C# -RSA加密解密帮助类（非对称加密）

/************************************************************
* Description: RSA 非对称 加密、解密
* Create Time: 2021-05-18
* Author：huioo
* Version: v1.0.1
************************************************************/

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Xml;

namespace COMMON.CODES_AND_CIPHERS
{
    /// 
    /// RSa 加密、解密
    /// 主要方法如下：
    /// 01. Encrypt(string text, string public_key)  //RSA 加密字符串
    /// 02. Decrypt(string text, string public_key)  //RSA 解密字符串
    /// 
    public class RSACryption
    {


        #region 加密字符串

        private static bool CompareBytearrays(byte[] a, byte[] b)
        {
            if (a.Length != b.Length)
                return false;
            int i = 0;
            foreach (byte c in a)
            {
                if (c != b[i])
                    return false;
                i++;
            }
            return true;
        }


        public static RSA CreateRsaProviderFromPublicKey(string publicKeyString)
        {
            // encoded OID sequence for  PKCS #1 rsaEncryption szOID_RSA_RSA = "1.2.840.113549.1.1.1"
            byte[] seqOid = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
            byte[] seq = new byte[15];

            var x509Key = Convert.FromBase64String(publicKeyString);

            // ---------  Set up stream to read the asn.1 encoded SubjectPublicKeyInfo blob  ------
            using (MemoryStream mem = new MemoryStream(x509Key))
            {
                using (BinaryReader binr = new BinaryReader(mem))  //wrap Memory Stream with BinaryReader for easy reading
                {
                    byte bt = 0;
                    ushort twobytes = 0;

                    twobytes = binr.ReadUInt16();
                    if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
                        binr.ReadByte();    //advance 1 byte
                    else if (twobytes == 0x8230)
                        binr.ReadInt16();   //advance 2 bytes
                    else
                        return null;

                    seq = binr.ReadBytes(15);       //read the Sequence OID
                    if (!CompareBytearrays(seq, seqOid))    //make sure Sequence for OID is correct
                        return null;

                    twobytes = binr.ReadUInt16();
                    if (twobytes == 0x8103) //data read as little endian order (actual data order for Bit String is 03 81)
                        binr.ReadByte();    //advance 1 byte
                    else if (twobytes == 0x8203)
                        binr.ReadInt16();   //advance 2 bytes
                    else
                        return null;

                    bt = binr.ReadByte();
                    if (bt != 0x00)     //expect null byte next
                        return null;

                    twobytes = binr.ReadUInt16();
                    if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
                        binr.ReadByte();    //advance 1 byte
                    else if (twobytes == 0x8230)
                        binr.ReadInt16();   //advance 2 bytes
                    else
                        return null;

                    twobytes = binr.ReadUInt16();
                    byte lowbyte = 0x00;
                    byte highbyte = 0x00;

                    if (twobytes == 0x8102) //data read as little endian order (actual data order for Integer is 02 81)
                        lowbyte = binr.ReadByte();  // read next bytes which is bytes in modulus
                    else if (twobytes == 0x8202)
                    {
                        highbyte = binr.ReadByte(); //advance 2 bytes
                        lowbyte = binr.ReadByte();
                    }
                    else
                        return null;
                    byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };   //reverse byte order since asn.1 key uses big endian order
                    int modsize = BitConverter.ToInt32(modint, 0);

                    int firstbyte = binr.PeekChar();
                    if (firstbyte == 0x00)
                    {   //if first byte (highest order) of modulus is zero, don't include it
                        binr.ReadByte();    //skip this null byte
                        modsize -= 1;   //reduce modulus buffer size by 1
                    }

                    byte[] modulus = binr.ReadBytes(modsize);   //read the modulus bytes

                    if (binr.ReadByte() != 0x02)            //expect an Integer for the exponent data
                        return null;
                    int expbytes = (int)binr.ReadByte();        // should only need one byte for actual exponent data (for all useful values)
                    byte[] exponent = binr.ReadBytes(expbytes);

