<?xml version="1.0"?>
<Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
<SignedInfo>
<CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
<SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#gostr34102001-gostr3411"/>
<Reference URI="#Object1">
<DigestMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#gostr3411"/>
<DigestValue></DigestValue>
</Reference>
</SignedInfo>
<SignatureValue></SignatureValue>
<KeyInfo>
<X509Data>
<X509Certificate></X509Certificate>
</X509Data>
</KeyInfo><Object Id="Object1"/></Signature>

var oSigner = new CPSigner
{
   Certificate = <сертификат, алгоритм хэширования GOST R 34.11-94>,
   TSAAddress = "http://cryptopro.ru/tsp/",
};

var oSignedXml = new SignedXML
{
   SignatureType = CADESCOM_XML_SIGNATURE_TYPE.CADESCOM_XML_SIGNATURE_TYPE_TEMPLATE,
   Content = <xml документ в виде строки>
};

return oSignedXml.Sign(oSigner);

var oHashedData = new CPHashedData
{
    Algorithm = (CAPICOM_HASH_ALGORITHM)CADESCOM_HASH_ALGORITHM.CADESCOM_HASH_ALGORITHM_CP_GOST_3411
};
oHashedData.Hash("<Object xmlns=\"http://www.w3.org/2000/09/xmldsig#\" Id=\"Object1\"></Object>");  // формат c14n

byte[] bytes = HexStringToByteArray(oHashedData.Value);    // Шестрадцатиричное значение в байт-массив
string base64String = Convert.ToBase64String(bytes);

return base64String;

        /// <param name="value">Строка в UTF-8</param>
        /// <returns>hex значение хэша</returns>
        public string GetHashByString(string value)
        {
            try
            {
                var oHashedData = new CPHashedData
                {
                    Algorithm = (CAPICOM_HASH_ALGORITHM)CADESCOM_HASH_ALGORITHM.CADESCOM_HASH_ALGORITHM_CP_GOST_3411,
                    DataEncoding = CADESCOM_CONTENT_ENCODING_TYPE.CADESCOM_BASE64_TO_BINARY
                };

                //надо перевести в base64 
                var byteValue = Encoding.UTF8.GetBytes(value);
                var base64Value = Convert.ToBase64String(byteValue);
                oHashedData.Hash(base64Value);
                                
                return oHashedData.Value;
            }
            catch (Exception ex)
            {
                SaveLogInfo("GetHashByString" + Environment.NewLine, ex);
                throw;
            }
        }