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java.lang.Object | +----java.security.MessageDigestSpi
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.
Constructor Summary | |
MessageDigestSpi()
|
Method Summary | |
Object | clone()
|
byte[] | engineDigest()
|
int | engineDigest(byte[] buf,
int offset,
int len)
|
int | engineGetDigestLength()
|
void | engineReset()
|
void | engineUpdate(byte input)
|
void | engineUpdate(byte[] input,
int offset,
int len)
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
public MessageDigestSpi()
Method Detail |
protected int engineGetDigestLength()
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.
protected abstract void engineUpdate(byte input)
input
- the byte to use for the update.
protected abstract void engineUpdate(byte[] input, int offset, int len)
input
- the array of bytes to use for the update.
offset
- the offset to start from in the array of bytes.
len
- the number of bytes to use, starting at
offset
.
protected abstract byte[] engineDigest()
engineDigest
has
been called, the engine should be reset (see engineReset). Resetting is the responsibility of the
engine implementor.protected int engineDigest(byte[] buf, int offset, int len) throws DigestException
engineDigest
has
been called, the engine should be reset (see 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.
buf
- the output buffer in which to store the digest
offset
- offset to start from in the output buffer
len
- number of bytes within buf allotted for the digest.
Both this default implementation and the SUN provider do not
return partial digests. The presence of this parameter is solely
for consistency in our API's. If the value of this parameter is less
than the actual digest length, the method will throw a DigestException.
This parameter is ignored if its value is greater than or equal to
the actual digest length.
protected abstract void engineReset()
public Object clone() throws CloneNotSupportedException
Cloneable
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