes the hash computation by performing final operations such as padding.
 byte[] digest(byte[] input)
          Enabled: Performs a final update on the digest using the specified array of bytes, then completes the digest computation.
 int digest(byte[] buf, int offset, int len)
          Enabled: Completes the hash computation by performing final operations such as padding.
 String getAlgorithm()
          Enabled: Returns a string that identifies the algorithm, independent of implementation details.
 int getDigestLength()
          Enabled: Returns the length of the digest in bytes, or 0 if this operation is not supported by the provider and the implementation is not cloneable.
static MessageDigest getInstance(String algorithm)
          Enabled: Generates a MessageDigest object that implements the specified digest algorithm.
static MessageDigest getInstance(String algorithm, Provider provider)
          Enabled: Generates a MessageDigest object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider.
static MessageDigest getInstance(String algorithm, String provider)
          Enabled: Generates a MessageDigest object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider.
 Provider getProvider()
          Enabled: Returns the provider of this message digest object.
static boolean isEqual(byte[] digesta, byte[] digestb)
          Enabled: Compares two digests for equality.
 void reset()
          Enabled: Resets the digest for further use.
 String toString()
          Suppressed: Returns a string representation of this message digest object.
 void update(byte input)
          Enabled: Updates the digest using the specified byte.
 void update(byte[] input)
          Enabled: Updates the digest using the specified array of bytes.
 void update(byte[] input, int offset, int len)
          Enabled: Updates the digest using the specified array of bytes, starting at the specified offset.
 
Methods inherited from class java.security.MessageDigestSpi
engineDigest, engineDigest, engineGetDigestLength, engineReset, engineUpdate, engineUpdate
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

algorithm

private String algorithm

INITIAL

private static final int INITIAL

IN_PROGRESS

private static final int IN_PROGRESS

state

private int state

provider

private Provider provider
Constructor Detail

MessageDigest

protected MessageDigest(String algorithm)
Creates a message digest with the specified algorithm name.

Parameters:
algorithm - the standard name of the digest algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
Method Detail

getInstance

public static MessageDigest getInstance(String algorithm)
                                 throws NoSuchAlgorithmException
Enabled: Generates a MessageDigest object that implements the specified digest algorithm. If the default provider package provides an implementation of the requested digest algorithm, an instance of MessageDigest containing that implementation is returned. If the algorithm is not available in the default package, other packages are searched.

Parameters:
algorithm - the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
Returns:
a Message Digest object implementing the specified algorithm.
NoSuchAlgorithmException

getInstance

public static MessageDigest getInstance(String algorithm,
                                        String provider)
                                 throws NoSuchAlgorithmException,
                                        NoSuchProviderException
Enabled: Generates a MessageDigest object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider.

Parameters:
algorithm - the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
provider - the name of the provider.
Returns:
a Message Digest object implementing the specified algorithm.
NoSuchAlgorithmException
NoSuchProviderException
See Also:
Provider

getInstance

public static MessageDigest getInstance(String algorithm,
                                        Provider provider)
                                 throws NoSuchAlgorithmException
Enabled: Generates a MessageDigest object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider. Note: the provider doesn't have to be registered.

Parameters:
algorithm - the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
provider - the provider.
Returns:
a Message Digest object implementing the specified algorithm.
NoSuchAlgorithmException
Since:
1.4
See Also:
Provider

getProvider

public final Provider getProvider()
Enabled: Returns the provider of this message digest object.

Returns:
the provider of this message digest object

update

public void update(byte input)
Enabled: Updates the digest using the specified byte.

Parameters:
input - the byte with which to update the digest.

update

public void update(byte[] input,
                   int offset,
                   int len)
Enabled: Updates the digest using the specified array of bytes, starting at the specified offset.

Parameters:
input - the array of bytes.
offset - the offset to start from in the array of bytes.
len - the number of bytes to use, starting at offset.

update

public void update(byte[] input)
Enabled: Updates the digest using the specified array of bytes.

Parameters:
input - the array of bytes.

digest

public byte[] digest()
Enabled: Completes the hash computation by performing final operations such as padding. The digest is reset after this call is made.

Returns:
the array of bytes for the resulting hash value.

digest

public int digest(byte[] buf,
                  int offset,
                  int len)
           throws DigestException
Enabled: Completes the hash computation by performing final operations such as padding. The digest is reset after this call is made.

Parameters:
buf - output buffer for the computed digest
offset - offset into the output buffer to begin storing the digest
len - number of bytes within buf allotted for the digest
Returns:
the number of bytes placed into buf
DigestException

digest

public byte[] digest(byte[] input)
Enabled: Performs a final update on the digest using the specified array of bytes, then completes the digest computation. That is, this method first calls update(input), passing the input array to the update method, then calls digest().

Parameters:
input - the input to be updated before the digest is completed.
Returns:
the array of bytes for the resulting hash value.

toString

public String toString()
Suppressed: Returns a string representation of this message digest object.

Overrides:
toString in class Object
Returns:
a string representation of the object.

isEqual

public static boolean isEqual(byte[] digesta,
                              byte[] digestb)
Enabled: Compares two digests for equality. Does a simple byte compare.

Parameters:
digesta - one of the digests to compare.
digestb - the other digest to compare.
Returns:
true if the digests are equal, false otherwise.

reset

public void reset()
Enabled: Resets the digest for further use.


getAlgorithm

public final String getAlgorithm()
Enabled: Returns a string that identifies the algorithm, independent of implementation details. The name should be a standard Java Security name (such as "SHA", "MD5", and so on). See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.

Returns:
the name of the algorithm

getDigestLength

public final int getDigestLength()
Enabled: Returns the length of the digest in bytes, or 0 if this operation is not supported by the provider and the implementation is not cloneable.

Returns:
the digest length in bytes, or 0 if this operation is not supported by the provider and the implementation is not cloneable.
Since:
1.2

clone

public Object clone()
             throws CloneNotSupportedException
Suppressed: Returns a clone if the implementation is cloneable.

Overrides:
clone in class MessageDigestSpi
Returns:
a clone if the implementation is cloneable.
CloneNotSupportedException


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