openssl pkcs12 -export -in cer.pem -inkey cer.key -out сer.p12 -engine gost -keypbe gost89 -certpbe gost89

CheckSignature()

 Sub Main(args As String())
        Console.OutputEncoding = Encoding.UTF8
        Console.InputEncoding = Encoding.UTF8
        If args.Length < 2 Then
            Console.WriteLine("Xml.Verify <document> ...")
            Return
        End If
        'xml File to sign
        Dim xmlFileData As String = args(0)
        'signed xml file
        Dim xmlFileSigned As String = xmlFileData + "_SignedXml.xml"
        Try
            ' Find certificate in local store
            Dim store As X509Store = New X509Store("My", StoreLocation.CurrentUser)
            store.Open(OpenFlags.OpenExistingOnly Or OpenFlags.ReadOnly)
            Dim found As X509Certificate2Collection =
                store.Certificates.Find(X509FindType.FindBySubjectName,
                args(2), False)

            ' Check if one
            If found.Count = 0 Then
                Console.WriteLine("Certificate not found.")
                Return
            End If
            If found.Count > 1 Then
                Console.WriteLine("There was found more than one certificates.")
                Return
            End If
            Dim Certificate As X509Certificate2 = found(0)
            ' Open private key.
            Dim Key As AsymmetricAlgorithm = Certificate.PrivateKey
            
            Console.WriteLine("Signing: {0}", xmlFileData)

            'Create detach sign and save it to the file
            SignDetachedXML(xmlFileData, xmlFileSigned, Certificate, Key)

            Console.WriteLine("xml file was signed")
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try

    End Sub

    Sub SignDetachedXML(xmlData As String, xmlFileSignature As String, cer As X509Certificate2, Key As AsymmetricAlgorithm)
        'create a SignedXml object
        Dim xmlDocument As XmlDocument = New XmlDocument()
        xmlDocument.PreserveWhitespace = True

        xmlDocument.Load(xmlData)
        Dim SignedXML_ As SignedXml = New SignedXml(xmlDocument)

        'Add key to signed xml
        SignedXML_.SigningKey = Key

        'Add the reference to signed xml
        Dim ref As Reference = New Reference()
        ref.Uri = ""
        'Digest method
        ref.DigestMethod = CPSignedXml.XmlDsigGost3411_2012_256Url
        ' Transform for canonicalization
        Dim c14 As XmlDsigExcC14NWithCommentsTransform = New XmlDsigExcC14NWithCommentsTransform()
        ref.AddTransform(c14)
        SignedXML_.AddReference(ref)


        'Add keyInfo to signed xml
        Dim keyinfo_ As KeyInfo = New KeyInfo()
        'keyinfo_.AddClause(New RSAKeyValue(key))
        Dim keyInfoData As KeyInfoX509Data = New KeyInfoX509Data(cer)
        keyinfo_.AddClause(keyInfoData)
        SignedXML_.KeyInfo = keyinfo_

        'Set canonicalization as c14n#WithComments
        SignedXML_.SignedInfo.CanonicalizationMethod = SignedXml.XmlDsigExcC14NWithCommentsTransformUrl
        'Set gost-2012-256 signing method
        SignedXML_.SignedInfo.SignatureMethod = CPSignedXml.XmlDsigGost3410_2012_256Url

        'Compute signature
        SignedXML_.ComputeSignature()

        'Create and save xml file with Signature
        Dim XmlSignatureFIle As XmlElement = SignedXML_.GetXml()

        Dim xmltw As XmlTextWriter = New XmlTextWriter(xmlFileSignature, New UTF8Encoding(False))
        XmlSignatureFIle.WriteTo(xmltw)
        xmltw.Close()


    End Sub

CheckSignature()

CheckSignature()

openssl dgst -md_gost12_256 -pverify privatekey.key \
        -signature signature.sign \
        input_file
#privatekey.pem - закрытый ключ
#signature.sign - рассчитанное ранее значение сигнатуры для проверки
#input_file - файл, для которого ранее вычислялось signature

openssl dgst -sign private_key -binary -md_gost12_256 digest_value 
#private_key - ключ, digest_value - полученное ранее значение digest

openssl dgst -sign private_key -binary -md_gost12_256 canonicalizated.xml 
#private_key - закрытый ключ, canonicalizated.xml  - xml файл, для которого вычисляется signature, в канонической форме

CheckSignature()