(.NET Core C#) Sign Mexico Pedimento

Add a signature to a Mexico pedimento file.

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

bool success;

// This is the contents before signing:

// 500|1|3621|4199800|400||
// 601|3621|4199800|400|IN|1||EKU9003173C9|EKU9003173C9FRNN09|1||
// 507|4199800|IM|2006-7888">
// 507|4199800|MS|2">
// 800|4199800|1">
// 801|M3621037.222|1|5|011|

// This is the contents after signing

// 500|1|3621|4199800|400||
// 601|3621|4199800|400|IN|1||EKU9003173C9|EKU9003173C9FRNN09|1||
// 507|4199800|IM|2006-7888">
// 507|4199800|MS|2">
// 800|4199800|1|fhP2Ker54D2+3+UZch23F0E72 .... 9qNSPIuAqpj524qLZbbA==|30001000000500003416|
// 801|M3621037.222|1|5|011|

// First create the text to be signed.
bool bCRLF = true;
Chilkat.StringBuilder sb = new Chilkat.StringBuilder();
// Use CRLF line endings.
sb.AppendLine("500|1|3621|4199800|400||",bCRLF);
sb.AppendLine("601|3621|4199800|400|IN|1||EKU9003173C9|EKU9003173C9FRNN09|1||",bCRLF);
sb.AppendLine("507|4199800|IM|2006-7888">",bCRLF);
sb.AppendLine("507|4199800|MS|2">",bCRLF);

// Generate the MD5 hash of what we have so far..
string md5_base64 = sb.GetHash("md5","base64","utf-8");
Debug.WriteLine("MD5 hash = " + md5_base64);

// Complete the original file.
// After signing, we'll update the BASE64_SIGNATURE and CERT_SERIAL
sb.AppendLine("800|4199800|1|BASE64_SIGNATURE|CERT_SERIAL|",bCRLF);
sb.AppendLine("801|M3621037.222|1|5|011|",bCRLF);

// We're going to sign the MD5 hash using the private key.
Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();
success = privKey.LoadAnyFormatFile("qa_data/certs/mexico_test/Certificados_de_Prueba/Certificados_Pruebas/Personas Morales/EKU9003173C9_20230517223532/CSD_EKU9003173C9_20230517223903/CSD_Sucursal_1_EKU9003173C9_20230517_223850.key","12345678a");
if (success == false) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

// Generate the ASN.1 to be signed.

// <sequence>
//     <sequence>
//         <oid>1.2.840.113549.2.5</oid>
//         <null/>
//     </sequence>
//     <octets>SwxHfaJhG+N3pPqay6UzVA==</octets>
// </sequence>

Chilkat.Xml xml = new Chilkat.Xml();
xml.Tag = "sequence";
xml.UpdateChildContent("sequence|oid","1.2.840.113549.2.5");
xml.UpdateChildContent("sequence|null","");
xml.UpdateChildContent("octets",md5_base64);

Chilkat.Asn asn = new Chilkat.Asn();
asn.LoadAsnXml(xml.GetXml());
Debug.WriteLine("ASN.1 = " + asn.GetEncodedDer("base64"));

// Sign with the private key.
Chilkat.Rsa rsa = new Chilkat.Rsa();
success = rsa.ImportPrivateKeyObj(privKey);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// Create the opaque signature.
Chilkat.BinData bdSig = new Chilkat.BinData();
bdSig.AppendEncoded(asn.GetEncodedDer("base64"),"base64");
success = rsa.OpenSslSignBd(bdSig);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// bd now contains the opaque signature, which embeds the ASN.1, which contains the MD5 hash.
// We're going to add this line:
// 800|4199800|1|BASE64_SIGNATURE|CERT_SERIAL_NUM|

Chilkat.Cert cert = new Chilkat.Cert();
success = cert.LoadFromFile("qa_data/certs/mexico_test/Certificados_de_Prueba/Certificados_Pruebas/Personas Morales/EKU9003173C9_20230517223532/CSD_EKU9003173C9_20230517223903/CSD_Sucursal_1_EKU9003173C9_20230517_223850.cer");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

string serialHex = cert.SerialNumber;
// The serial in hex form looks like this:   3330303031303030303030353030303033343136
// Decode to us-ascii.
Chilkat.StringBuilder sbSerial = new Chilkat.StringBuilder();
sbSerial.DecodeAndAppend(serialHex,"hex","us-ascii");
Debug.WriteLine("serial number in us-ascii: " + sbSerial.GetAsString());

int numReplaced = sb.Replace("CERT_SERIAL",sbSerial.GetAsString());
numReplaced = sb.Replace("BASE64_SIGNATURE",bdSig.GetEncoded("base64"));

Debug.WriteLine("------------------------------------");
Debug.WriteLine("Result:");
Debug.WriteLine(sb.GetAsString());