.net通用RSA加密工具类

目前最流行的加密算法莫过于RSA了，以下是我们.net/.net core C#生成环境用的RSA加密工具类，在此分享给大家。

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

namespace Common
{
    /// <summary>
    /// RSA加密工具类
    /// </summary>
    public class RSACryptoUtil
    {
        /// <summary>
        /// rsa私钥
        /// </summary>
        private static readonly RSACryptoServiceProvider _privateKeyRsaProvider;
        /// <summary>
        /// rsa公钥
        /// </summary>
        private static readonly RSACryptoServiceProvider _publicKeyRsaProvider;

        static RSACryptoUtil()
        {
            //string root = AppDomain.CurrentDomain.RelativeSearchPath;

            string publicKey = @"MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqc7Mgsct5yaU+Ihxwz28luI/0xJe/uZQPwkMyOJpz+tDi5p9V0JYaYg3SrhIqkNQFluBBSRCnp1NNzfT3qUn93eJ1g9/8wwBloiK+W0s6DuSQj93+T8ZM1+qnnBOUiNrHBmynjR1frN4CJVmdXP1+w3CqLoMaHkw46Vy5UvEf9yedetjcCwIbmjRJzE2Mv3qQz67HbgQIDAQAB";//File.ReadAllText($"公钥位置", Encoding.ASCII);
            string privateKey = @"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";//File.ReadAllText($"私钥位置", Encoding.ASCII);

            if (!string.IsNullOrWhiteSpace(publicKey))
            {
                _publicKeyRsaProvider = CreateRsaProviderFromPublicKey(publicKey);
            }
            if (!string.IsNullOrWhiteSpace(privateKey))
            {
                _privateKeyRsaProvider = CreateRsaProviderFromPrivateKey(privateKey);
            }
        }

        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="cipherText"></param>
        /// <returns></returns>
        public static string Decrypt(string cipherText)
        {
            if (_privateKeyRsaProvider == null)
            {
                LogUtil.Logger.Error("_privateKeyRsaProvider is null");
                return string.Empty;
            }

            try
            {
                return Encoding.UTF8.GetString(_privateKeyRsaProvider.Decrypt(Convert.FromBase64String(cipherText), false));
            }
            catch (Exception ex)
            {
                LogUtil.Logger.Error(ex, $"RSA解密失败：{cipherText}");
                return string.Empty;
            }
        }

        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="text"></param>
        /// <returns></returns>
        public static string Encrypt(string text)
        {
            if (_publicKeyRsaProvider == null)
            {
                LogUtil.Logger.Error("_publicKeyRsaProvider is null");
                return string.Empty;
            }

            return Convert.ToBase64String(_publicKeyRsaProvider.Encrypt(Encoding.UTF8.GetBytes(text), false));
        }

        /// <summary>
        /// 创建rsa公钥对象
        /// </summary>
        /// <param name="publicKeyString"></param>
        /// <returns></returns>
        private static RSACryptoServiceProvider 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[] 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
                {
                    ushort 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;

                    byte[] 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;

                    byte 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 = 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 -----
                    RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
                    RSAParameters RSAKeyInfo = new RSAParameters();
                    RSAKeyInfo.Modulus = modulus;
                    RSAKeyInfo.Exponent = exponent;
                    RSA.ImportParameters(RSAKeyInfo);

                    return RSA;
                }
            }
        }

        /// <summary>
        /// 创建rsa私钥对象
        /// </summary>
        /// <param name="privateKey"></param>
        /// <returns></returns>
        private static RSACryptoServiceProvider CreateRsaProviderFromPrivateKey(string privateKey)
        {
            var privateKeyBits = Convert.FromBase64String(privateKey);

            var RSA = new RSACryptoServiceProvider();
            var RSAparams = new RSAParameters();

            using (BinaryReader binr = new BinaryReader(new MemoryStream(privateKeyBits)))
            {
                ushort 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");

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

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

            RSA.ImportParameters(RSAparams);
            return RSA;
        }

        private static int GetIntegerSize(BinaryReader binr)
        {
            int count;

            byte bt = binr.ReadByte();

            if (bt != 0x02) return 0;
            bt = binr.ReadByte();

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

以上公钥私钥不可用，如需生成请使用“支付宝开放平台密钥工具”，官方下载链接：密钥工具下载 - 支付宝文档中心 (alipay.com)

以下是工具使用步骤：

第一步：选择RSA2算法，生成密钥

第二步：复制公钥，直接赋值给工具类变量“publicKey”，复制私钥，进行下一步使用

第三步：到“格式转换”栏，把私钥粘贴到“应用私钥”，点击“转换”，我们可以看到下边有“PKCS1”字样，这就是.net环境中RSA算法支持的私钥格式，复制“输出”，赋值给“privateKey”即可。

以上就是工具使用步骤，快来用最安全的对称加密算法加密你的内容吧！