.net中RSA加密解密

1、产生密钥：

private static void CreateKey()
        {
            using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
            {
                string publicKey = rsa.ToXmlString(false); // 公钥
                string privateKey = rsa.ToXmlString(true); // 私钥               
            }
        }

这里产生的密钥是xml格式的，这也是.net的rsa的密钥格式。但有时候在.net项目中，我们只有java格式的密钥，具体的来说密钥就是一个字符串，这时候需要将其转换为xml格式的。

//公钥格式的转换
public static string RsaPublicKeyToXml(string publicKey)
        {
            try
            {
                if (string.IsNullOrWhiteSpace(publicKey))
                    return "";
                if (publicKey.Contains("<RSAKeyValue>"))
                    return publicKey;
                RsaKeyParameters publicKeyParam;
                //尝试进行java格式的密钥读取
                try
                {
                    publicKeyParam = (RsaKeyParameters)PublicKeyFactory.CreateKey(Convert.FromBase64String(publicKey));
                }
                catch
                {
                    publicKeyParam = null;
                }
                //非java格式密钥进行pem格式的密钥读取
                if (publicKeyParam == null)
                {
                    try
                    {
                        var pemKey = publicKey;
                        if (!pemKey.Contains("BEGIN RSA PRIVATE KEY"))
                        {
                            pemKey = @"-----BEGIN RSA PRIVATE KEY-----
                           " + publicKey + @"
                           -----END RSA PRIVATE KEY-----";
                        }
                        var array = Encoding.ASCII.GetBytes(pemKey);
                        var stream = new MemoryStream(array);
                        var reader = new StreamReader(stream);
                        var pemReader = new Org.BouncyCastle.OpenSsl.PemReader(reader);
                        publicKeyParam = (RsaKeyParameters)pemReader.ReadObject();
                    }
                    catch
                    {
                        publicKeyParam = null;
                    }
                }
                //如果都解析失败，则返回原串
                if (publicKeyParam == null)
                    return publicKey;
                //输出XML格式密钥
                return string.Format(
                    "<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent></RSAKeyValue>",
                    Convert.ToBase64String(publicKeyParam.Modulus.ToByteArrayUnsigned()),
                    Convert.ToBase64String(publicKeyParam.Exponent.ToByteArrayUnsigned())
                );
            }
            catch (Exception)
            {
                return "error";
            }
        }

//私钥格式转换
public static string RsaPrivateKeyToXml(string privateKey)
        {
            try
            {
                if (string.IsNullOrWhiteSpace(privateKey))
                    return "";
                if (privateKey.Contains("<RSAKeyValue>"))
                    return privateKey;
                RsaPrivateCrtKeyParameters privateKeyParam;
                //尝试进行java格式的密钥读取
                try
                {
                    privateKeyParam = (RsaPrivateCrtKeyParameters)PrivateKeyFactory.CreateKey(Convert.FromBase64String(privateKey));
                }
                catch
                {
                    privateKeyParam = null;
                }
                //非java格式密钥进行pem格式的密钥读取
                if (privateKeyParam == null)
                {
                    try
                    {
                        var pemKey = privateKey;
                        if (!pemKey.Contains("BEGIN RSA PRIVATE KEY"))
                        {
                            pemKey = @"-----BEGIN RSA PRIVATE KEY-----
                           " + privateKey + @"
                           -----END RSA PRIVATE KEY-----";
                        }
                        var array = Encoding.ASCII.GetBytes(pemKey);
                        var stream = new MemoryStream(array);
                        var reader = new StreamReader(stream);
                        var pemReader = new Org.BouncyCastle.OpenSsl.PemReader(reader);
                        var keyPair = (AsymmetricCipherKeyPair)pemReader.ReadObject();
                        privateKeyParam = (RsaPrivateCrtKeyParameters)keyPair.Private;
                    }
                    catch
                    {
                        privateKeyParam = null;
                    }
                }
                //如果都解析失败，则返回原串
                if (privateKeyParam == null)
                    return privateKey;
                //输出XML格式密钥
                return string.Format(
                    "<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent><P>{2}</P><Q>{3}</Q><DP>{4}</DP><DQ>{5}</DQ><InverseQ>{6}</InverseQ><D>{7}</D></RSAKeyValue>",
                    Convert.ToBase64String(privateKeyParam.Modulus.ToByteArrayUnsigned()),
                    Convert.ToBase64String(privateKeyParam.PublicExponent.ToByteArrayUnsigned()),
                    Convert.ToBase64String(privateKeyParam.P.ToByteArrayUnsigned()),
                    Convert.ToBase64String(privateKeyParam.Q.ToByteArrayUnsigned()),
                    Convert.ToBase64String(privateKeyParam.DP.ToByteArrayUnsigned()),
                    Convert.ToBase64String(privateKeyParam.DQ.ToByteArrayUnsigned()),
                    Convert.ToBase64String(privateKeyParam.QInv.ToByteArrayUnsigned()),
                    Convert.ToBase64String(privateKeyParam.Exponent.ToByteArrayUnsigned())
                );
            }
            catch (Exception)
            {
                throw PayException.New("RSA私钥密钥格式转换失败");
            }
        }

