新浪微博、qq等javascript rsa密码加密c#实现。

可用在新浪微博最新版的登录、qq注册、qq微博注册过程中的密码加密。

按js实现翻译过来的，为了对比方便，保留着js的命名。大数计算类BigInteger是c# 4.0才提供的，如果不想用这么高的版本，这里有个开源的实现：http://www.codeproject.com/csharp/biginteger.asp

 

public class JSRSAUtil    

    {   

        private static Random rand = new Random();



        private BigInteger n = null;

        private BigInteger e = null;



        private BigInteger pkcs1pad2(string a, int b)

        {

            if (b < a.Length + 11)

            {

                throw new Exception("Message too long for RSA");

            }



            byte[] c = new byte[b];

            int d = a.Length - 1;

            while (d >= 0 && b > 0)

            {

                int e = (int)a[d--];

                if (e < 128)

                {

                    c[--b] = Convert.ToByte(e);

                }

                else if ((e > 127) && (e < 2048))

                {

                    c[--b] = Convert.ToByte(((e & 63) | 128));

                    c[--b] = Convert.ToByte((e >> 6) | 192);

                }

                else

                {

                    c[--b] = Convert.ToByte((e & 63) | 128);

                    c[--b] = Convert.ToByte(((e >> 6) & 63) | 128);

                    c[--b] = Convert.ToByte(((e >> 12) | 224));

                }

            }



            c[--b] = Convert.ToByte(0);



            byte[] temp = new byte[1];



            while (b > 2)

            {

                temp[0] = Convert.ToByte(0);

                while (temp[0] == 0)

                    rand.NextBytes(temp);

                c[--b] = temp[0];

            }



            c[--b] = 2;

            c[--b] = 0;



            return new BigInteger(c);

        }



        public void RSASetPublic(string a, string b)

        {

            if (string.IsNullOrEmpty(a) || string.IsNullOrEmpty(b))

            {

                throw new Exception("Message too long for RSA");

            }



            n = new BigInteger(a, 16);

            e = new BigInteger(b, 16);

        }



        private BigInteger RSADoPublic(BigInteger x)

        {

            return x.modPow(e, n);

        }



        public string RSAEncrypt(string a)

        {

            BigInteger tmp = pkcs1pad2(a, (n.bitCount() + 7) >> 3);



            tmp = RSADoPublic(tmp);



            string result = tmp.ToHexString();

            return 0 == (result.Length & 1) ? result : "0" + result;

        }

    }

转自：http://pwg17.github.com/2012/12/16/weibo-qq-rsa-csharp/