(MFC) Get ECC Public Key in JWK Format (JSON Web Key)

Demonstrates how to get an ECC public key in JWK (JSON Web Key) format.

Note: This example requires Chilkat v9.5.0.66 or later.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkStringBuilder.h>
#include <CkPublicKey.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // Note: This example requires Chilkat v9.5.0.66 or later.

    // Load a PEM file into memory.
    CkStringBuilder sbPem;
    bool success = sbPem.LoadFile("qa_data/pem/ecc_public.pem","utf-8");
    if (success != true) {
        strOut.append("Failed to load PEM file.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Load the PEM into a public key object.
    CkPublicKey pubKey;
    success = pubKey.LoadFromString(sbPem.getAsString());
    if (success != true) {
        strOut.append(pubKey.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Get the public key in JWK format:
    const char *jwk = pubKey.getJwk();

    // The GetJwk method will return the JWK in the most compact JSON format possible,
    // as a single line with no extra whitespace.  To get a more human-readable JWK (for this example),
    // load into a Chilkat JSON object and emit non-compact:

    CkJsonObject json;
    json.Load(jwk);
    json.put_EmitCompact(false);
    strOut.append("ECC Public Key in JWK format:");
    strOut.append("\r\n");
    strOut.append(json.emit());
    strOut.append("\r\n");

    // Sample output:
    // { 
    //   "kty": "EC",
    //   "crv": "P-256",
    //   "x": "oBUyo8CQAFPeYPvv78ylh5MwFZjTCLQeb042TjiMJxE",
    //   "y": "vvQyxZkUjJQUPU_0bCy3Pj5qQdfu8jwEfqEeYGZ95CU"
    // }
    // 
    // Additional information can be added like this:
    json.AppendString("use","enc");
    json.AppendString("kid","123ABC");

    // Now examine the JSON:
    strOut.append(json.emit());
    strOut.append("\r\n");

    // { 
    //   "kty": "EC",
    //   "crv": "P-256",
    //   "x": "oBUyo8CQAFPeYPvv78ylh5MwFZjTCLQeb042TjiMJxE",
    //   "y": "vvQyxZkUjJQUPU_0bCy3Pj5qQdfu8jwEfqEeYGZ95CU",
    //   "use": "enc",
    //   "kid": "123ABC"
    // }


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }