（手工）base64加密解密

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加密算法

    public static string Base64Encrypt(string saltStr,string sourceStr)
        {
            string targetStr = string.Empty;
            sourceStr = saltStr + sourceStr;
            if (sourceStr.Length % 3 == 1)
            {sourceStr = sourceStr + "=" + "="; }
            else if(sourceStr.Length%3==2)
            { sourceStr = sourceStr + "="; }

            byte[] sourceByte = UnicodeEncoding.Unicode.GetBytes(sourceStr);  
            int count = sourceByte.Length;                              

            List<byte> by = new List<byte>();
            for (int current = 0; current < count; current++)
            {
                by.AddRange(toBit(sourceByte[current]));
            }
            byte[] bit8 = new byte[8];     
            byte[] bit24 = new byte[24];    //temp
            int i = 0;
            int j = 0;
            List<byte> targetByte = new List<byte>();
            foreach (byte b in by)
            {
                bit24[i] = b;
                if (i == 23)
                {
                    bit24[i] = b;
                    targetByte.AddRange(bit24tobit32(bit24));
                    i =-1;
                }
                i++;
            }

            i = 0;
            byte[] byy = new byte[targetByte.Count / 8];
            foreach (byte b in targetByte)
            {
                bit8[i] = b;
                if (i == 7)
                {
                    bit8[7] = b;
                    byy[j++] = (byte)toNum(bit8);
                    i = -1;
                }
                i++;
            }
            targetStr = UnicodeEncoding.Unicode.GetString(byy);
            return targetStr;
        }

解密算法

public static string Base64Unencrypt(string saltStr,string sourceStr)
        {
            string targetStr = string.Empty;
            byte[] temp = UnicodeEncoding.Unicode.GetBytes(sourceStr);  //转byte
            byte[] sourceByte=new  byte[0];
            List<byte> targetByte = new List<byte>();
            byte[] bit8 = new byte[8];
            int i = 0;
            int j = 0;
            for (int m = 0; m < temp.Length; m++)
            {
                sourceByte = sourceByte.Concat(toBit(temp[m])).ToArray(); 
            }
            foreach (byte b in sourceByte)
            {
                bit8[i] = b;
                if (i == 7)
                {
                    bit8[i] = b;
                    targetByte.AddRange(bit8.ToList<byte>().GetRange(2,6));
                    i = -1;
                }
                i++;
            }
            i = 0;
            byte[] byy=new  byte[targetByte.Count/8];
            foreach (byte b in targetByte)
            {
                bit8[i] = b;
                if (i == 7)
                {
                    bit8[7] = b;
                    byy[j++] = (byte)toNum(bit8);
                    i = -1;
                }
                i++;
            }
            targetStr = UnicodeEncoding.Unicode.GetString(byy);
            targetStr = targetStr.TrimEnd(‘=‘);
            targetStr = targetStr.Substring(saltStr.Length - 1);
            return targetStr;
        }

所需函数

 public static byte[] bit24tobit32(byte[] bit24)
        {
            byte[] bit32 = new byte[32];
            int j = -1;
            for (int i = 0; i < 24; i++)
            {
                if (i % 6 == 0)
                {
                    bit32[++j] = 0;
                    bit32[++j] = 0;
                    bit32[++j] = bit24[i];
                }
                else
                {
                    bit32[++j] = bit24[i];
                }
            }
            return bit32;
        }
        public static int toNum(byte[] by)
        {
            int num = 0;
            int i = 7;
            foreach (byte b in by)
            {
                if (b != 0)
                {
                    num = num + (int)Math.Pow(2,i);
                }
                    i--;
            }
            return num;
        }

        public static byte[] toBit(byte num1)
        {
            byte[] bit = new byte[8];
            int num = Convert.ToInt32(num1);
            if (num > -1 || num < 128)
            {
                for (int i = 0; i < 8; i++)
                { bit[7 - i] = (byte)((num - ((num = num >> 1) << 1))); }
            }
            else
            { throw new IndexOutOfRangeException("超出范围"); }
            return bit;
        }

测试代码

            Console.WriteLine("输入需base64加密字符串");
            string saltStr = string.Empty;
            string sourceStr = string.Empty;
            Console.WriteLine("输入加盐字符串");
            saltStr = Console.ReadLine();
            Console.WriteLine("输入需base64加密字符串");
            sourceStr = Console.ReadLine();
            string encryptStr = Base64Encrypt(saltStr, sourceStr);
            Console.WriteLine("加密后的字符串"+encryptStr);

            Console.WriteLine("输入加盐字符串");
            saltStr = Console.ReadLine();
            Console.WriteLine("输入需base64解密字符串，字符乱糟糟的不输了");
            //sourceStr = Console.ReadLine();
            string unEncryptStr = Base64Unencrypt(saltStr, encryptStr);
            Console.WriteLine("加密后的字符串" + unEncryptStr);

测试结果

（手工）base64加密解密

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原文地址：http://my.oschina.net/hunjixin/blog/508710