RSA 加密

        public static string RsaEncrypt(string publickey, string content)
        {
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            byte[] cipherbytes;
            rsa.FromXmlString(publickey);
            cipherbytes = rsa.Encrypt(Encoding.UTF8.GetBytes(content), false);
            return Convert.ToBase64String(cipherbytes);
        }
        public static string RSADecrypt(string privatekey, string content)
        {
            var rsa = new RSACryptoServiceProvider();
            byte[] cipherbytes;
            rsa.FromXmlString(privatekey);
            cipherbytes = rsa.Decrypt(Convert.FromBase64String(content), false);
            return Encoding.UTF8.GetString(cipherbytes);
        } 

生成key：

            string _publicKey;
            string _privateKey;
            RSACryptoServiceProvider _rsaService;
            _rsaService = new RSACryptoServiceProvider();
            _publicKey = _rsaService.ToXmlString(false);
            _privateKey = _rsaService.ToXmlString(true);

可java一起用：

public static string RSAEncryptSpilt(string publickey, string content)
        {
            //公钥
            //publickey = _publickey; 
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();

            byte[] byteArray = Encoding.UTF8.GetBytes(content);
            //byte[] byteArray = System.Text.Encoding.Default.GetBytes(content);
            content = Convert.ToBase64String(byteArray);
            rsa.FromXmlString(publickey);
            byte[] OriginalData = Convert.FromBase64String(content);

            if (OriginalData == null || OriginalData.Length <= 0)
            {
                throw new NotSupportedException();
            }
            if (rsa == null)
            {
                throw new ArgumentNullException();
            }


            int bufferSize = (rsa.KeySize / 8) - 37;
            byte[] buffer = new byte[bufferSize];
        
            using (MemoryStream input = new MemoryStream(OriginalData))
            using (MemoryStream ouput = new MemoryStream())
            {
                while (true)
                {
                    int readLine = input.Read(buffer, 0, bufferSize);
                    if (readLine <= 0)
                    {
                        break;
                    }
                    byte[] temp = new byte[readLine];
                    Array.Copy(buffer, 0, temp, 0, readLine);
                    byte[] encrypt = rsa.Encrypt(temp, false);
                    ouput.Write(encrypt, 0, encrypt.Length);
                }
                return Convert.ToBase64String(ouput.ToArray());
            }
        }

        public static string RSADecryptSpilt(string privatekey, string content)
        {
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();

            byte[] EncryptDada = Convert.FromBase64String(content);

            if (EncryptDada == null || EncryptDada.Length <= 0)
            {
                throw new NotSupportedException();
            }
            //私钥
            //privatekey = _privatekey; 

            rsa.FromXmlString(privatekey);
            int keySize = rsa.KeySize / 8;
            byte[] buffer = new byte[keySize];

            using (MemoryStream input = new MemoryStream(EncryptDada))
            using (MemoryStream output = new MemoryStream())
            {
                while (true)
                {
                    int readLine = input.Read(buffer, 0, keySize);
                    if (readLine <= 0)
                    {
                        break;
                    }
                    byte[] temp = new byte[readLine];
                    Array.Copy(buffer, 0, temp, 0, readLine);
                    byte[] decrypt = rsa.Decrypt(temp, false);
                    output.Write(decrypt, 0, decrypt.Length);
                }
                return Encoding.UTF8.GetString(output.ToArray());
            }

        }