(MFC) Validate JWS Using HMAC SHA-256

Validates a JSON Web Signature (JWS) using HMAC SHA-256.

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

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

See Also: Using MFC CString in Chilkat

#include <CkJws.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

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

    // This example takes a JSON signature in compact serialization format,
    // and uses a MAC key to validate and recover the protected header and payload.

    CkJws jws;

    // Set the HMAC key:
    const char *hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow";
    int signatureIndex = 0;
    jws.SetMacKey(signatureIndex,hmacKey,"base64url");

    // Load the JWS.
    const char *jwsCompact = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
    bool success = jws.LoadJws(jwsCompact);

    // Validate the 1st (and only) signature at index 0..
    int v = jws.Validate(signatureIndex);
    if (v < 0) {
        // Perhaps Chilkat was not unlocked or the trial expired..
        strOut.append("Method call failed for some other reason.");
        strOut.append("\r\n");
        strOut.append(jws.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    if (v == 0) {
        strOut.append("Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // If we get here, the signature was validated..
    strOut.append("Signature validated.");
    strOut.append("\r\n");

    // Recover the original content:
    strOut.append("Recovered content:");
    strOut.append("\r\n");
    strOut.append(jws.getPayload("utf-8"));
    strOut.append("\r\n");

    // Examine the protected header:
    CkJsonObject *joseHeader = jws.GetProtectedHeader(signatureIndex);
    if (jws.get_LastMethodSuccess() != true) {
        strOut.append("No protected header found at the given index.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    joseHeader->put_EmitCompact(false);

    strOut.append("Protected (JOSE) header:");
    strOut.append("\r\n");
    strOut.append(joseHeader->emit());
    strOut.append("\r\n");
    delete joseHeader;

    // Output:

    // 	Signature validated.
    // 	Recovered content:
    // 	{"iss":"joe",
    // 	 "exp":1300819380,
    // 	 "http://example.com/is_root":true}
    // 	Protected (JOSE) header:
    // 	{ 
    // 	  "typ": "JWT",
    // 	  "alg": "HS256"
    // 	}


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }