Java IO.pdf - Nguyen Dang Binh

A.5 Data Compression
Java I/O
Java supports several related compression formats, including zlib, deflate, and gzip. These
formats are documented in RFCs 1950, 1951, and 1952, and are available wherever RFCs are
found, including http://www.faqs.org/rfcs/. The master site for these particular RFCs is
ftp://ftp.uu.net/graphics/png/documents/zlib/zdoc-index.html.
Java's compression classes are native wrappers around the ZLIB compression library written
by Jean-Loup Gailly and Mark Adler. You can learn about this library at
http://www.cdrom.com/pub/infozip/zlib/.
For more general information about compression and archiving algorithms and formats, the
comp.compression FAQ is a good place to start. See http://www.faqs.org/faqs/compressionfaq/part1/preamble.html.
More technical details and sample code in C for a variety of
algorithms are available in The Data Compression Book, by Mark Nelson and Jean-Loup
Gailly (M&T Books, 1996, ISBN 1-55851-434-1).
The JAR file format was developed by Sun for Java. The full specification can be found at
http://java.sun.com/products/jdk/1.2/docs/guide/jar/jarGuide.html ( Java 2) or
http://java.sun.com/products/jdk/1.1/docs/guide/jar/jarGuide.html ( Java 1.1). Aside from the
name, the only thing that really distinguishes a JAR file from a zip file is the optional
manifest of the contents. The manifest format specification can be found at
http://java.sun.com/products/jdk/1.2/docs/guide/jar/manifest.html.
A.6 Encryption and Related Technology
Chapter 10 only began to explore the fascinating subject of cryptography. The JCE is
explicated in much more detail by Jonathan Knudsen in Java Cryptography (O'Reilly &
Associates, 1998) Java Cryptography expands on the coverage of the Cipher and
MessageDigest classes you'll find in this book. It also includes thorough discussions of the
java.security package and the Java Cryptography Extension (JCE), showing you how to
use security providers and even implement your own provider. It discusses authentication, key
management, and public and private key encryption and includes a secure talk application that
encrypts all data sent over the network. If you write Java programs that communicate
sensitive data, you'll find this book indispensable.
For a more in-depth look at the mathematics and protocols that underlie the JCE, you'll want
to check out Bruce Schneier's Applied Cryptography (John Wiley & Sons, 1995). This is the
standard practical text on cryptographic protocols and algorithms, and the attacks on them.
Schneier discusses a wide range of cryptographic algorithms, key management and exchange
schemes, one-way hash functions, signature algorithms, and many other problems in
sufficient detail to allow a competent programmer to implement them. Although Schneier's
language of choice is C, the techniques discussed are applicable in any language.
The formal specification of the Java Cryptography API is available from Sun at
http://java.sun.com/products/jdk/1.2/docs/guide/security/CryptoSpec.html. The actual
implementation is in beta at the time of this writing and can be downloaded from
http://developer.java.sun.com/developer/earlyAccess/jdk12/jce.html.
461