在我的情况下，尝试将 本地商店证书 转换为 RSACryptoServiceProvider 时发生了同样的问题，如下所示：
RSACryptoServiceProvider encryptProvider =
certificate.PrivateKey as RSACryptoServiceProvider;
使用RSA 而不是RSACryptoServiceProvider 解决了这个问题。
在此处提供说明，以防有人好奇如何执行此操作））。
要将一些证书存储到您的机器中，请打开 Visual Studio 开发人员命令并输入以下内容：
makecert -n "CN=JohnDoe" -sr currentuser -ss someCertStore
...您可以在其中指定和值，而不是“JohnDoe”和“demoCertStore”。
现在您可以使用以下代码从本地证书存储区访问证书：
public class Program
{
static void DumpBytes(string title, byte[] bytes)
{
Console.Write(title);
foreach (byte b in bytes)
{
Console.Write("{0:X} ", b);
}
Console.WriteLine();
}
static void Main(string[] args)
{
// This will convert our input string into bytes and back
var converter = new ASCIIEncoding();
// Get a crypto provider out of the certificate store
// should be wrapped in using for production code
var store = new X509Store("someCertStore", StoreLocation.CurrentUser);
store.Open(OpenFlags.ReadOnly);
// should be wrapped in using for production code
X509Certificate2 certificate = store.Certificates[0];
RSA rsa = (RSA)certificate.PrivateKey;
(certificate.PrivateKey as RSACng)?.Key.SetProperty(
new CngProperty(
"Export Policy",
BitConverter.GetBytes((int)CngExportPolicies.AllowPlaintextExport),
CngPropertyOptions.Persist));
string messageToSign = "This is the message I want to sign";
Console.WriteLine("Message: {0}", messageToSign);
byte[] messageToSignBytes = converter.GetBytes(messageToSign);
// need to calculate a hash for this message - this will go into the
// signature and be used to verify the message
// Create an implementation of the hashing algorithm we are going to us
// should be wrapped in using for production code
DumpBytes("Message to sign in bytes: ", messageToSignBytes);
HashAlgorithm hasher = new SHA1Managed();
// Use the hasher to hash the message
byte[] hash = hasher.ComputeHash(messageToSignBytes);
DumpBytes("Hash for message: ", hash);
// Now sign the hash to create a signature
byte[] signature = rsa.SignHash(hash, HashAlgorithmName.SHA1, RSASignaturePadding.Pss);
DumpBytes("Signature: ", messageToSignBytes);
// Now use the signature to perform a successful validation of the mess
bool validSignature = rsa.VerifyHash(hash: hash,
signature: signature,
hashAlgorithm: HashAlgorithmName.SHA1,
padding: RSASignaturePadding.Pss);
Console.WriteLine("Correct signature validated OK: {0}", validSignature);
// Change one byte of the signature
signature[0] = 99;
// Now try the using the incorrect signature to validate the message
bool invalidSignature = rsa.VerifyHash(hash: hash,
signature: signature,
hashAlgorithm: HashAlgorithmName.SHA1,
padding: RSASignaturePadding.Pss);
Console.WriteLine("Incorrect signature validated OK: {0}", invalidSignature);
Console.ReadKey();
}