File	Doc	Category	Size	Date	Package
MessageDigestSpi.java	API Doc	Java SE 5 API	6024	Fri Aug 26 14:57:14 BST 2005	java.security

MessageDigestSpi

• java.lang.Object

Fields Summary

Constructors Summary

Methods Summary
public java.lang.Object	clone() Returns a clone if the implementation is cloneable. return a clone if the implementation is cloneable. exception CloneNotSupportedException if this is called on an implementation that does not support Cloneable. if (this instanceof Cloneable) { return super.clone(); } else { throw new CloneNotSupportedException(); }
protected abstract byte[]	engineDigest() Completes the hash computation by performing final operations such as padding. Once engineDigest has been called, the engine should be reset (see {@link #engineReset() engineReset}). Resetting is the responsibility of the engine implementor. return the array of bytes for the resulting hash value.
protected int	engineDigest(byte[] buf, int offset, int len) Completes the hash computation by performing final operations such as padding. Once engineDigest has been called, the engine should be reset (see {@link #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. param buf the output buffer in which to store the digest param offset offset to start from in the output buffer param 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. return the length of the digest stored in the output buffer. exception DigestException if an error occurs. since 1.2 byte[] digest = engineDigest(); if (len < digest.length) throw new DigestException("partial digests not returned"); if (buf.length - offset < digest.length) throw new DigestException("insufficient space in the output " + "buffer to store the digest"); System.arraycopy(digest, 0, buf, offset, digest.length); return digest.length;
protected int	engineGetDigestLength() 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. return the digest length in bytes. since 1.2 return 0;
protected abstract void	engineReset() Resets the digest for further use.
protected abstract void	engineUpdate(byte input) Updates the digest using the specified byte. param input the byte to use for the update.
protected abstract void	engineUpdate(byte[] input, int offset, int len) Updates the digest using the specified array of bytes, starting at the specified offset. param input the array of bytes to use for the update. param offset the offset to start from in the array of bytes. param len the number of bytes to use, starting at offset.
protected void	engineUpdate(java.nio.ByteBuffer input) Update the digest using the specified ByteBuffer. The digest is updated using the input.remaining() bytes starting at input.position(). Upon return, the buffer's position will be equal to its limit; its limit will not have changed. param input the ByteBuffer since 1.5 if (input.hasRemaining() == false) { return; } if (input.hasArray()) { byte[] b = input.array(); int ofs = input.arrayOffset(); int pos = input.position(); int lim = input.limit(); engineUpdate(b, ofs + pos, lim - pos); input.position(lim); } else { int len = input.remaining(); byte[] b = new byte[JCAUtil.getTempArraySize(len)]; while (len > 0) { int chunk = Math.min(len, b.length); input.get(b, 0, chunk); engineUpdate(b, 0, chunk); len -= chunk; } }