數字簽名算法RSA

package signature;

import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.SignatureException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import org.apache.commons.codec.binary.Hex;


public class RSA {
    
    private static String src = "鄧貴坤";
    public static void main(String[] args) {
        RSAj();
    }
    
    public static void RSAj(){
        try {
            //初始化簽名
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            keyPairGenerator.initialize(512);
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();//公鑰
            RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();//祕鑰
            
            //執行簽名
            PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
            Signature signature = Signature.getInstance("MD5withRSA");
            signature.initSign(privateKey);
            signature.update(src.getBytes());
            byte[] result = signature.sign();//使用私鑰進行簽名
            System.out.println("jdk RSA簽名" + Hex.encodeHexString(result));
        
            //驗證簽名
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
            keyFactory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
            signature = Signature.getInstance("MD5withRSA");
            signature.initVerify(publicKey);
            signature.update(src.getBytes());
            boolean bool = signature.verify(result);//使用公鑰進行驗證
            System.out.println("jdk RSA 簽名" + bool);
            
            
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (InvalidKeySpecException e) {
            e.printStackTrace();
        } catch (SignatureException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
}


①發送方構建密鑰對
②將祕鑰公佈給夥伴
③使用私鑰簽名
④將簽名和數據發送給夥伴
⑤夥伴使用公鑰簽名驗證數據