                    // ------- create RSACryptoServiceProvider instance and initialize with public key -----
                    var rsa = RSA.Create();
                    RSAParameters rsaKeyInfo = new RSAParameters
                    {
                        Modulus = modulus,
                        Exponent = exponent
                    };
                    rsa.ImportParameters(rsaKeyInfo);

                    return rsa;
                }

            }
        }

        /// 
        /// RSA 加密字符串
        /// 
        /// 明文
        /// 公钥
        /// 密文
        public static byte[] Encrypt(string text, string public_key)
        {
            RSA _publicKeyRsaProvider = CreateRsaProviderFromPublicKey(public_key);

            byte[] bytes = Encoding.UTF8.GetBytes(text);
            return _publicKeyRsaProvider.Encrypt(bytes, RSAEncryptionPadding.Pkcs1);
        }

        /// 
        /// RSA 加密字符串
        /// 
        /// 明文
        /// 公钥
        /// 填充模式（默认：RSAEncryptionPadding.Pkcs1）
        /// 密文
        public static byte[] Encrypt(string text, string public_key, RSAEncryptionPadding padding)
        {
            RSA _publicKeyRsaProvider = CreateRsaProviderFromPublicKey(public_key);

            byte[] bytes = Encoding.UTF8.GetBytes(text);
            return _publicKeyRsaProvider.Encrypt(bytes, padding);
        }

        #endregion

        #region 解密字符串

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

            if (bt == 0x81)
                count = binr.ReadByte();
            else
            if (bt == 0x82)
            {
                var highbyte = binr.ReadByte();
                var 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;
        }

        public static RSA CreateRsaProviderFromPrivateKey(string privateKey)
        {
            var privateKeyBits = Convert.FromBase64String(privateKey);

            var rsa = RSA.Create();
            var rsaParameters = new RSAParameters();

            using (BinaryReader binr = new BinaryReader(new MemoryStream(privateKeyBits)))
            {
                byte bt = 0;
                ushort twobytes = 0;
                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8130)
                    binr.ReadByte();
                else if (twobytes == 0x8230)
                    binr.ReadInt16();
                else
                    throw new Exception("Unexpected value read binr.ReadUInt16()");

                twobytes = binr.ReadUInt16();
                if (twobytes != 0x0102)
                    throw new Exception("Unexpected version");

                bt = binr.ReadByte();
                if (bt != 0x00)
                    throw new Exception("Unexpected value read binr.ReadByte()");

                rsaParameters.Modulus = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.Exponent = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.D = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.P = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.Q = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.DP = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.DQ = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.InverseQ = binr.ReadBytes(GetIntegerSize(binr));
            }

            rsa.ImportParameters(rsaParameters);
            return rsa;
        }

        /// 
        /// RSA 解密字符串
        /// 
        /// 明文
        /// 私钥
        /// 填充模式（默认：RSAEncryptionPadding.Pkcs1）
        /// 密文
        public static byte[] Decrypt(string text, string private_key)
        {
            RSA _privateKeyRsaProvider = CreateRsaProviderFromPrivateKey(private_key);

            byte[] bytes = Encoding.UTF8.GetBytes(text);
            return _privateKeyRsaProvider.Decrypt(bytes, RSAEncryptionPadding.Pkcs1);
        }

        /// 
        /// RSA 解密字符串
        /// 
        /// 明文
        /// 私钥
        /// 填充模式（默认：RSAEncryptionPadding.Pkcs1）
        /// 密文
        public static byte[] Decrypt(string text, string private_key, RSAEncryptionPadding padding)
        {
            RSA _privateKeyRsaProvider = CreateRsaProviderFromPrivateKey(private_key);
            byte[] bytes = Encoding.UTF8.GetBytes(text);
            return _privateKeyRsaProvider.Decrypt(bytes, padding);
        }
        #endregion

