using System;

using System.Security.Cryptography;

using System.Text;

​

public class HashCalculator

{

    public string ComputeHash(string secret, string payload)

    {

        using (var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(secret)))

        {

            byte[] hashBytes = hmac.ComputeHash(Encoding.UTF8.GetBytes(payload));

            return Convert.ToBase64String(hashBytes);

        }

    }

}

​

public class Program

{

    public static void Main()

    {       

        HashCalculator calculator = new HashCalculator();

        long timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();

        string secret = "suaApiSecret";

        string payload = "{\"cpfResponsavel\":\"99804464047\",\"beneficiarios\":[{\"entrevistaID\":\"14111887\",\"cpfBeneficiario\":\"99804464047\",\"status\":\"FENTREVISTA\",\"documentos\":[{\"conteudoArquivo\":\"teste de conteudo de arquivo\",\"nomeArquivo\":\"162 - Entrevista Qualificada - Unimed SJC - UNIMED SÃO JOSÉ DOS CAMPOS COOPERATIVA DE TRABALHO MÉDICO - GABRIEL COELHO DE SOUZA.pdf\"}]}],\"timestamp\":"+ timestamp +"}";

        string hash = calculator.ComputeHash(secret, payload);

​

        Console.WriteLine(payload);

        Console.WriteLine(hash);

    }

}