DSA签名算法的Java实现

package JavaInteropSign; import java.io.*; import java.security.*; import java.security.spec.*; import javax.swing.JOptionPane; /** * @author jeffrey walton **/ public class Main { static String ALGORITHM = "DSA"; public static void main(String[] args) { try { CreateDSAKeys(); SignDSAMessage(); VerifyDSAMessage(); } catch (Exception e) { System.err.println("Main: Exception " + e.toString()); } } private static void VerifyDSAMessage() { try { // Load the public PublicKey publicKey = LoadPublicKey("public.dsa.java.key"); // Load the message from file FileInputStream mis = new FileInputStream("dsa.java.msg"); byte[] message = new byte[mis.available()]; mis.read(message); mis.close(); // Display the resurrected string JOptionPane.showMessageDialog(null, new String(message, 0, message.length, "UTF-8")); // Load the signature of the message from file FileInputStream sis = new FileInputStream("dsa.java.sig"); byte[] signature = new byte[sis.available()]; sis.read(signature); sis.close(); // Initialize Signature Object Signature verifier = Signature.getInstance(ALGORITHM); verifier.initVerify(publicKey); // Load the message into the Verifier Object verifier.update(message); // Verify the Signature on the Message boolean result = verifier.verify(signature); StringBuilder sb = new StringBuilder(); if( result ) { sb.append("Message Verified:\n"); sb.append(new String(message, 0, message.length, "UTF-8")); } else { sb.append("Message Not Verified"); } JOptionPane.showMessageDialog(null, sb.toString()); } catch (Exception e) { System.err.println("VerifyDSAMessage: " + e.toString()); } } private static void SignDSAMessage() { try { // Retrieve the Private Key PrivateKey privateKey = LoadPrivateKey("private.dsa.java.key"); // Create the signer object Signature signer = Signature.getInstance(ALGORITHM); signer.initSign(privateKey, new SecureRandom()); // Prepare the Message String s = "Crypto Interop: \u9aa8"; // Save the binary of the String which we will sign byte[] message = s.getBytes("UTF-8"); // Insert the message into the signer object signer.update(message); byte[] signature = signer.sign(); // mos: message filestream // sos: signature filestream FileOutputStream mos = new FileOutputStream("dsa.java.msg"); mos.write(message); FileOutputStream sos = new FileOutputStream("dsa.java.sig"); sos.write(signature); } catch (Exception e) { System.err.println("SignDSAMessage: " + e.toString()); } } private static PublicKey LoadPublicKey(String filename) { PublicKey key = null; try { FileInputStream fis = new FileInputStream(filename); byte[] b = new byte[fis.available()]; fis.read(b); fis.close(); X509EncodedKeySpec spec = new X509EncodedKeySpec(b); KeyFactory factory = KeyFactory.getInstance(ALGORITHM); key = factory.generatePublic(spec); } catch (Exception e) { System.err.println("LoadPublicKey: " + e.toString()); } return key; } private static PrivateKey LoadPrivateKey( String filename) { PrivateKey key = null; try { FileInputStream fis = new FileInputStream(filename); byte[] b = new byte[fis.available()]; fis.read(b); fis.close(); PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(b); KeyFactory factory = KeyFactory.getInstance("DSA"); key = factory.generatePrivate(spec); } catch (Exception e) { System.err.println("LoadPrivateKey: " + e.toString()); } return key; } private static void CreateDSAKeys() throws NoSuchAlgorithmException { // http://java.sun.com/j2se/1.4.2/docs/guide/security/CryptoSpec.html // KeyPairGenerator kpg = KeyPairGenerator.getInstance("DSA", "SUN"); KeyPairGenerator kpg = KeyPairGenerator.getInstance(ALGORITHM); kpg.initialize(1024, new SecureRandom()); KeyPair keys = kpg.generateKeyPair(); PrivateKey privateKey = keys.getPrivate(); PublicKey publicKey = keys.getPublic(); // Serialize Keys SaveKey("private.dsa.java.key", privateKey); SaveKey("public.dsa.java.key", publicKey); } static void SaveKey(String filename, Key key) { try { if (null == key) { throw new Exception("key is null."); } FileOutputStream fos = new FileOutputStream(filename); // PKCS #8 for Private, X.509 for Public // File will contain OID 1.2.840.10040.4.1 (DSA) // http://java.sun.com/j2se/1.4.2/docs/api/java/security/Key.html fos.write(key.getEncoded()); fos.close(); } catch (Exception e) { System.err.println("SaveEncodedKey: Exception " + e.toString()); } } }