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;
}
}
--转自