Class SpiderEntropy

java.lang.Object
   |
   +----SpiderEntropy

public class SpiderEntropy

extends Object

Netrand Project

Software Engineering - CS536

University of Wisconsin - Milwaukee

Authors:

• Spring 1998 - Francis William Kasper

The SpiderEntropy object is used with a web spider to obtain entropy from the internet. As the web spider travels across the network, the SpiderEntropy object compresses the html files it encounters, extracts bytes from the compressed file, and hashes those bytes using the HashMD5 class. The hashed value is then XORed with the previous html file's hash value. The resulting hash value is used as entropy and sent to a server using the BitSender class.

compressedFile

the compressed version of the current html file

lastByte

contains the random byte from the previous HTML file

SpiderEntropy()

CompressFile(File)

takes a given file and compresses it using GZIP

getRandomBlock()

From the cached compressed file, 64 bytes are extracted from the file to be used as input to the HashMD5 hash function.

MineEntropy(File)

This function calls the appropriate functions for obtaining random bits from a specific file.

 private static byte lastByte

contains the random byte from the previous HTML file

 private static File compressedFile

the compressed version of the current html file

 public SpiderEntropy()

 public static void MineEntropy(File aFile)

This function calls the appropriate functions for obtaining random bits from a specific file. It calls the functions to compress the file, hash a section of the file, and form the random set of bits. These bits are sent to the server by a BitSender object.

Parameters:

aFile - - the file to mine the entropy from

 private static void CompressFile(File aFile) throws Exception

takes a given file and compresses it using GZIP

Parameters:

aFile - - the file to compress

Throws: Exception

if the file failes to compress properly

 private static byte[] getRandomBlock() throws Exception

From the cached compressed file, 64 bytes are extracted from the file to be used as input to the HashMD5 hash function. The selection of the bytes is done by partitioning the file into 64 subblocks. The offset into the subblocks is determined by the current time in milliseconds mod the subblock size.

Returns:

the random block of 64 bytes from the compressed file

Throws: Exception

if there was a problem reading bytes from the compressed file.