public abstract class MessageDigest
extends java.lang.Object
A MessageDigest
object starts out initialized. The data is
processed through it using the update
method. At any point reset
can be called
to reset the digest. Once all the data to be updated has been
updated, the digest
method should
be called to complete the hash computation.
The digest
method can be called once for a given number
of updates. After digest
has been called,
the MessageDigest
object is reset to its initialized state.
Modifier and Type | Method and Description |
---|---|
int |
digest(byte[] buf,
int offset,
int len)
Completes the hash computation by performing final operations
such as padding.
|
static MessageDigest |
getInstance(java.lang.String algorithm)
Generates a
MessageDigest object that implements
the specified digest
algorithm. |
void |
reset()
Resets the digest for further use.
|
void |
update(byte[] input,
int offset,
int len)
Updates the digest using the specified array of bytes, starting
at the specified offset.
|
public static MessageDigest getInstance(java.lang.String algorithm) throws NoSuchAlgorithmException
MessageDigest
object that implements
the specified digest
algorithm.algorithm
- the name of the algorithm requested.
See Appendix A in the
Java Cryptography Architecture API Specification & Reference
for information about standard algorithm names.NoSuchAlgorithmException
- if the algorithm is
not available in the caller's environment.public void update(byte[] input, int offset, int len)
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
.public int digest(byte[] buf, int offset, int len) throws DigestException
buf
- output buffer for the computed digestoffset
- offset into the output buffer to begin storing the digestlen
- number of bytes within buf allotted for the digestbuf
DigestException
- if an error occurs.public void reset()
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