    }


    /// 
    /// RSA算法类型
    /// 
    public enum RSAType
    {
        /// 
        /// SHA1
        /// 
        RSA = 0,
        /// 
        /// RSA2 密钥长度至少为2048
        /// SHA256
        /// 
        RSA2
    }

    /// 
    /// https://www.cnblogs.com/stulzq/p/7757915.html
    /// 
    /// RSA加解密 使用OpenSSL的公钥加密/私钥解密
    /// 作者：李志强
    /// 创建时间：2017年10月30日15:50:14
    /// QQ:501232752
    /// 
    public class RSAHelper
    {
        private readonly RSA _privateKeyRsaProvider;
        private readonly RSA _publicKeyRsaProvider;
        private readonly HashAlgorithmName _hashAlgorithmName;
        private readonly Encoding _encoding;

        /// 
        /// 实例化RSAHelper
        /// 
        /// 加密算法类型 RSA SHA1;RSA2 SHA256 密钥长度至少为2048
        /// 编码类型
        /// 私钥
        /// 公钥
        public RSAHelper(RSAType rsaType, Encoding encoding, string privateKey, string publicKey = null)
        {
            _encoding = encoding;
            if (!string.IsNullOrEmpty(privateKey))
            {
                _privateKeyRsaProvider = CreateRsaProviderFromPrivateKey(privateKey);
            }

            if (!string.IsNullOrEmpty(publicKey))
            {
                _publicKeyRsaProvider = CreateRsaProviderFromPublicKey(publicKey);
            }

            _hashAlgorithmName = rsaType == RSAType.RSA ? HashAlgorithmName.SHA1 : HashAlgorithmName.SHA256;
        }

        #region 使用私钥签名

        /// 
        /// 使用私钥签名
        /// 
        /// 原始数据
        /// 
        public string Sign(string data)
        {
            byte[] dataBytes = _encoding.GetBytes(data);

            var signatureBytes = _privateKeyRsaProvider.SignData(dataBytes, _hashAlgorithmName, RSASignaturePadding.Pkcs1);

            return Convert.ToBase64String(signatureBytes);
        }

        #endregion

        #region 使用公钥验证签名

        /// 
        /// 使用公钥验证签名
        /// 
        /// 原始数据
        /// 签名
        /// 
        public bool Verify(string data, string sign)
        {
            byte[] dataBytes = _encoding.GetBytes(data);
            byte[] signBytes = Convert.FromBase64String(sign);

            var verify = _publicKeyRsaProvider.VerifyData(dataBytes, signBytes, _hashAlgorithmName, RSASignaturePadding.Pkcs1);

            return verify;
        }

        #endregion

        #region 解密

        public string Decrypt(string cipherText)
        {
            if (_privateKeyRsaProvider == null)
            {
                throw new Exception("_privateKeyRsaProvider is null");
            }
            return Encoding.UTF8.GetString(_privateKeyRsaProvider.Decrypt(Convert.FromBase64String(cipherText), RSAEncryptionPadding.Pkcs1));
        }

        #endregion

        #region 加密

        public string Encrypt(string text)
        {
            if (_publicKeyRsaProvider == null)
            {
                throw new Exception("_publicKeyRsaProvider is null");
            }
            return Convert.ToBase64String(_publicKeyRsaProvider.Encrypt(Encoding.UTF8.GetBytes(text), RSAEncryptionPadding.Pkcs1));
        }

        #endregion

        #region 使用私钥创建RSA实例

        public RSA CreateRsaProviderFromPrivateKey(string privateKey)
        {
            var privateKeyBits = Convert.FromBase64String(privateKey);

            var rsa = RSA.Create();
            var rsaParameters = new RSAParameters();

            using (BinaryReader binr = new BinaryReader(new MemoryStream(privateKeyBits)))
            {
                byte bt = 0;
                ushort twobytes = 0;
                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8130)
                    binr.ReadByte();
                else if (twobytes == 0x8230)
                    binr.ReadInt16();
                else
                    throw new Exception("Unexpected value read binr.ReadUInt16()");