2、公钥加密，私钥解密（包括超长字符串的分段加密解密）

public static string RsaEncrypt(string rawInput, string publicKey)
        {
            if (string.IsNullOrEmpty(rawInput))
            {
                return string.Empty;
            }

            if (string.IsNullOrWhiteSpace(publicKey))
            {
                throw new ArgumentException("Invalid Public Key");
            }

            using (var rsaProvider = new RSACryptoServiceProvider())
            {
                var inputBytes = Encoding.UTF8.GetBytes(rawInput);//有含义的字符串转化为字节流
                rsaProvider.FromXmlString(publicKey);//载入公钥
                int bufferSize = (rsaProvider.KeySize / 8) - 11;//单块最大长度
                var buffer = new byte[bufferSize];
                using (MemoryStream inputStream = new MemoryStream(inputBytes),
                     outputStream = new MemoryStream())
                {
                    while (true)
                    { //分段加密
                        int readSize = inputStream.Read(buffer, 0, bufferSize);
                        if (readSize <= 0)
                        {
                            break;
                        }

                        var temp = new byte[readSize];
                        Array.Copy(buffer, 0, temp, 0, readSize);
                        var encryptedBytes = rsaProvider.Encrypt(temp, false);
                        outputStream.Write(encryptedBytes, 0, encryptedBytes.Length);
                    }
                    return Convert.ToBase64String(outputStream.ToArray());//转化为字节流方便传输
                }
            }
        }

        public static string RsaDecrypt(string encryptedInput, string privateKey)
        {
            if (string.IsNullOrEmpty(encryptedInput))
            {
                return string.Empty;
            }

            if (string.IsNullOrWhiteSpace(privateKey))
            {
                throw new ArgumentException("Invalid Private Key");
            }

            using (var rsaProvider = new RSACryptoServiceProvider())
            {
                var inputBytes = Convert.FromBase64String(encryptedInput);
                rsaProvider.FromXmlString(privateKey);
                int bufferSize = rsaProvider.KeySize / 8;
                var buffer = new byte[bufferSize];
                using (MemoryStream inputStream = new MemoryStream(inputBytes),
                     outputStream = new MemoryStream())
                {
                    while (true)
                    {
                        int readSize = inputStream.Read(buffer, 0, bufferSize);
                        if (readSize <= 0)
                        {
                            break;
                        }

                        var temp = new byte[readSize];
                        Array.Copy(buffer, 0, temp, 0, readSize);
                        var rawBytes = rsaProvider.Decrypt(temp, false);
                        outputStream.Write(rawBytes, 0, rawBytes.Length);
                    }
                    return Encoding.UTF8.GetString(outputStream.ToArray());
                }
            }
        }

3、私钥加密，公钥解密（包括超长字符串的分段加密解密）

/// <summary>
        /// RSA加密 使用私钥加密
        /// </summary>
        /// <param name="byteData"></param>
        /// <param name="key"></param>
        /// <returns></returns>
        private static string RSAEncrypt(string data, string key)
        {
            byte[] byteData = Encoding.UTF8.GetBytes(data);
            var privateRsa = GetRsaCryptoFromXml(key);
            //转换密钥  下面的DotNetUtilities来自Org.BouncyCastle.Security
            var keyPair = DotNetUtilities.GetKeyPair(privateRsa);

            var c = CipherUtilities.GetCipher("RSA/ECB/PKCS1Padding");

            c.Init(true, keyPair.Private);//取私钥（true为加密）

           
            int bufferSize = (privateRsa.KeySize / 8) - 11;//单块最大长度
            var buffer = new byte[bufferSize];
            using (MemoryStream inputStream = new MemoryStream(byteData), outputStream = new MemoryStream())
            {
                while (true)
                { //分段加密
                    int readSize = inputStream.Read(buffer, 0, bufferSize);
                    if (readSize <= 0)
                    {
                        break;
                    }

                    var temp = new byte[readSize];
                    Array.Copy(buffer, 0, temp, 0, readSize);
                    //var encryptedBytes = rsaProvider.Encrypt(temp, false);
                    var encryptedBytes = c.DoFinal(temp);
                    outputStream.Write(encryptedBytes, 0, encryptedBytes.Length);
                }
                return Convert.ToBase64String( outputStream.ToArray());//转化为字节流方便传输
            }
            
        }

        /// <summary>
        /// RSA解密 使用公钥解密
        /// </summary>
        /// <param name="byteData"></param>
        /// <param name="key"></param>
        /// <returns></returns>
        private static string RSADecrypt(string data, string key)
        {
            byte[] byteData= Convert.FromBase64String(data);
            var privateRsa = GetRsaCryptoFromXml(key);
            //转换密钥  
            var keyPair = DotNetUtilities.GetRsaPublicKey(privateRsa);

            var c = CipherUtilities.GetCipher("RSA/ECB/PKCS1Padding");

            c.Init(false, keyPair);//取公钥（false为解密）

            using (MemoryStream inputStream = new MemoryStream(byteData), outputStream = new MemoryStream())
            {
                int restLength = byteData.Length;
                while (restLength > 0)
                {
                    int readLength = restLength < 128 ? restLength : 128;
                    restLength = restLength - readLength;
                    byte[] readBytes = new byte[readLength];
                    inputStream.Read(readBytes, 0, readLength);
                    byte[] append = c.DoFinal(readBytes);
                    outputStream.Write(append, 0, append.Length);
                }
                //注意，这里不一定就是用utf8的编码方式,这个主要看加密的时候用的什么编码方式
                return Encoding.UTF8.GetString(outputStream.ToArray());
            }
            
        }