JDK Tutorials - Herong's Tutorial Examples - v6.32, by Herong Yang
Comparing Message Digest Output of MD5 and SHA
This section a tutorial example on how to view and compare message digest output from two standard message digest algorithms MD5 and SHA.
The message digest output file contains binary data, which cannot be viewed directly. In order to see the digest data, I need to use my other program, HexWriter.java, to convert binary data to hex numbers. See chapter "Encoding Conversion" for details.
Here is how to look at the digest data in hex numbers, 16 bytes per line:
herong> javac HexWriter.java herong> java HexWriter digest.sha digest_sha.hex herong> more digest_sha.hex 0520E172B3E334C9BDD92D7ADBC98F1C BD4162D0
My second test is to see the digest data of the same input data, JcaMessageDigest.class, using MD5 algorithm:
herong> java JcaMessageDigest JcaMessageDigest.class digest.md5 MD5 MessageDigest Object Info: Algorithm = MD5 Provider = SUN version 10 Digest Length = 16 toString = MD5 Message Digest from SUN, <initialized> Message Digest Processing Info: Number of input bytes = 2555 Number of output bytes = 16 herong> java HexWriter digest.md5 digest_md5.hex herong> more digest_md5.hex 7DA3B53BBEC296D835DC58A1AD5FA664
My third test is to see how the digest data changes if I add one byte to the input data:
herong> copy con dot.tmp .^Z herong> copy JcaMessageDigest.class JcaMessageDigest_1.class herong> more dot.tmp >> JcaMessageDigest_1.class herong> dir *.class 2,217 JcaMessageDigest.class 2,218 JcaMessageDigest_1.class herong> java JcaMessageDigest JcaMessageDigest_1.class digest_1.md5 MD5 MessageDigest Object Info: Algorithm = MD5 Provider = SUN version 1.8 Digest Length = 16 toString = MD5 Message Digest from SUN, <initialized> Message Digest Processing Info: Number of input bytes = 2218 Number of output bytes = 16 herong> java HexWriter digest_1.md5 digest_1_md5.hex herong> more digest_1_md5.hex 31B82738B990A2ECDA63547B660CA0F0
A couple of interesting notes here:
Table of Contents
Date, Time and Calendar Classes
Date and Time Object and String Conversion
Number Object and Numeric String Conversion
Locales, Localization Methods and Resource Bundles
Calling and Importing Classes Defined in Unnamed Packages
HashSet, Vector, HashMap and Collection Classes
Character Set Encoding Classes and Methods
Encoding Conversion Programs for Encoded Text Files
Datagram Network Communication
DOM (Document Object Model) - API for XML Files
DTD (Document Type Definition) - XML Validation
XSD (XML Schema Definition) - XML Validation
XSL (Extensible Stylesheet Language)
►Message Digest Algorithm Implementations in JDK
java.security.MessageDigest - Message Digest MD5 and SHA
JcaMessageDigest.java - Message Digest Sample Program
►Comparing Message Digest Output of MD5 and SHA
Private key and Public Key Pair Generation
PKCS#8/X.509 Private/Public Encoding Standards
Digital Signature Algorithm and Sample Program
"keytool" Commands and "keystore" Files
KeyStore and Certificate Classes
Secret Key Generation and Management
Cipher - Encryption and Decryption
The SSL (Secure Socket Layer) Protocol
SSL Socket Communication Testing Programs