                twobytes = binr.ReadUInt16();
                if (twobytes != 0x0102)
                    throw new Exception("Unexpected version");

                bt = binr.ReadByte();
                if (bt != 0x00)
                    throw new Exception("Unexpected value read binr.ReadByte()");

                rsaParameters.Modulus = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.Exponent = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.D = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.P = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.Q = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.DP = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.DQ = binr.ReadBytes(GetIntegerSize(binr));
                rsaParameters.InverseQ = binr.ReadBytes(GetIntegerSize(binr));
            }

            rsa.ImportParameters(rsaParameters);
            return rsa;
        }

        #endregion

        #region 使用公钥创建RSA实例

        public RSA CreateRsaProviderFromPublicKey(string publicKeyString)
        {
            // encoded OID sequence for  PKCS #1 rsaEncryption szOID_RSA_RSA = "1.2.840.113549.1.1.1"
            byte[] seqOid = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
            byte[] seq = new byte[15];

            var x509Key = Convert.FromBase64String(publicKeyString);

            // ---------  Set up stream to read the asn.1 encoded SubjectPublicKeyInfo blob  ------
            using (MemoryStream mem = new MemoryStream(x509Key))
            {
                using (BinaryReader binr = new BinaryReader(mem))  //wrap Memory Stream with BinaryReader for easy reading
                {
                    byte bt = 0;
                    ushort twobytes = 0;

                    twobytes = binr.ReadUInt16();
                    if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
                        binr.ReadByte();    //advance 1 byte
                    else if (twobytes == 0x8230)
                        binr.ReadInt16();   //advance 2 bytes
                    else
                        return null;

                    seq = binr.ReadBytes(15);       //read the Sequence OID
                    if (!CompareBytearrays(seq, seqOid))    //make sure Sequence for OID is correct
                        return null;

                    twobytes = binr.ReadUInt16();
                    if (twobytes == 0x8103) //data read as little endian order (actual data order for Bit String is 03 81)
                        binr.ReadByte();    //advance 1 byte
                    else if (twobytes == 0x8203)
                        binr.ReadInt16();   //advance 2 bytes
                    else
                        return null;

                    bt = binr.ReadByte();
                    if (bt != 0x00)     //expect null byte next
                        return null;

                    twobytes = binr.ReadUInt16();
                    if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
                        binr.ReadByte();    //advance 1 byte
                    else if (twobytes == 0x8230)
                        binr.ReadInt16();   //advance 2 bytes
                    else
                        return null;

                    twobytes = binr.ReadUInt16();
                    byte lowbyte = 0x00;
                    byte highbyte = 0x00;

                    if (twobytes == 0x8102) //data read as little endian order (actual data order for Integer is 02 81)
                        lowbyte = binr.ReadByte();  // read next bytes which is bytes in modulus
                    else if (twobytes == 0x8202)
                    {
                        highbyte = binr.ReadByte(); //advance 2 bytes
                        lowbyte = binr.ReadByte();
                    }
                    else
                        return null;
                    byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };   //reverse byte order since asn.1 key uses big endian order
                    int modsize = BitConverter.ToInt32(modint, 0);

                    int firstbyte = binr.PeekChar();
                    if (firstbyte == 0x00)
                    {   //if first byte (highest order) of modulus is zero, don't include it
                        binr.ReadByte();    //skip this null byte
                        modsize -= 1;   //reduce modulus buffer size by 1
                    }

                    byte[] modulus = binr.ReadBytes(modsize);   //read the modulus bytes

                    if (binr.ReadByte() != 0x02)            //expect an Integer for the exponent data
                        return null;
                    int expbytes = (int)binr.ReadByte();        // should only need one byte for actual exponent data (for all useful values)
                    byte[] exponent = binr.ReadBytes(expbytes);

