- Message Digest MD5 and SHA

This section describes 2 popular message digest algorithm, MD5 and SHA, implemented in JDK as part of the JCA (Java Cryptography Architecture) package.

What Is Message Digest? Message digest is a one-way hash function that takes arbitrary-sized data and outputs a fixed-length hash value.

Known message digest algorithms are:

Message digest is supported in JDK as part of the JCA (Java Cryptography Architecture) package, which has been included in JDK since 1.1:

In JCA, the class is an abstract class providing a link to implementation classes of message digest algorithms provided by various security package providers. Major methods in the MessageDigest class are:

getInstance() - Returns a message digest object of the specified algorithm from the implementation of the specified provider. If provider is not specified, the default implementation is used. This is a static method.

update() - Adds more data to the current message digest object for processing.

digest() - Returns the digest data of the input data processed so far in the current message digest object. It also removes the input data received in the object.

getAlgorithm() - Returns the algorithm name of the current message digest object.

getProvider() - Returns the provider as a provider object of the current message digest object.

See the next section for a sample program of using the MessageDigest class.

Last update: 2014.

Table of Contents

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 Downloading and Installing JDK 1.8.0 on Windows

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Message Digest Algorithm Implementations in JDK - Message Digest MD5 and SHA - 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

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 HTTPS (Hypertext Transfer Protocol Secure)

 Outdated Tutorials


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