• JAVA实现RSA算法


    实现一对密钥对整个项目所有加密解密文件都适用的方法,采用先生成一对密钥.保存到xml文件中,以后获得私匙和公钥只需要从xml文件中取得就可以了.

      /**

      * 把成生的一对密钥保存到RSAKey.xml文件中

      */

      public void saveRSAKey() {

      try {

      SecureRandom sr = new SecureRandom();

      KeyPairGenerator kg = KeyPairGenerator.getInstance(\"RSA\",

      new org.bouncycastle.jce.provider.BouncyCastleProvider());

      //注意密钥大小最好为1024,否则解密会有乱码情况.

      kg.initialize(1024, sr);

      FileOutputStream fos = new FileOutputStream(\"C:/RSAKey.xml\");

      ObjectOutputStream oos = new ObjectOutputStream(fos);

      //生成密钥

      oos.writeObject(kg.generateKeyPair());

      oos.close();

      } catch (Exception e) {

      e.printStackTrace();

      }

      }

      注意:需要从http://www.bouncycastle.org下载bcprov-jdk14-137.jar包.

      获取密钥方法如下:

      /**

      * 获得RSA加密的密钥。

      * @return KeyPair返回对称密钥

      */

      public static KeyPair getKeyPair() {

      //产生新密钥对

      KeyPair kp;

      try {

      String fileName = \"conf/RASKey.xml\";

      InputStream is = FileUtils.class.getClassLoader()

      .getResourceAsStream(fileName);

      ObjectInputStream oos = new ObjectInputStream(is);

      kp = (KeyPair) oos.readObject();

      oos.close();

      } catch (Exception e) {

      throw new EprasRuntimeException(\"读取加密文件出错.\", e);

      }

      return kp;

      }

      文件采用RSA算法加密文件

      /**

      * 文件file进行加密并保存目标文件destFile中

      * @param srcFileName

      * 要加密的文件 如c:/test/srcFile.txt

      * @param destFileName

      * 加密后存放的文件名 如c:/加密后文件.txt

      */

      public static void encryptFile(String srcFileName,

      String destFileName) throws Exception {

      OutputStream outputWriter = null;

      InputStream inputReader = null;

      try {

      Cipher cipher = Cipher.getInstance(\"RSA/ECB/PKCS1Padding\",

      new org.bouncycastle.jce.provider.BouncyCastleProvider());

      byte[] buf = new byte[100];

      int bufl;

      cipher.init(Cipher.ENCRYPT_MODE, getKeyPair().getPublic());

      outputWriter = new FileOutputStream(destFileName);

      inputReader = new FileInputStream(srcFileName);

      while ((bufl = inputReader.read(buf)) != -1) {

      byte[] encText = null;

      byte[] newArr = null;

      if (buf.length == bufl) {

      newArr = buf;

      } else {

      newArr = new byte[bufl];

      for (int i = 0; i < bufl; i++) {

      newArr = (byte) buf;

      }

      }

      encText = cipher.doFinal(newArr);

      outputWriter.write(encText);

      }

      outputWriter.flush();

      } catch (Exception e) {

      throw e;

      } finally {

      try {

      if (outputWriter != null) {

      outputWriter.close();

      }

      if (inputReader != null) {

      inputReader.close();

      }

      } catch (Exception e) {

      }

      }

      }

      文件采用RSA算法解密文件

      /**

      * 文件file进行加密并保存目标文件destFile中

      * @param srcFileName

      * 已加密的文件 如c:/加密后文件.txt

      * @param destFileName

      * 解密后存放的文件名 如c:/ test/解密后文件.txt

      */

      public static void decryptFile(String srcFileName,

      String destFileName) throws Exception {

      OutputStream outputWriter = null;

      InputStream inputReader = null;

      try {

      Cipher cipher = Cipher.getInstance(\"RSA/ECB/PKCS1Padding\",

      new org.bouncycastle.jce.provider.BouncyCastleProvider());

      byte[] buf = new byte[128];

      int bufl;

      cipher.init(Cipher.DECRYPT_MODE, getKeyPair().getPrivate());

      outputWriter = new FileOutputStream(destFileName);

      inputReader = new FileInputStream(srcFileName);

      while ((bufl = inputReader.read(buf)) != -1) {

      byte[] encText = null;

      byte[] newArr = null;

      if (buf.length == bufl) {

      newArr = buf;

      } else {

      newArr = new byte[bufl];

      for (int i = 0; i < bufl; i++) {

      newArr = (byte) buf;

      }

      }

      encText = cipher.doFinal(newArr);

      outputWriter.write(encText);

      }

      outputWriter.flush();

      } catch (Exception e) {

      throw e;

      } finally {

      try {

      if (outputWriter != null) {

      outputWriter.close();

      }

      if (inputReader != null) {

      inputReader.close();

      }

      } catch (Exception e) {

      }

      }

      }

      如果对于大文件加密采用RSA算法执行速度要非常非常慢。

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  • 原文地址:https://www.cnblogs.com/langtianya/p/2886346.html
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