/*********************************************************************************
 *      Copyright:  (C) 2018 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  crypto.c
 *    Description:  This file is LingYun crypto library 
 *                 
 *        Version:  1.0.0(2018年12月20日)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "2018年12月20日 11时56分04秒"
 *                 
 ********************************************************************************/
#include <string.h>

int encrypt(char *plaintext, char *ciphertext, int size)
{
    int       i;

    if( size < strlen(plaintext) )
    {
        return -1;
    }

    for(i=0; i<strlen(plaintext); i++)
    {
        ciphertext[i] = plaintext[i]+3;
    }

    return 0;
}

int decrypt(char *ciphertext, char *plaintext, int size)
{
    int      i;

    if( size < strlen(ciphertext) )
    {
        return -1;
    }

    for(i=0; i<strlen(ciphertext); i++)
    {
        plaintext[i] = ciphertext[i]-3;
    }

    return 0;
}