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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;
/** *//**
* <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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