public static string SignData(byte[] data, X509Certificate2 certificate)
        {
            ContentInfo contentInfo = new ContentInfo(data);
            SignedCms signedCms = new SignedCms(contentInfo, false);

            CmsSigner cmsSigner = new CmsSigner(certificate);
            cmsSigner.IncludeOption = X509IncludeOption.EndCertOnly;

            signedCms.ComputeSignature(cmsSigner);

            byte[] msgBytes = signedCms.Encode();
            return Convert.ToBase64String(msgBytes, Base64FormattingOptions.InsertLineBreaks);
        }

Unhandled exception. Internal.Cryptography.CryptoThrowHelper+WindowsCryptographicException: Keyset does not exist
   at Internal.NativeCrypto.CapiHelper.CreateProvHandle(CspParameters parameters, Boolean randomKeyContainer)
   at System.Security.Cryptography.Gost3410_2012_256CryptoServiceProvider.get_SafeProvHandle()
   at System.Security.Cryptography.Gost3410_2012_256CryptoServiceProvider.get_SafeKeyHandle()
   at System.Security.Cryptography.Gost3410_2012_256CryptoServiceProvider.GetKeyPair()
   at System.Security.Cryptography.Gost3410_2012_256CryptoServiceProvider..ctor(CspParameters parameters)
   at Internal.Cryptography.Pal.Windows.PkcsPalWindows.GetPrivateKey[T](X509Certificate2 certificate, Boolean silent, Boolean preferNCrypt) in C:\projects\corefx\src\System.Security.Cryptography.Pkcs\src\Internal\Cryptography\Pal\Windows\PkcsPalWindows.cs:line 285
   at Internal.Cryptography.Pal.Windows.PkcsPalWindows.GetPrivateKeyForSigning[T](X509Certificate2 certificate, Boolean silent) in C:\projects\corefx\src\System.Security.Cryptography.Pkcs\src\Internal\Cryptography\Pal\Windows\PkcsPalWindows.cs:line 181
   at System.Security.Cryptography.Pkcs.CmsSignature.Gost2012_256CmsSignature.Sign(ReadOnlySpan`1 dataHash, HashAlgorithmName hashAlgorithmName, X509Certificate2 certificate, AsymmetricAlgorithm key, Boolean silent, Oid& signatureAlgorithm, Byte[]& signatureValue) in C:\projects\corefx\src\System.Security.Cryptography.Pkcs\src\System\Security\Cryptography\Pkcs\CmsSignature.Gost2012_256.cs:line 71
   at System.Security.Cryptography.Pkcs.CmsSignature.Sign(ReadOnlySpan`1 dataHash, HashAlgorithmName hashAlgorithmName, X509Certificate2 certificate, AsymmetricAlgorithm key, Boolean silent, Oid& oid, ReadOnlyMemory`1& signatureValue) in C:\projects\corefx\src\System.Security.Cryptography.Pkcs\src\System\Security\Cryptography\Pkcs\CmsSignature.cs:line 104
   at System.Security.Cryptography.Pkcs.CmsSigner.Sign(ReadOnlyMemory`1 data, String contentTypeOid, Boolean silent, X509Certificate2Collection& chainCerts) in C:\projects\corefx\src\System.Security.Cryptography.Pkcs\src\System\Security\Cryptography\Pkcs\CmsSigner.cs:line 251
   at System.Security.Cryptography.Pkcs.SignedCms.ComputeSignature(CmsSigner signer, Boolean silent) in C:\projects\corefx\src\System.Security.Cryptography.Pkcs\src\System\Security\Cryptography\Pkcs\SignedCms.cs:line 323
   at System.Security.Cryptography.Pkcs.SignedCms.ComputeSignature(CmsSigner signer) in C:\projects\corefx\src\System.Security.Cryptography.Pkcs\src\System\Security\Cryptography\Pkcs\SignedCms.cs:line 274
   at DotnetSample.Program.SignData(Byte[] data, X509Certificate2 certificate) in D:\Projects\CryptoPro\DotnetCoreSampleProject\Program.cs:line 300
   at DotnetSample.Program.Main(String[] args) in D:\Projects\CryptoPro\DotnetCoreSampleProject\Program.cs:line 81

// The key handle is for CAPI.
                // Our CAPI types don't allow usage from a handle, so we have a few choices:
                // 1) Extract the information we need to re-open the key handle.
                // 2) Re-implement {R|D}SACryptoServiceProvider
                // 3) PNSE.
                // 4) Defer to cert.Get{R|D}SAPrivateKey if not silent, throw otherwise.
                CspParameters cspParams;

                try
                {
                    cspParams = handle.GetProvParameters();
                }

cspParams: {"Flags":"UseExistingKey","KeyPassword":null,"ParentWindowHandle":{}}

/// <summary>
        /// Конструктор алгоритма подписи по ГОСТ Р 34.10-2012 256.
        /// </summary>
        /// 
        /// <param name="parameters">Параметры алгоритма.</param>
        /// 
        /// <remarks><para>При создании контейнера без заданного имени
        /// контейнера и без указания флага использования контейнера по 
        /// умолчанию будет создано случайное имя, а создание ключей
        /// будет отложено, до его первого обращения.
        /// </para>
        /// 
        /// <para>При инициализации объекта через данный конструктор 
        /// будут использованы именно эти параметры, в независимости от
        /// флага <see cref="UseMachineKeyStore"/>. По умолчанию значение
        /// флага из 
        /// <see cref="Gost3410_2012_256CryptoServiceProvider(CspParameters)"/>
        /// устанавливется в использование ключей из хранилищи пользователя.
        /// Для использования ключей из хранилища компьютера 
        /// необходимо установить флаг <see cref="CspParameters.Flags"/>:
        /// <see cref="CspProviderFlags.UseMachineKeyStore"/>.
        /// </para>
        /// </remarks>
        /// 
        /// <containerperm flag="Open">Для открытия существующего 
        /// контейнера.</containerperm>
        /// <containerperm flag="Create">Для создания контейнера с заданным
        /// (не случайным именем).</containerperm>
        [SecuritySafeCritical]
        public Gost3410_2012_256CryptoServiceProvider(CspParameters parameters)

cspParams.Flags |= CspProviderFlags.UseMachineKeyStore;