Cryptography Tutorials - Herong's Tutorial Examples - v5.42, by Herong Yang
DsaSignatureGenerator.java - Generating DSA Digital Signature
This section provides tutorial example on how to generate a digital signature for a message file with a DSA private key using the SHA1withDSA algorithm.
Here my DSA signature generation program, DsaSignatureGenerator.java, using the java.security.Signature class:
/* DsaSignatureGenerator.java * Copyright (c) HerongYang.com. All Rights Reserved. */ import java.io.*; import java.security.*; import java.security.spec.*; class DsaSignatureGenerator { public static void main(String[] a) { if (a.length<3) { System.out.println("Usage:"); System.out.println("java DsaSignatureGenerator keyFile" + " msgFile sigFile"); return; } String keyFile = a[0]; String msgFile = a[1]; String sigFile = a[2]; String keyAlgo = "DSA"; String sigAlgo = "SHA1withDSA"; try { PrivateKey priKey = readPrivateKey(keyFile,keyAlgo); sign(msgFile,sigFile,sigAlgo,priKey); } catch (Exception e) { System.out.println("Exception: "+e); return; } } private static PrivateKey readPrivateKey(String input, String algorithm) throws Exception { KeyFactory keyFactory = KeyFactory.getInstance(algorithm); FileInputStream priKeyStream = new FileInputStream(input); int priKeyLength = priKeyStream.available(); byte[] priKeyBytes = new byte[priKeyLength]; priKeyStream.read(priKeyBytes); priKeyStream.close(); PKCS8EncodedKeySpec priKeySpec = new PKCS8EncodedKeySpec(priKeyBytes); PrivateKey priKey = keyFactory.generatePrivate(priKeySpec); System.out.println(); System.out.println("Private Key Info: "); System.out.println("Algorithm = "+priKey.getAlgorithm()); return priKey; } private static byte[] sign(String input, String output, String algorithm, PrivateKey priKey) throws Exception { Signature sg = Signature.getInstance(algorithm); sg.initSign(priKey); System.out.println(); System.out.println("Signature Object Info: "); System.out.println("Algorithm = "+sg.getAlgorithm()); System.out.println("Provider = "+sg.getProvider()); FileInputStream in = new FileInputStream(input); int bufSize = 1024; byte[] buffer = new byte[bufSize]; int n = in.read(buffer,0,bufSize); int count = 0; while (n!=-1) { count += n; sg.update(buffer,0,n); n = in.read(buffer,0,bufSize); } in.close(); FileOutputStream out = new FileOutputStream(output); byte[] sign = sg.sign(); out.write(sign); out.close(); System.out.println(); System.out.println("Sign Processing Info: "); System.out.println("Number of input bytes = "+count); System.out.println("Number of output bytes = "+sign.length); return sign; } }
Some notes on DsaSignatureGenerator.java:
Table of Contents
Introduction to AES (Advanced Encryption Standard)
DES Algorithm - Illustrated with Java Programs
DES Algorithm Java Implementation
DES Algorithm - Java Implementation in JDK JCE
DES Encryption Operation Modes
PHP Implementation of DES - mcrypt
Blowfish - 8-Byte Block Cipher
Secret Key Generation and Management
Cipher - Secret Key Encryption and Decryption
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
OpenSSL Introduction and Installation
OpenSSL Generating and Managing RSA Keys
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"