                    // ------- create RSACryptoServiceProvider instance and initialize with public key -----
                    var rsa = RSA.Create();
                    RSAParameters rsaKeyInfo = new RSAParameters
                    {
                        Modulus = modulus,
                        Exponent = exponent
                    };
                    rsa.ImportParameters(rsaKeyInfo);

                    return rsa;
                }

            }
        }

        #endregion

        #region 导入密钥算法

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

            if (bt == 0x81)
                count = binr.ReadByte();
            else
            if (bt == 0x82)
            {
                var highbyte = binr.ReadByte();
                var 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;
        }

        private bool CompareBytearrays(byte[] a, byte[] b)
        {
            if (a.Length != b.Length)
                return false;
            int i = 0;
            foreach (byte c in a)
            {
                if (c != b[i])
                    return false;
                i++;
            }
            return true;
        }

        #endregion

    }

    /// 
    /// https://www.cnblogs.com/CreateMyself/p/9853736.html
    /// 
    public static class RSAHelper1
    {
        private const string privateKey = "0wE26IHp4U9OLtPhJ+fT8ej6aWORFP8pd++MjUuhkQQm/zhcImbxQbjxtSAftz+kkDwGDFJpSldQPyigOGcUx7PofTc6VhiFik9E9SsxV9n0iEEtqUndDfmBJfPAWt+4UDMwKakgZqFoapDuwjKlTErFvKCyKCs+qN9OZvZwKWk=AQAB
8Ei6NIsZtgV3DQjuGHfGLS6o1O+IUXxzjqLxdMm77yhEPUxR9YPIxODJ2VVTddXSAHxViJJt30yJ7JhVz6cpQw==
4M49NrmalgVQFMsea2RMB1qN8fAPfIw5G9q9hzsLcWSCmkeRRIQlvPYflVEKAYKiDVVzENETbnnduFXWBABx4w==t+JQbemN0Zi5FQaif6MZzHYKynpNTl75aE0Wj5Pa+RlNr8N6bXNe8Bw/HM2Jw4HQ5oJASvYUk3DVlHS4JuP8VQ==lT62iv9brp9mU/epgVh71SH8PJPIZEJfo6tryjyb0zMMNcqvmZI1z6aCv0mm3+vPFBUXqCF1yhFj7n4l8FAvSw==flrvgxHvf4l+fdymEVDgKjsfGqshOpppoNgZj9kpeWBto3o8z++Ki6eSLQT3nVnpx2QCZeTWkxTED4nhSLKscw==cQTCg1Eqk7sltmFYxUYgOP/AOPjSufteG9acYwYymPkvZh6rAuY+rSRBmvGE62NUYskzuB/gM6iG2/2HrA5SixfNgCvZ+nsK+kX5pzQRsYdD71ViQW0hOanXwj45I2zHRgBiuTtCUP0fs5pISmQkaeJkDL5pO2l+wvlgl+wunj0=";
        private const string publicKey = "0wE26IHp4U9OLtPhJ+fT8ej6aWORFP8pd++MjUuhkQQm/zhcImbxQbjxtSAftz+kkDwGDFJpSldQPyigOGcUx7PofTc6VhiFik9E9SsxV9n0iEEtqUndDfmBJfPAWt+4UDMwKakgZqFoapDuwjKlTErFvKCyKCs+qN9OZvZwKWk=AQAB";

        public static byte[] Encrypt(byte[] encryptBytes, RSAEncryptionPadding padding)
        {
            using (var rsa = RSA.Create())
            {

                FromXmlString(rsa, publicKey);

                var maxBlockSize = GetMaxBlockSize(rsa, padding);

                if (encryptBytes.Length <= maxBlockSize)
                {
                    var @bytes = rsa.Encrypt(encryptBytes, padding);
                    return @bytes;
                }

                using (var memoryStream = new MemoryStream(encryptBytes))
                {
                    using (var readStream = new MemoryStream())
                    {
                        byte[] buffer = new byte[maxBlockSize];

                        int blockSize = memoryStream.Read(buffer, 0, maxBlockSize);

                        while (blockSize > 0)
                        {
                            var blockByte = new byte[blockSize];

                            Array.Copy(buffer, 0, blockByte, 0, blockSize);

