(C#) Get ETK Public Key (api-acpt.ehealth.fgov.be)

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The following URL returns JSON, which contains a PKCS7 signed data:

https://api-acpt.ehealth.fgov.be/etee/v1/etks?identifier=12345678901&type=SSIN

This example extracts the signed data, validates it, and then extracts the public key from the certificate (obtained from signed content in the PKCS7)

Note: The URL above uses "12345678901" which is not valid. You should replace it with a valid number.

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

Chilkat.Http http = new Chilkat.Http();

string jsonStr = http.QuickGetStr("https://api-acpt.ehealth.fgov.be/etee/v1/etks?identifier=12345678901&type=SSIN");
if (http.LastMethodSuccess == false) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

Debug.WriteLine(jsonStr);

// The JSON contains something like this:

// [
//     {
//         "key": {
//             "applicationIdentifier": "",
//             "ssin": "12345678901"
//         },
//         "value": "MIAGCSq....AAAAAAAA=="
//     }
// ]

// Note: The above is a JSON array (not a JSON object)
// It should be loaded into a Chilkat JSON array.
Chilkat.JsonArray jarr = new Chilkat.JsonArray();
bool success = jarr.Load(jsonStr);
if (success == false) {
    Debug.WriteLine("Failed to load JSON.");
    return;
}

Chilkat.JsonObject json = jarr.ObjectAt(0);
Chilkat.BinData bdPkcs7 = new Chilkat.BinData();
bdPkcs7.AppendEncoded(json.StringOf("value"),"base64");

// Let's verify the PKCS7, and then examine the signing cert,
// and get the signing cert's public key.
Chilkat.Crypt2 crypt = new Chilkat.Crypt2();

// Validate the signedData PKCS7, and replace the contents of bdPkcs7 with the extracted signed content.
success = crypt.OpaqueVerifyBd(bdPkcs7);
if (success == false) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

// The signed content is the DER of a certificate.
// In other words, bdPkcs7 now contains a certificate.
Chilkat.Cert cert = new Chilkat.Cert();
success = cert.LoadFromBd(bdPkcs7);
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Show some certificate information:
Debug.WriteLine("Subject: " + cert.SubjectDN);
Debug.WriteLine("Serial: " + cert.SerialNumber);
Debug.WriteLine("Issuer: " + cert.IssuerDN);

// Let's get the cert's public key...
Chilkat.PublicKey pubKey = cert.ExportPublicKey();
if (cert.LastMethodSuccess == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// OK, you now have the public key and can do whatever is needed..
Debug.WriteLine(pubKey.KeyType);
Debug.WriteLine(Convert.ToString(pubKey.KeySize));