數(shù)據(jù)安全管理：RSA加密算法，簽名驗簽流程詳解

本文源碼：GitHub·點這里 || GitEE·點這里

一、RSA算法簡介

1、加密解密

RSA加密是一種非對稱加密，在公開密鑰加密和電子商業(yè)中RSA被廣泛使用?？梢栽诓恢苯觽鬟f密鑰的情況下，完成加解密操作。這能夠確保信息的安全性，避免了直接傳遞密鑰所造成的被破解的風(fēng)險。是由一對密鑰來進行加解密的過程，分別稱為公鑰和私鑰。該加密算法的原理就是對一極大整數(shù)做因數(shù)分解的困難性來保證安全性。

2、簽名驗簽

數(shù)字簽名就是信息的來源添加一段無法被偽造的加密字符串，這段數(shù)字串作為對信息的來源真實性的一個有效證明。這個過程稱為簽名和驗簽。

二、場景描述

• 消息發(fā)送方：甲方，持有公鑰
• 消息接收方：乙方，持有私鑰

1、加密解密過程

(1)、乙方生成一對密鑰即公鑰和私鑰，私鑰不公開，乙方自己持有，公鑰為公開，甲方持有。

(2)、乙方收到甲方加密的消息，使用私鑰對消息進行解密，獲取明文。

2、簽名驗簽過程

(1)、乙方收到消息后，需要回復(fù)甲方，用私鑰對回復(fù)消息簽名，并將消息明文和消息簽名回復(fù)甲方。

(2)、甲方收到消息后，使用公鑰進行驗簽，如果驗簽結(jié)果是正確的，則證明消息是乙方回復(fù)的。

三、源代碼實現(xiàn)

1、密鑰字符串獲取

• 代碼生成

  private static HashMap<String, String> getTheKeys() {
  HashMap<String, String> keyPairMap = new HashMap<String, String>();
  KeyPairGenerator keyPairGen = null;
  try {
      keyPairGen = KeyPairGenerator.getInstance("RSA");
  } catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
  }
  // 密鑰大?。?024 位
  keyPairGen.initialize(1024);
  KeyPair keyPair = keyPairGen.generateKeyPair();
  String publicKey = printBase64Binary(keyPair.getPublic().getEncoded());
  String privateKey = printBase64Binary(keyPair.getPrivate().getEncoded());
  keyPairMap.put("publicKey", publicKey);
  keyPairMap.put("privateKey", privateKey);
  return keyPairMap ;
  }

• 讀取文件

文件位置

public static final String PUB_KEY = "rsaKey/public.key" ;
public static final String PRI_KEY = "rsaKey/private.key" ;

文件加載

public static String getKey (String keyPlace) throws Exception {
    BufferedReader br= null;
    try {
        br= new BufferedReader(new InputStreamReader(RsaCryptUtil.class.getClassLoader().
                                                     getResourceAsStream(keyPlace)));
        String readLine= null;
        StringBuilder keyValue = new StringBuilder();
        while((readLine= br.readLine())!=null){
            if(!(readLine.charAt(0)=='-')){
                keyValue.append(readLine);
            }
        }
        return keyValue.toString();
    } catch (Exception e) {
        throw new Exception("RSA密鑰讀取錯誤",e) ;
    } finally{
        if (br != null) {
            try {
                br.close();
            } catch (Exception e) {
                System.out.println("密鑰讀取流關(guān)閉異常");
            }
        }
    }
}

2、公鑰和私鑰

• 公鑰字符串生成公鑰

  public static RSAPublicKey createPublicKey(String publicKeyValue) throws Exception {
  try {
      byte[] buffer = DatatypeConverter.parseBase64Binary(publicKeyValue);
      KeyFactory keyFactory = KeyFactory.getInstance("RSA");
      X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
      return (RSAPublicKey) keyFactory.generatePublic(keySpec);
  } catch (Exception e) {
      throw new Exception("公鑰創(chuàng)建失敗", e);
  }
  }

• 私鑰字符串生成私鑰

  public static RSAPrivateKey createPrivateKey(String privateKeyValue) throws Exception {
  try {
      byte[] buffer = javax.xml.bind.DatatypeConverter.parseBase64Binary(privateKeyValue);
      PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
      KeyFactory keyFactory = KeyFactory.getInstance("RSA");
      return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
  } catch (Exception e) {
      throw new Exception("私鑰創(chuàng)建失敗", e);
  }
  }

3、加密和解密

• 公鑰加密

  public static String encrypt(RSAPublicKey publicKey, byte[] clearData) throws Exception {
  if (publicKey == null) {
      throw new Exception("加密公鑰為空, 無法加密");
  }
  try {
      Cipher cipher = Cipher.getInstance("RSA") ;
      cipher.init(Cipher.ENCRYPT_MODE, publicKey);
      byte[] output = cipher.doFinal(clearData);
      return printBase64Binary(output);
  } catch (Exception e) {
      throw new Exception("公鑰加密失敗",e);
  }
  }

