| java.lang.Object
 java.security.MessageDigestSpi
All known Subclasses: sun.security.provider.SHA5, sun.security.provider.SHA, com.sun.j2me.crypto.MD2, sun.security.provider.SHA2, sun.security.provider.MD5,
| MessageDigestSpi | | abstract public class MessageDigestSpi (Code) | | This class defines the Service Provider Interface (SPI)
for the MessageDigest class, which provides the functionality
of a message digest algorithm, such as MD5 or SHA. Message digests are
secure one-way hash functions that take arbitrary-sized data and output a
fixed-length hash value.
All the abstract methods in this class must be implemented by a
cryptographic service provider who wishes to supply the implementation
of a particular message digest algorithm.
Implementations are free to implement the Cloneable interface.
author:
Benjamin Renaud
version:
1.11, 02/02/00
See Also: MessageDigest |
| Method Summary | |
| public Object | clone()
Returns a clone if the implementation is cloneable. | | abstract protected byte[] | engineDigest()
Completes the hash computation by performing final
operations such as padding. | | protected int | engineDigest(byte[] buf, int offset, int len)
Completes the hash computation by performing final
operations such as padding. | | protected int | engineGetDigestLength()
Returns the digest length in bytes.
This concrete method has been added to this previously-defined
abstract class. | | abstract protected void | engineReset()
Resets the digest for further use. | | abstract protected void | engineUpdate(byte input)
Updates the digest using the specified byte. | | abstract protected void | engineUpdate(byte[] input, int offset, int len)
Updates the digest using the specified array of bytes,
starting at the specified offset. |
| engineDigest | | abstract protected byte[] engineDigest()(Code) | | Completes the hash computation by performing final
operations such as padding. Once engineDigest has
been called, the engine should be reset (see
MessageDigestSpi.engineReset() engineReset ).
Resetting is the responsibility of the
engine implementor.
the array of bytes for the resulting hash value. |
| engineDigest | | protected int engineDigest(byte[] buf, int offset, int len) throws DigestException(Code) | | Completes the hash computation by performing final
operations such as padding. Once engineDigest has
been called, the engine should be reset (see
MessageDigestSpi.engineReset() engineReset ).
Resetting is the responsibility of the
engine implementor.
This method should be abstract, but we leave it concrete for
binary compatibility. Knowledgeable providers should override this
method.
Parameters:
buf - the output buffer in which to store the digest
Parameters:
offset - offset to start from in the output buffer
Parameters:
len - number of bytes within buf allotted for the digest.Both this default implementation and the SUN provider do notreturn partial digests. The presence of this parameter is solelyfor consistency in our API's. If the value of this parameter is lessthan the actual digest length, the method will throw a DigestException.This parameter is ignored if its value is greater than or equal tothe actual digest length. the length of the digest stored in the output buffer.
exception:
DigestException - if an error occurs.
since:
1.2 |
| engineGetDigestLength | | protected int engineGetDigestLength()(Code) | | Returns the digest length in bytes.
This concrete method has been added to this previously-defined
abstract class. (For backwards compatibility, it cannot be abstract.)
The default behavior is to return 0.
This method may be overridden by a provider to return the digest
length.
the digest length in bytes.
since:
1.2 |
| engineReset | | abstract protected void engineReset()(Code) | | Resets the digest for further use.
|
| engineUpdate | | abstract protected void engineUpdate(byte input)(Code) | | Updates the digest using the specified byte.
Parameters:
input - the byte to use for the update. |
| engineUpdate | | abstract protected void engineUpdate(byte[] input, int offset, int len)(Code) | | Updates the digest using the specified array of bytes,
starting at the specified offset.
Parameters:
input - the array of bytes to use for the update.
Parameters:
offset - the offset to start from in the array of bytes.
Parameters:
len - the number of bytes to use, starting at offset. |
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