key-management - 如何从我们创建的 keystore 中检索我的公钥和私钥

Question

我的任务如下:

• 从我创建的 keystore 中检索我的公钥和私钥。
• 使用这些 key 使用我的 RSA 2048 位公钥加密段落。
• 使用 DSA-SHA-1 签名算法对结果进行数字签名。
• 将数字签名输出保存在名为 output.dat 的文件中。

下面的程序抛出错误:“java.security.InvalidKeyException:没有安装的提供程序支持此 key :sun.security.provider.DSAPublicKeyImpl”。

import java.security.*;
import java.security.KeyStore.*;
import java.io.*;
import java.security.PublicKey;
import java.security.PrivateKey;
import javax.crypto.Cipher;
import java.nio.charset.*;
import sun.security.provider.*;
import  javax.crypto.*;

public class Code {

/**
 * @param args the command line arguments
 */
    public static void main(String[] args) {

        try {

            /* getting data for keystore */

            File file = new File(System.getProperty("user.home") + File.separatorChar + ".keystore");
            FileInputStream is = new FileInputStream(file);
            KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());

            /*Information for certificate to be generated */ 
            String password = "abcde";
            String alias = "mykeys";
            String alias1 = "skeys";

            String filepath ="C:\\email.txt";

            /* getting the key*/
            keystore.load(is, password.toCharArray());
            PrivateKey key = (PrivateKey)keystore.getKey(alias, "bemylife".toCharArray());
            //PrivateKey key = cert1.getPrivateKey();
            //PublicKey key1= (PrivateKey)key;

            /* Get certificate of public key */
            java.security.cert.Certificate cert = keystore.getCertificate(alias); 

            /* Here it prints the public key*/
            System.out.println("Public Key:");
            System.out.println(cert.getPublicKey());

            /* Here it prints the private key*/
            System.out.println("\nPrivate Key:");
            System.out.println(key);

            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE,cert.getPublicKey());

            String cleartextFile = "C:\\email.txt";
            String ciphertextFile = "D:\\ciphertextRSA.png";

            FileInputStream fis = new FileInputStream(cleartextFile);
            FileOutputStream fos = new FileOutputStream(ciphertextFile);
            CipherOutputStream cos = new CipherOutputStream(fos, cipher);

            byte[] block = new byte[32];
            int i;
            while ((i = fis.read(block)) != -1) {
                cos.write(block, 0, i);
            }
            cos.close();


            /* computing the signature*/
            Signature dsa = Signature.getInstance("SHA1withDSA", "SUN");
            dsa.initSign(key);
            FileInputStream f = new FileInputStream(ciphertextFile);
            BufferedInputStream in = new BufferedInputStream(f);
            byte[] buffer = new byte[1024];
            int len;
            while ((len = in.read(buffer)) >= 0) {
               dsa.update(buffer, 0, len);
           };
           in.close();

           /* Here it prints the signature*/
           System.out.println("Digital Signature :");
           System.out.println( dsa.sign());

           /* Now Exporting Certificate */
           System.out.println("Exporting Certificate. ");
           byte[] buffer_out = cert.getEncoded();
           FileOutputStream os = new FileOutputStream(new File("d:\\signedcetificate.cer"));
           os.write(buffer_out);
           os.close();

           /* writing signature to output.dat file */
           byte[] buffer_out1 = dsa.sign();
           FileOutputStream os1 = new FileOutputStream(new File("d:\\output.dat"));
           os1.write(buffer_out1);
           os1.close();

       } catch (Exception e) {System.out.println(e);}

   }
}

Answer 1

您必须将其从 keystore 文件(可能以 .jks 结尾)读取到 java.security.KeyStore 中目的。

/**
 * Reads a Java keystore from a file.
 * 
 * @param keystoreFile
 *          keystore file to read
 * @param password
 *          password for the keystore file
 * @param keyStoreType
 *          type of keystore, e.g., JKS or PKCS12
 * @return the keystore object
 * @throws KeyStoreException
 *           if the type of KeyStore could not be created
 * @throws IOException
 *           if the keystore could not be loaded
 * @throws NoSuchAlgorithmException
 *           if the algorithm used to check the integrity of the keystore
 *           cannot be found
 * @throws CertificateException
 *           if any of the certificates in the keystore could not be loaded
 */
public static KeyStore loadKeyStore(final File keystoreFile,
    final String password, final String keyStoreType)
    throws KeyStoreException, IOException, NoSuchAlgorithmException,
    CertificateException {
  if (null == keystoreFile) {
    throw new IllegalArgumentException("Keystore url may not be null");
  }
  LOG.debug("Initializing key store: {}", keystoreFile.getAbsolutePath());
  final URI keystoreUri = keystoreFile.toURI();
  final URL keystoreUrl = keystoreUri.toURL();
  final KeyStore keystore = KeyStore.getInstance(keyStoreType);
  InputStream is = null;
  try {
    is = keystoreUrl.openStream();
    keystore.load(is, null == password ? null : password.toCharArray());
    LOG.debug("Loaded key store");
  } finally {
    if (null != is) {
      is.close();
    }
  }
  return keystore;
}

一旦您拥有KeyStore，您就可以获得Certificate以及公钥和私钥。

但是使用它来签署文本并将其保存在文件中更加复杂，而且容易出错。看看Sign string using given Public Key并将 getKeyPair 方法替换为使用 KeyStore 的方法。类似

的东西

public static KeyPair getKeyPair(final KeyStore keystore, 
    final String alias, final String password) {
  final Key key = (PrivateKey) keystore.getKey(alias, password.toCharArray());

  final Certificate cert = keystore.getCertificate(alias);
  final PublicKey publicKey = cert.getPublicKey();

  return KeyPair(publicKey, (PrivateKey) key);
}

(显然有点粗糙，我手头没有 sample )