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:

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

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.

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