C# 无法强制转换类型为'；RSACng&x27；输入'；System.Security.Cryptography.rsacyptoserviceprovider'；

我得到了一个例外：

无法将“RSACng”类型的对象强制转换为“System.Security.Cryptography.rsacCryptoServiceProvider”类型

调用此方法：

GoogleCredential cred = GoogleCredential.FromFile(path);

完全例外：

Unable to cast object of type 'RSACng' to type 'System.Security.Cryptography.RSACryptoServiceProvider'
   at Google.Apis.Auth.OAuth2.ServiceAccountCredential.Initializer.FromPrivateKey(String privateKey) in C:\Apiary\2019-09-11.10-11-15\Src\Support\Google.Apis.Auth\OAuth2\ServiceAccountCredential.cs:line 110
   at Google.Apis.Auth.OAuth2.DefaultCredentialProvider.CreateServiceAccountCredentialFromParameters(JsonCredentialParameters credentialParameters) in C:\Apiary\2019-09-11.10-11-15\Src\Support\Google.Apis.Auth\OAuth2\DefaultCredentialProvider.cs:line 243
   at Google.Apis.Auth.OAuth2.DefaultCredentialProvider.CreateDefaultCredentialFromParameters(JsonCredentialParameters credentialParameters) in C:\Apiary\2019-09-11.10-11-15\Src\Support\Google.Apis.Auth\OAuth2\DefaultCredentialProvider.cs:line 197
   at Google.Apis.Auth.OAuth2.GoogleCredential.FromFile(String path) in C:\Apiary\2019-09-11.10-11-15\Src\Support\Google.Apis.Auth\OAuth2\GoogleCredential.cs:line 114
   at ServerUtil.GCloudReporter..ctor(String version, String deployEnv)  

使用.NET Framework 4.5.1

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Google API libs版本1.41.1

问题在于应用程序在.NET核心环境中运行，但此特定代码在.NET Framework的项目设置中。将代码移动到带有.NET Core安装程序的项目修复了此问题

.NET核心 步骤1:nuget pkg的insall System.Security.Cryptography.Cng 步骤2：创建类“X509Certificate2Signature”

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步骤3：在此行中，IExternalSignature externalSignature=new X509Certificate2Signature（证书，“SHA1”）；指向最近创建的类“X509Certificate2Signature”。

查看此代码会尝试将RSA.Create（）方法的结果强制转换为rsacryptServiceProvider。类RSA的工厂方法可以被machine.config覆盖，并且对于不同的.NET运行时，默认方法也可以不同，有关详细信息，请参见此处。可能没有人对此进行过深入测试：-）@Yuri你说问题在于应用程序运行在.NET core中，然后你将代码移动到了.NET core项目中。困惑，它已经在那里了。你明白了，所以请与社区分享。

    using iTextSharp.text.pdf.security;
using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Text;

namespace DigiSignNETCORE
{
    public class X509Certificate2Signature : IExternalSignature
    {
        private String hashAlgorithm;
        private String encryptionAlgorithm;
        private X509Certificate2 certificate;

        public X509Certificate2Signature(X509Certificate2 certificate, String hashAlgorithm)
        {
            if (!certificate.HasPrivateKey)
                throw new ArgumentException("No private key.");
            this.certificate = certificate;
            this.hashAlgorithm = DigestAlgorithms.GetDigest(DigestAlgorithms.GetAllowedDigests(hashAlgorithm));
            if (certificate.PrivateKey is RSACryptoServiceProvider)
                encryptionAlgorithm = "RSA";
            else if (certificate.PrivateKey is DSACryptoServiceProvider)
                encryptionAlgorithm = "DSA";
            
            else if (certificate.PrivateKey is System.Security.Cryptography.RSACng)
                encryptionAlgorithm = "RSA";
        }

        public virtual byte[] Sign(byte[] message)
        {
            if (certificate.PrivateKey is RSACryptoServiceProvider)
            {
                RSACryptoServiceProvider rsa = (RSACryptoServiceProvider)certificate.PrivateKey;
                return rsa.SignData(message, hashAlgorithm);
            }
           else if (certificate.PrivateKey is System.Security.Cryptography.RSACng)
            {
                System.Security.Cryptography.RSACng rSACng = (System.Security.Cryptography.RSACng)certificate.PrivateKey;
                return rSACng.SignData(message,HashAlgorithmName.SHA1,RSASignaturePadding.Pkcs1);
            }

            else
            {
                DSACryptoServiceProvider dsa = (DSACryptoServiceProvider)certificate.PrivateKey;
                return dsa.SignData(message);
            }
        }

        public virtual String GetHashAlgorithm()
        {
            return hashAlgorithm;
        }

        public virtual String GetEncryptionAlgorithm()
        {
            return encryptionAlgorithm;
        }
    }
}