                            var encrypts = rsa.Encrypt(blockByte, padding);

                            readStream.Write(encrypts, 0, encrypts.Length);

                            blockSize = memoryStream.Read(buffer, 0, maxBlockSize);
                        }

                        return readStream.ToArray();
                    }
                }
            }
        }

        public static byte[] Decrypt(byte[] decryptBytes, RSAEncryptionPadding padding)
        {
            using (var rsa = RSA.Create())
            {
                FromXmlString(rsa, privateKey);

                var maxBlockSize = rsa.KeySize / 8;

                if (decryptBytes.Length <= maxBlockSize)
                {
                    var @bytes = rsa.Decrypt(decryptBytes, padding);
                    return @bytes;
                }

                using (var memoryStream = new MemoryStream(decryptBytes))
                {
                    using (var readStream = new MemoryStream())
                    {
                        var buffer = new byte[maxBlockSize];

                        var blockSize = memoryStream.Read(buffer, 0, maxBlockSize);

                        while (blockSize > 0)
                        {
                            var blockByte = new byte[blockSize];

                            Array.Copy(buffer, 0, blockByte, 0, blockSize);

                            var decrypts = rsa.Decrypt(blockByte, padding);

                            readStream.Write(decrypts, 0, decrypts.Length);

                            blockSize = memoryStream.Read(buffer, 0, maxBlockSize);
                        }

                        return readStream.ToArray();
                    }
                }
            }
        }

        public static void FromXmlString(RSA rsa, string xmlString)
        {
            RSAParameters parameters = new RSAParameters();

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.LoadXml(xmlString);

            if (xmlDoc.DocumentElement.Name.Equals("RSAKeyValue"))
            {
                foreach (XmlNode node in xmlDoc.DocumentElement.ChildNodes)
                {
                    switch (node.Name)
                    {
                        case "Modulus": parameters.Modulus = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
                        case "Exponent": parameters.Exponent = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
                        case "P": parameters.P = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
                        case "Q": parameters.Q = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
                        case "DP": parameters.DP = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
                        case "DQ": parameters.DQ = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
                        case "InverseQ": parameters.InverseQ = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
                        case "D": parameters.D = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
                    }
                }
            }
            else
            {
                throw new Exception("Invalid XML RSA key.");
            }

            rsa.ImportParameters(parameters);
        }

        static int GetMaxBlockSize(RSA rsa, RSAEncryptionPadding padding)
        {
            var offset = 0;
            if (padding.Mode == RSAEncryptionPaddingMode.Pkcs1)
            {
                offset = 11;
            }
            else
            {
                if (padding.Equals(RSAEncryptionPadding.OaepSHA1))
                {
                    offset = 42;
                }

                if (padding.Equals(RSAEncryptionPadding.OaepSHA256))
                {
                    offset = 66;
                }

                if (padding.Equals(RSAEncryptionPadding.OaepSHA384))
                {
                    offset = 98;
                }

                if (padding.Equals(RSAEncryptionPadding.OaepSHA512))
                {
                    offset = 130;
                }
            }
            return rsa.KeySize / 8 - offset;
        }

        public static void Main(string[] args)
        {
            var encryptString = "0";
            for (int i = 1; i < 2000; i++)
            {
                encryptString += i;
            }

            Console.WriteLine(encryptString.Length);

            var encryptBytes = Encoding.UTF8.GetBytes(encryptString);

            //加密后字节数组
            var resultBytes = RSAHelper1.Encrypt(encryptBytes, RSAEncryptionPadding.Pkcs1);

            //解密后字节数组
            var decryptBytes = RSAHelper1.Decrypt(resultBytes, RSAEncryptionPadding.Pkcs1);

            //解密结果
            var result = Encoding.UTF8.GetString(decryptBytes);

            //比较加密字符串和解密结果是否相等
            Console.WriteLine(encryptString == result);
            Console.ReadKey();
        }
    }
}
算法加密解密RSA非对称

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