几种JAVA加密算法

1. MD5加密,常用于加密用户名密码,当用户验证时。

   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,与MD5相似的用法,只是两者的算法不同。

   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加密允许解密。常用于文本内容的加密。

    import java.security.KeyPair;
  import java.security.KeyPairGenerator;
  import java.security.interfaces.RSAPrivateKey;
  import java.security.interfaces.RSAPublicKey;
  import javax.crypto.Cipher;   /** *//**
  * RSAEncrypt
  *
  * @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;
  }
  }

原文:http://www.cnblogs.com/mycodelife/archive/2009/04/22/1441624.html

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