• 私鑰解密

  public static String decrypt(RSAPrivateKey privateKey, byte[] cipherData) throws Exception {
  if (privateKey == null) {
      throw new Exception("解密私鑰為空, 無法解密");
  }
  try {
      Cipher cipher = Cipher.getInstance("RSA") ;
      cipher.init(Cipher.DECRYPT_MODE, privateKey);
      byte[] output = cipher.doFinal(cipherData);
      return new String(output);
  } catch (BadPaddingException e) {
      throw new Exception("私鑰解密失敗",e);
  }
  }

4、簽名和驗簽

• 私鑰簽名

  public static String sign (String signData, PrivateKey privateKey) throws Exception {
  byte[] keyBytes = privateKey.getEncoded();
  PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
  KeyFactory keyFactory = KeyFactory.getInstance("RSA");
  PrivateKey key = keyFactory.generatePrivate(keySpec);
  Signature signature = Signature.getInstance("MD5withRSA");
  signature.initSign(key);
  signature.update(signData.getBytes());
  return printBase64Binary(signature.sign());
  }

• 公鑰驗簽

  public static boolean verify(String srcData, PublicKey publicKey, String sign) throws Exception {
  byte[] keyBytes = publicKey.getEncoded();
  X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
  KeyFactory keyFactory = KeyFactory.getInstance("RSA");
  PublicKey key = keyFactory.generatePublic(keySpec);
  Signature signature = Signature.getInstance("MD5withRSA");
  signature.initVerify(key);
  signature.update(srcData.getBytes());
  return signature.verify(parseBase64Binary(sign));
  }

5、編碼和解碼

/**
 * 字節(jié)數(shù)組轉(zhuǎn)字符
 */
public static String printBase64Binary(byte[] bytes) {
    return DatatypeConverter.printBase64Binary(bytes);
}
/**
 * 字符轉(zhuǎn)字節(jié)數(shù)組
 */
public static byte[] parseBase64Binary(String value) {
    return DatatypeConverter.parseBase64Binary(value);
}

6、測試代碼塊

• 密鑰生成測試

  public static void testCreateKey () throws Exception {
  HashMap<String, String> map = RsaCryptUtil.getTheKeys();
  String privateKeyStr=map.get("privateKey");
  String publicKeyStr=map.get("publicKey");
  System.out.println("私鑰："+privateKeyStr);
  System.out.println("公鑰："+publicKeyStr);
  //消息發(fā)送方
  String originData="cicada-smile";
  System.out.println("原文："+originData);
  String encryptData = RsaCryptUtil.encrypt(RsaCryptUtil.createPublicKey(publicKeyStr),
                                            originData.getBytes());
  System.out.println("加密："+encryptData);
  //消息接收方
  String decryptData=RsaCryptUtil.decrypt(RsaCryptUtil.createPrivateKey(privateKeyStr),
                                          RsaCryptUtil.parseBase64Binary(encryptData));
  System.out.println("解密："+decryptData);
  }

• 密鑰讀取測試

  public static void testReadKey () throws Exception {
  String value = getKey("rsaKey/public.key");
  System.out.println(value);
  String privateKeyStr = getKey(RsaCryptUtil.PRI_KEY) ;
  String publicKeyStr = getKey(RsaCryptUtil.PUB_KEY) ;
  //消息發(fā)送方
  String originData="cicada-smile";
  System.out.println("原文："+originData);
  String encryptData = RsaCryptUtil.encrypt(RsaCryptUtil.createPublicKey(publicKeyStr),
                                            originData.getBytes());
  System.out.println("加密："+encryptData);
  //消息接收方
  String decryptData=RsaCryptUtil.decrypt(RsaCryptUtil.createPrivateKey(privateKeyStr),
                                          RsaCryptUtil.parseBase64Binary(encryptData));
  System.out.println("解密："+decryptData);
  }

• 簽名驗簽測試

  public static void testSignVerify () throws Exception {
  String signData = "cicada-smile" ;
  String privateKeyStr = getKey(RsaCryptUtil.PRI_KEY) ;
  String publicKeyStr = getKey(RsaCryptUtil.PUB_KEY) ;
  String signValue = sign(signData,RsaCryptUtil.createPrivateKey(privateKeyStr)) ;
  boolean flag = verify(signData,RsaCryptUtil.createPublicKey(publicKeyStr),signValue);
  System.out.println("原文:"+signData);
  System.out.println("簽名:"+signValue);
  System.out.println("驗簽:"+flag);
  }

四、源代碼地址

GitHub·地址
https://github.com/cicadasmile
GitEE·地址
https://gitee.com/cicadasmile