C#大量兑换码的生成与验证方案

翻译自：https://blog.youkuaiyun.com/zgjllf1011/article/details/79297512

作者代码是Java代码，然后自己翻译成C#代码。实现原理原作者博客中有详细介绍；

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApp1
{
    class Program
    {
        static String stringtable = "abcdefghijkmnpqrstuvwxyz23456789";
        static String password = "dak3le2";

        //从byte转为字符表索引所需要的位数
        static int convertByteCount = 5;
        static void Main(string[] args)
        {
            List<string> list = CreateCode((byte)10, 10000, 12, password);
            //验证是否有重复数据
            var query = from l in list group l by new { l} into g
                        select new
                        {
                            RepeatNameCount = g.Count()
                        };
            int count = 0;
            foreach (var item in query)
            {
                if (item.RepeatNameCount > 1)
                {
                    count++;
                }
            }
           
            Console.WriteLine("重复数据数量："+ count);
            Console.Read();
        }
        public static List<string> CreateCode(byte groupid, int codecount, int codelength, String password)
        {
            List<string> list = new List<string>();
            //8位的数据总长度
            int fullcodelength = codelength * convertByteCount / 8;
            //随机码对时间和id同时做异或处理
            //类型1，id4，随机码n,校验码1 
            int randcount = fullcodelength - 6;//随机码有多少个

            //如果随机码小于0 不生成
            if (randcount <= 0)
            {
                return null;
            }
            for (int i = 0; i < codecount; i++)
            {
                //这里使用i作为code的id
                //生成n位随机码
                byte[] randbytes = new byte[randcount];
                for (int j = 0; j < randcount; j++)
                {
                    Random dom = new Random();
                    double param = dom.Next(1, 10) / 10.0;
                    randbytes[j] = (byte)(param * Byte.MaxValue);
                }

                //存储所有数据
                ByteHapper byteHapper = ByteHapper.CreateBytes(fullcodelength);
                byteHapper.AppendNumber(groupid).AppendNumber(i).AppendBytes(randbytes);

                //计算校验码 这里使用所有数据相加的总和与byte.max 取余
                byte verify = (byte)(byteHapper.GetSum() % Byte.MaxValue);
                byteHapper.AppendNumber(verify);

                //使用随机码与时间和ID进行异或
                for (int j = 0; j < 5; j++)
                {
                    byteHapper.bytes[j] = (byte)(byteHapper.bytes[j] ^ (byteHapper.bytes[5 + j % randcount]));
                }

                //使用密码与所有数据进行异或来加密数据
                byte[] passwordbytes = System.Text.Encoding.ASCII.GetBytes(password);
                for (int j = 0; j < byteHapper.bytes.Length; j++)
                {
                    byteHapper.bytes[j] = (byte)(byteHapper.bytes[j] ^ passwordbytes[j % passwordbytes.Length]);
                }

                //这里存储最终的数据
                byte[] bytes = new byte[codelength];

                //按6位一组复制给最终数组
                for (int j = 0; j < byteHapper.bytes.Length; j++)
                {
                    for (int k = 0; k < 8; k++)
                    {
                        int sourceindex = j * 8 + k;
                        int targetindex_x = sourceindex / convertByteCount;
                        int targetindex_y = sourceindex % convertByteCount;
                        byte placeval = (byte)Math.Pow(2, k);
                        byte val = (byte)((byteHapper.bytes[j] & placeval) == placeval ? 1 : 0);
                        //复制每一个bit
                        bytes[targetindex_x] = (byte)(bytes[targetindex_x] | (val << targetindex_y));
                    }
                }

                StringBuilder result = new StringBuilder();
                //编辑最终数组生成字符串
                for (int j = 0; j < bytes.Length; j++)
                {
                    result.Append(stringtable.Substring(bytes[j],1));
                }
                
                Console.WriteLine(result.ToString());
                list.Add(result.ToString());
            }
            return list;
        }
    }
   
    public class ByteHapper
    {
        //原始数组
        public byte[] bytes { get; set; }
        //记录当前写入到多少位
        int index;

        private ByteHapper(int capacity)
        {
            bytes = new byte[capacity];
            index = 0;
        }

        public static ByteHapper CreateBytes(int capacity)
        {
            ByteHapper byteHapper = new ByteHapper(capacity);
            return byteHapper;
        }

        //向数组中追加内容
        public ByteHapper AppendNumber(long val)
        {
            byte[] arr = Number2byte(val);
            AppendBytes(arr);
            return this;
        }
        public ByteHapper AppendNumber(int val)
        {
            byte[] arr = Number2byte(val);
            AppendBytes(arr);
            return this;
        }
        public ByteHapper AppendNumber(short val)
        {
            byte[] arr = Number2byte(val);
            AppendBytes(arr);
            return this;
        }
        public ByteHapper AppendNumber(byte val)
        {
            byte[] arr = new byte[] { val };
            AppendBytes(arr);
            return this;
        }

        /**
         * 获取数据的总和
         * @return
         */
        public int GetSum()
        {
            int ret = 0;
            for (int i = 0; i < bytes.Length; i++)
            {
                ret += bytes[i];
            }
            return ret;
        }

        //追加byte数组
        public ByteHapper AppendBytes(byte[] arr)
        {

            for (byte i = 0; i < arr.Length; i++)
            {
                bytes[index + i] = arr[i];
            }

            index += arr.Length;
            return this;
        }

        /**
         * 将数字转换为byte数组
         */
        public static byte[] Number2byte(long val)
        {

            byte[] arr = new byte[]{
                (byte) ((val >> 56) & 0xFF),
                (byte) ((val >> 48) & 0xFF),
                (byte) ((val >> 40) & 0xFF),
                (byte) ((val >> 32) & 0xFF),
                (byte) ((val >> 24) & 0xFF),
                (byte) ((val >> 16) & 0xFF),
                (byte) ((val >> 8) & 0xFF),
                (byte) (val & 0xFF)
        };

            return arr;
        }
        public static byte[] Number2byte(int val)
        {

            byte[] arr = new byte[]{
                (byte) ((val >> 24) & 0xFF),
                (byte) ((val >> 16) & 0xFF),
                (byte) ((val >> 8) & 0xFF),
                (byte) (val & 0xFF)
        };

            return arr;
        }
        public static byte[] Number2byte(short val)
        {

            byte[] arr = new byte[]{
                (byte) ((val >> 8) & 0xFF),
                (byte) (val & 0xFF)
        };

            return arr;
        }
    }

}