RSA 数字签名算法（.net版）

直接上代码，不BB

    public class RSASign
    {
        public static string RSASignature(string data, string privateKeyPem, string charset, bool keyFromFile, string signType)
        {

            byte[] signatureBytes = null;
            try
            {
                RSACryptoServiceProvider rsaCsp = null;
                if (keyFromFile)
                {//文件读取
                    rsaCsp = LoadCertificateFile(privateKeyPem, signType);
                }
                else
                {
                    //字符串获取
                    rsaCsp = LoadCertificateString(privateKeyPem, signType);
                }

                byte[] dataBytes = null;
                if (string.IsNullOrEmpty(charset))
                {
                    dataBytes = Encoding.UTF8.GetBytes(data);
                }
                else
                {
                    dataBytes = Encoding.GetEncoding(charset).GetBytes(data);
                }
                if (null == rsaCsp)
                {
                    throw new Exception("您使用的私钥格式错误" + ",charset = " + charset);
                }
                if ("RSA2".Equals(signType))
                {

                    signatureBytes = rsaCsp.SignData(dataBytes, "SHA256");

                }
                else
                {
                    signatureBytes = rsaCsp.SignData(dataBytes, "SHA1");
                }

            }
            catch (Exception ex)
            {
                throw new Exception("您使用的私钥格式错误" + ",charset = " + charset);
            }
            return Convert.ToBase64String(signatureBytes);
        }

        private static RSACryptoServiceProvider LoadCertificateFile(string filename, string signType)
        {
            using (System.IO.FileStream fs = System.IO.File.OpenRead(filename))
            {
                byte[] data = new byte[fs.Length];
                byte[] res = null;
                fs.Read(data, 0, data.Length);
                if (data[0] != 0x30)
                {
                    res = GetPem("RSA PRIVATE KEY", data);
                }
                try
                {
                    RSACryptoServiceProvider rsa = DecodeRSAPrivateKey(res, signType);
                    return rsa;
                }
                catch (Exception ex)
                {
                }
                return null;
            }
        }
        private static byte[] GetPem(string type, byte[] data)
        {
            string pem = Encoding.UTF8.GetString(data);
            string header = String.Format("-----BEGIN {0}-----\n", type);
            string footer = String.Format("-----END {0}-----", type);
            int start = pem.IndexOf(header) + header.Length;
            int end = pem.IndexOf(footer, start);
            string base64 = pem.Substring(start, (end - start));

            return Convert.FromBase64String(base64);
        }
        private static RSACryptoServiceProvider LoadCertificateString(string strKey, string signType)
        {
            byte[] data = null;
            data = Convert.FromBase64String(strKey);
            try
            {
                RSACryptoServiceProvider rsa = DecodeRSAPrivateKey(data, signType);
                return rsa;
            }
            catch
            {
            }
            return null;
        }

        private static RSACryptoServiceProvider DecodeRSAPrivateKey(byte[] privkey, string signType)
        {
            byte[] MODULUS, E, D, P, Q, DP, DQ, IQ;

            MemoryStream mem = new MemoryStream(privkey);
            BinaryReader binr = new BinaryReader(mem);  
            byte bt = 0;
            ushort twobytes = 0;
            int elems = 0;
            try
            {
                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8130) 
                    binr.ReadByte();  
                else if (twobytes == 0x8230)
                    binr.ReadInt16(); 
                else
                    return null;

                twobytes = binr.ReadUInt16();
                if (twobytes != 0x0102)
                    return null;
                bt = binr.ReadByte();
                if (bt != 0x00)
                    return null;
                elems = GetIntegerSize(binr);
                MODULUS = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                E = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                D = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                P = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                Q = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                DP = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                DQ = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                IQ = binr.ReadBytes(elems);


                CspParameters CspParameters = new CspParameters();
                CspParameters.Flags = CspProviderFlags.UseMachineKeyStore;

                int bitLen = 1024;
                if ("RSA2".Equals(signType))
                {
                    bitLen = 2048;
                }

                RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(bitLen, CspParameters);
                RSAParameters RSAparams = new RSAParameters();
                RSAparams.Modulus = MODULUS;
                RSAparams.Exponent = E;
                RSAparams.D = D;
                RSAparams.P = P;
                RSAparams.Q = Q;
                RSAparams.DP = DP;
                RSAparams.DQ = DQ;
                RSAparams.InverseQ = IQ;
                RSA.ImportParameters(RSAparams);
                return RSA;
            }
            catch(Exception ex) 
            {
                return null;
            }
            finally
            {
                binr.Close();
            }
        }

        private static int GetIntegerSize(BinaryReader binr)
        {
            byte bt = 0;
            byte lowbyte = 0x00;
            byte highbyte = 0x00;
            int count = 0;
            bt = binr.ReadByte();
            if (bt != 0x02)        
                return 0;
            bt = binr.ReadByte();

            if (bt == 0x81)
                count = binr.ReadByte();
            else
                if (bt == 0x82)
            {
                highbyte = binr.ReadByte(); 
                lowbyte = binr.ReadByte();
                byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };
                count = BitConverter.ToInt32(modint, 0);
            }
            else
            {
                count = bt;  
            }

            while (binr.ReadByte() == 0x00)
            {    
                count -= 1;
            }
            binr.BaseStream.Seek(-1, SeekOrigin.Current);    
            return count;
        }

    }