java结合keytool如何实现非对称签名和验证详解

$ keytool -genkey -alias signLegal -keystore examplestanstore -validity 1800

$ keytool -list -keystore examplestanstore -v

$ keytool -export -keystore examplestanstore -alias signLegal -file StanSmith.cer

$ java GenSig hello.txt   (生成文件sig和suepk)
$ java VerSig suepk sig hello.txt
signature verifies: true

import java.io.*;
import java.security.*;

class GenSig2 {

 public static void main(String[] args) {

 if (args.length != 1) {
  System.out.println("Usage: java GenSig2 <nameOfFileToSign>");
  }
 else try{

  /*create key paire use keytool:
  $ keytool -genkey -alias signLegal -keystore examplestanstore -validity 1800*/
  // read keystore file
  KeyStore ks = KeyStore.getInstance("JKS");
  FileInputStream ksfis = new FileInputStream("examplestanstore");
  BufferedInputStream ksbufin = new BufferedInputStream(ksfis);

  // open keystore and get private key
  // alias is 'signLeal', kpasswd/spasswd is 'vagrant'
  ks.load(ksbufin, "vagrant".toCharArray());
  PrivateKey priv = (PrivateKey) ks.getKey("signLegal", "vagrant".toCharArray());

  /* Create a Signature object and initialize it with the private key */

  Signature dsa = Signature.getInstance("SHA1withDSA", "SUN");

  dsa.initSign(priv);
  /* Update and sign the data */

  FileInputStream fis = new FileInputStream(args[0]);
  BufferedInputStream bufin = new BufferedInputStream(fis);
  byte[] buffer = new byte[1024];
  int len;
  while (bufin.available() != 0) {
  len = bufin.read(buffer);
  dsa.update(buffer, 0, len);
  };

  bufin.close();

  /* Now that all the data to be signed has been read in,
   generate a signature for it */
  byte[] realSig = dsa.sign();

  /* Save the signature in a file */
  FileOutputStream sigfos = new FileOutputStream("sig");
  sigfos.write(realSig);

  sigfos.close();

  /* public key file can export from keystore use keytool:
  $ keytool -export -keystore examplestanstore -alias signLegal -file StanSmith.cer */

 } catch (Exception e) {
  System.err.println("Caught exception " + e.toString());
 }
 };

$ java GenSig2 hello.txt

import java.io.*;
import java.security.*;
import java.security.spec.*;

class VerSig2 {

 public static void main(String[] args) {

 /* Verify a DSA signature */

 if (args.length != 3) {
  System.out.println("Usage: VerSig publickeyfile signaturefile datafile");
  }
 else try{

  /* import encoded public cert */
  FileInputStream certfis = new FileInputStream(args[0]);
  java.security.cert.CertificateFactory cf =
  java.security.cert.CertificateFactory.getInstance("X.509");
  java.security.cert.Certificate cert = cf.generateCertificate(certfis);
  PublicKey pubKey = cert.getPublicKey();

  /* input the signature bytes */
  FileInputStream sigfis = new FileInputStream(args[1]);
  byte[] sigToVerify = new byte[sigfis.available()];
  sigfis.read(sigToVerify );

  sigfis.close();

  /* create a Signature object and initialize it with the public key */
  Signature sig = Signature.getInstance("SHA1withDSA", "SUN");
  sig.initVerify(pubKey);

  /* Update and verify the data */

  FileInputStream datafis = new FileInputStream(args[2]);
  BufferedInputStream bufin = new BufferedInputStream(datafis);
  byte[] buffer = new byte[1024];
  int len;
  while (bufin.available() != 0) {
  len = bufin.read(buffer);
  sig.update(buffer, 0, len);
  };

  bufin.close();

  boolean verifies = sig.verify(sigToVerify);

  System.out.println("signature verifies: " + verifies);

 } catch (Exception e) {
  System.err.println("Caught exception " + e.toString());
 };
 }
}

$ java VerSig2 StanSmith.cer sig hello.txt
signature verifies: true

$ openssl genrsa -out key.pem 1024
$ cat key.pem
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

$ openssl rsa -in key.pem -pubout -out pub-key.pem
$ cat pub-key.pem
-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCzVDmu6Cf2QF7cERCGYU3B8Epm
6pkkpMZFgotphXMgAmBBNJbhSi7qPH4R5JlEm1ZXPr5DZH/pyJBWQhiiHGeUAOve
+GOgvt9Rk25r7OEWYvn/GCr/JBfLBGqwtlzn/t2s2x04IooshsGkOd6YpZoztkED
tu2gKHedFczF607IvwIDAQAB
-----END PUBLIC KEY-----

$ cat hello.txt
1234
$ openssl dgst -SHA256 -out hello.sha256 hello.txt
$ cat hello.sha256
SHA256(hello.txt)= a883dafc480d466ee04e0d6da986bd78eb1fdd2178d04693723da3a8f95d42f4

$ openssl rsautl -sign -in hello.sha256 -out hello.sign -inkey key.pem

$ openssl rsautl -verify -in hello.sign -inkey pub-key.pem -pubin
SHA256(hello.txt)= a883dafc480d466ee04e0d6da986bd78eb1fdd2178d04693723da3a8f95d42f4

$ openssl rsautl -verify -in hello.sign -inkey key.pem
SHA256(hello.txt)= a883dafc480d466ee04e0d6da986bd78eb1fdd2178d04693723da3a8f95d42f4