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 程式師世界 >> 編程語言 >> JAVA編程 >> 關於JAVA >> Java中常用的加密算法MD5,SHA,RSA的應用

Java中常用的加密算法MD5,SHA,RSA的應用

編輯:關於JAVA

1. MD5加密,常用於加密用戶名密碼,當用戶驗證時。

protected byte[] encrypt(byte[] obj) ...{
  try ...{
    MessageDigest md5 = MessageDigest.getInstance("MD5");
      md5.update(obj);
    return md5.digest();
  } catch (NoSuchAlgorithmException e) ...{
    e.printStackTrace();
  }
}

2. SHA加密,與MD5相似的用法,只是兩者的算法不同。

protected byte[] encrypt(byte[] obj) ...{
  try ...{
    MessageDigest sha = MessageDigest.getInstance("SHA");
      sha.update(obj);
    return sha.digest();
  } catch (NoSuchAlgorithmException e) ...{
    e.printStackTrace();
  }
}

3. RSA加密,RAS加密允許解密。常用於文本內容的加密。

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import javax.crypto.Cipher;
/** *//**
* <b>RSAEncrypt</b>
* <p>
* @author maqujun
* @see
*/
public class RSAEncrypt ...{
  /** *//**
* Main method for RSAEncrypt.
   * @param args
   */
  public static void main(String[] args) ...{
    try ...{
      RSAEncrypt encrypt = new RSAEncrypt();

      String encryptText = "encryptText";
      KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
      keyPairGen.initialize(1024);
      KeyPair keyPair = keyPairGen.generateKeyPair();
      // Generate keys
      RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
      RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

      byte[] e = encrypt.encrypt(publicKey, encryptText.getBytes());
      byte[] de = encrypt.decrypt(privateKey,e);
      System.out.println(encrypt.bytesToString(e));
      System.out.println(encrypt.bytesToString(de));
    } catch (Exception e) ...{
      e.printStackTrace();
    }
  }

/** *//**
   * Change byte array to String.
   * @return byte[]
   */
  protected String bytesToString(byte[] encrytpByte) ...{
    String result = "";
    for (Byte bytes : encrytpByte) ...{
      result += (char) bytes.intValue();
    }
    return result;
  }

/** *//**
   * Encrypt String.
   * @return byte[]
   */
  protected byte[] encrypt(RSAPublicKey publicKey, byte[] obj) ...{
    if (publicKey != null) ...{
      try ...{
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(obj);
      } catch (Exception e) ...{
        e.printStackTrace();
      }
    }
    return null;
  }
  /** *//**
   * Basic decrypt method
   * @return byte[]
   */
  protected byte[] decrypt(RSAPrivateKey privateKey, byte[] obj) ...{
    if (privateKey != null) ...{
        try ...{
          Cipher cipher = Cipher.getInstance("RSA");
          cipher.init(Cipher.DECRYPT_MODE, privateKey);
          return cipher.doFinal(obj);
        } catch (Exception e) ...{
          e.printStackTrace();
        }
      }

    return null;
  }
}

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