C#

Get Public Key from CSR

See more CSR Examples

Demonstrates how to get the public key from a CSR. C#

bool success = false;

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

Chilkat.Pem pem = new Chilkat.Pem();

// No password is required.  Pass an empty password string..
string noPassword = "";
success = pem.LoadPemFile("qa_data/csr/csr2.pem",noPassword);
if (success != true) {
    Debug.WriteLine(pem.LastErrorText);
    return;
}

string strBase64 = pem.GetEncodedItem("csr","","base64",0);

Chilkat.Asn asn = new Chilkat.Asn();
success = asn.LoadEncoded(strBase64,"base64");
if (success != true) {
    Debug.WriteLine(asn.LastErrorText);
    return;
}

// Convert the ASN.1 to XML.
Chilkat.Xml xml = new Chilkat.Xml();
success = xml.LoadXml(asn.AsnToXml());
Debug.WriteLine(xml.GetXml());
Debug.WriteLine("----");

string strModulusHex = xml.GetChildContent("bits");
Debug.WriteLine("strModulusHex = " + strModulusHex);
Debug.WriteLine("----");

// We need the modulus as base64.
Chilkat.BinData bd = new Chilkat.BinData();
bd.AppendEncoded(strModulusHex,"hex");
string modulus64 = bd.GetEncoded("base64");
Debug.WriteLine("modulus64 = " + modulus64);
Debug.WriteLine("----");

// Build the XML for the public key.
Chilkat.Xml xmlPubKey = new Chilkat.Xml();
xmlPubKey.Tag = "RSAPublicKey";
xmlPubKey.UpdateChildContent("Modulus",modulus64);
// The RSA exponent will always be decimal 65537 (base64 = AQAB)
xmlPubKey.UpdateChildContent("Exponent","AQAB");

Debug.WriteLine("RSA public key as XML:");
Debug.WriteLine(xmlPubKey.GetXml());
Debug.WriteLine("----");

// Load the XML into a Chilkat public key object.
Chilkat.PublicKey pubkey = new Chilkat.PublicKey();
success = pubkey.LoadFromString(xmlPubKey.GetXml());
if (success != true) {
    Debug.WriteLine(pubkey.LastErrorText);
    return;
}

// Show the public key as PEM.
bool preferPkcs1 = true;
Debug.WriteLine(pubkey.GetPem(preferPkcs1));