hash.java

JAVA的加密源程序

/*
Christoforos Pirillos @ Villanova University - May 1999
based on code from the book "Java Network Programming" by Hughes
*/

package encryption;

/**This class is the generic superclass for all hash functions. Hash
functions are used to compute message digests; a message digest is, as the
name suggests, a summary of the message.*/

public abstract class Hash {

/**Returns a digest from the subarray of text consisting of len bytes,
from offset off.*/

public abstract byte[] digest (byte[] text, int off, int len);

/**Computes a digest for the whole array text using the previous method.*/

public byte[] digest (byte[] text) {
	return digest (text, 0, text.length);
}

/**Returns the digest size returned by this algorithm. MD5 returns 16
bytes. SHS returns 20 bytes.*/

public abstract int digestSize();

} /*end of class Hash*/