java RSA 加解密

java RSA 加解密

  import java.security.Key;

  import java.security.KeyFactory;

  import java.security.KeyPair;

  import java.security.KeyPairGenerator;

  import java.security.PrivateKey;

  import java.security.PublicKey;

  import java.security.interfaces.RSAPrivateKey;

  import java.security.interfaces.RSAPublicKey;

  import java.security.spec.PKCS8EncodedKeySpec;

  import java.security.spec.X509EncodedKeySpec;

  import javax.crypto.Cipher;

  import sun.misc.BASE64Decoder;

  import sun.misc.BASE64Encoder;

  public class RSACoder {

  /**

  * 得到公钥

  * @param key 密钥字符串(经过base64编码)

  * @throws Exception

  */

  public static PublicKey getPublicKey(String key) throws Exception {

  byte[] keyBytes;

  keyBytes = (new BASE64Decoder()).decodeBuffer(key);

  X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);

  KeyFactory keyFactory = KeyFactory.getInstance("RSA");

  PublicKey publicKey = keyFactory.generatePublic(keySpec);

  return publicKey;

  }

  /**

  * 得到私钥

  * @param key 密钥字符串(经过base64编码)

  * @throws Exception

  */

  public static PrivateKey getPrivateKey(String key) throws Exception {

  byte[] keyBytes;

  keyBytes = (new BASE64Decoder()).decodeBuffer(key);

  PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);

  KeyFactory keyFactory = KeyFactory.getInstance("RSA");

  PrivateKey privateKey = keyFactory.generatePrivate(keySpec);

  return privateKey;

  }
  /**

  * 得到密钥字符串(经过base64编码)

  * @return

  */

  public static String getKeyString(Key key) throws Exception {

  byte[] keyBytes = key.getEncoded();

  String s = (new BASE64Encoder()).encode(keyBytes);

  return s;

  }

  public static void main(String[] args) throws Exception {

  KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");

  //密钥位数

  keyPairGen.initialize(1024);

  //密钥对

  KeyPair keyPair = keyPairGen.generateKeyPair();

  // 公钥

  PublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

  // 私钥

  PrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

  String publicKeyString = getKeyString(publicKey);

  System.out.println("public:\n" + publicKeyString);

  String privateKeyString = getKeyString(privateKey);

  System.out.println("private:\n" + privateKeyString);

  //加解密类

  Cipher cipher = Cipher.getInstance("RSA");//Cipher.getInstance("RSA/ECB/PKCS1Padding");

  //明文

  byte[] plainText = "我们都很好!邮件:@sina.com".getBytes();

  //加密

  cipher.init(Cipher.ENCRYPT_MODE, publicKey);

  byte[] enBytes = cipher.doFinal(plainText);

  //通过密钥字符串得到密钥

  publicKey = getPublicKey(publicKeyString);

  privateKey = getPrivateKey(privateKeyString);

  //解密

  cipher.init(Cipher.DECRYPT_MODE, privateKey);

  byte[]deBytes = cipher.doFinal(enBytes);

  publicKeyString = getKeyString(publicKey);

  System.out.println("public:\n" +publicKeyString);

  privateKeyString = getKeyString(privateKey);

  System.out.println("private:\n" + privateKeyString);

  String s = new String(deBytes);

  System.out.println(s);

  }

  }



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