java.security.Signature - The Data Signing Class

This section describes the data signing and verification Java class, java.security.Signature, and its major methods like update(), sign() and verify().

The java.security.Signature class is an abstract class providing a link to implementation classes of digital signature algorithms provided by various security package providers. Major methods in the KeyPairGenerator class:

getInstance() - Returns a Signature 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.

initSign() - Initializes the current Signature object with the specified private key to be ready to take input data for generating a new signature.

initVerify() - Initializes the current Signature object with the specified public key to be ready to take input data for verifying an existing signature.

update() - Adds more data to the current Signature object for signature generation or signature verification.

sign() - Generates a new signature for the input data received so far in the current Signature object, and returns the signature as a byte array. It also removes the input data.

verify() - Verifies the input data received so far in the current Signature object against the specified signature, and returns true or false. It also removes the input data.

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

getProvider() - Returns the provider as a Provider object of the current Signature object.

See the next section on how to write a sample program.

Last update: 2013.

Table of Contents

 About This Book

 Cryptography Terminology

 Cryptography Basic Concepts

 Introduction to AES (Advanced Encryption Standard)

 Introduction to DES Algorithm

 DES Algorithm - Illustrated with Java Programs

 DES Algorithm Java Implementation

 DES Algorithm - Java Implementation in JDK JCE

 DES Encryption Operation Modes

 DES in Stream Cipher Modes

 PHP Implementation of DES - mcrypt

 Blowfish - 8-Byte Block Cipher

 Secret Key Generation and Management

 Cipher - Secret Key Encryption and Decryption

 Introduction of RSA Algorithm

 RSA Implementation using java.math.BigInteger Class

 Introduction of DSA (Digital Signature Algorithm)

Java Default Implementation of DSA

 DsaKeyGenerator.java - Generating DSA Key Pair

 DSA 512-bit and 1024-bit Key Pair Examples

 DsaKeyChecker.java - Reading and Checking DSA Keys

 Example of DSA Key Parameters and Properties

java.security.Signature - The Data Signing Class

 DsaSignatureGenerator.java - Generating DSA Digital Signature

 DsaSignatureGenerator.java Test Results

 DsaSignatureVerifier.java - Verifying DSA Digital Signature

 DsaSignatureVerifier.java Test Results

 Private key and Public Key Pair Generation

 PKCS#8/X.509 Private/Public Encoding Standards

 Cipher - Public Key Encryption and Decryption

 MD5 Mesasge Digest Algorithm

 SHA1 Mesasge Digest Algorithm

 OpenSSL Introduction and Installation

 OpenSSL Generating and Managing RSA Keys

 OpenSSL Managing Certificates

 OpenSSL Generating and Signing CSR

 OpenSSL Validating Certificate Path

 "keytool" and "keystore" from JDK

 "OpenSSL" Signing CSR Generated by "keytool"

 Migrating Keys from "keystore" to "OpenSSL" Key Files

 Certificate X.509 Standard and DER/PEM Formats

 Migrating Keys from "OpenSSL" Key Files to "keystore"

 Using Certificates in IE (Internet Explorer)

 Using Certificates in Firefox

 Using Certificates in Google Chrome

 Outdated Tutorials

 References

 PDF Printing Version