java RSA加密類

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import javax.crypto.Cipher;

/**

RSA加密類
*/
public class RSAEncrypt {
public static void main(String[] args) {

 try {
     RSAEncrypt encrypt = new RSAEncrypt();
     String encryptText = "12345678";
     KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
     keyPairGen.initialize(1024);
     KeyPair keyPair = keyPairGen.generateKeyPair();
     // Generate keys
     RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 私鑰
     RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); // 公鑰
     byte[] e = encrypt.encrypt(publicKey, encryptText.getBytes());
     byte[] de = encrypt.decrypt(privateKey, e);
     System.out.println(encrypt.bytesToString(e));
     System.out.println();

     System.out.println(encrypt.bytesToString(de));
 } catch (Exception e) {
     e.printStackTrace();
 }

}
/**

byte數組轉為string

@param encrytpByte
@return
*/
protected String bytesToString(byte[] encrytpByte) {
 String result = "";
 for (Byte bytes : encrytpByte) {

 result += (char) bytes.intValue();

}
 return result;
}
/**

加密方法

@param publicKey
@param obj
@return
*/
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;
}
/**

解密方法

@param privateKey
@param obj
@return
*/
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;
}
}</pre>