(C++) Create JWS Using Private Key on a Smart Card

See more JSON Web Signatures (JWS) Examples

Creates and validates a JSON Web Signature (JWS) using the private key associated with a certificate on a smart card.

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#include <CkCert.h>
#include <CkPrivateKey.h>
#include <CkJsonObject.h>
#include <CkJws.h>
#include <CkPublicKey.h>

void ChilkatSample(void)
    {
    // This requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Load the certificate from a smart card.
    CkCert cert;
    bool success = cert.LoadFromSmartcard("");
    if (success == false) {
        std::cout << cert.lastErrorText() << "\r\n";
        return;
    }

    // Note: Chilkat provides many different ways to load a certificate from a smartcard or USB token,
    // such as selecting a certificate if the card contains multiple certificates with private keys,
    // or working with lower-level PKCS11 or ScMinidriver API's (both of which Chilkat provides).

    // If the associated private key was present on the smartcard, then you can simply
    // get it from the Chilkat cert object:
    CkPrivateKey *privKey = cert.ExportPrivateKey();
    if (cert.get_LastMethodSuccess() == false) {
        std::cout << cert.lastErrorText() << "\r\n";
        return;
    }

    // You can check the key type to make sure it's RSA.
    // This will output "rsa" if the key is RSA.
    std::cout << "Key type = " << privKey->keyType() << "\r\n";

    // Create the JWS Protected Header
    CkJsonObject jwsProtHdr;
    jwsProtHdr.AppendString("alg","RS256");

    CkJws jws;

    // Set the protected header:
    int signatureIndex = 0;
    jws.SetProtectedHeader(signatureIndex,jwsProtHdr);

    // Set the RSA key:
    jws.SetPrivateKey(signatureIndex,*privKey);

    // Set the payload.
    bool bIncludeBom = false;
    const char *payloadStr = "In our village, folks say God crumbles up the old moon into stars.";
    jws.SetPayload(payloadStr,"utf-8",bIncludeBom);

    // Create the JWS
    // By default, the compact serialization is used.
    const char *jwsCompact = jws.createJws();
    if (jws.get_LastMethodSuccess() != true) {
        std::cout << jws.lastErrorText() << "\r\n";
        delete privKey;
        return;
    }

    std::cout << "JWS: " << jwsCompact << "\r\n";

    // sample output:
    // JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

    // Now load the JWS, validate, and recover the original text.
    CkJws jws2;

    // Load the JWS.
    success = jws2.LoadJws(jwsCompact);

    CkPublicKey *rsaPubKey = privKey->GetPublicKey();
    delete privKey;

    // Set the RSA public key used for validation.
    signatureIndex = 0;
    jws2.SetPublicKey(signatureIndex,*rsaPubKey);
    delete rsaPubKey;

    // Validate the 1st (and only) signature at index 0..
    int v = jws2.Validate(signatureIndex);
    if (v < 0) {
        // Perhaps Chilkat was not unlocked or the trial expired..
        std::cout << "Method call failed for some other reason." << "\r\n";
        std::cout << jws2.lastErrorText() << "\r\n";
        return;
    }

    if (v == 0) {
        std::cout << "Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both." << "\r\n";
        return;
    }

    // If we get here, the signature was validated..
    std::cout << "Signature validated." << "\r\n";

    // Recover the original content:
    std::cout << jws2.getPayload("utf-8") << "\r\n";

    // Examine the protected header:
    CkJsonObject *joseHeader = jws2.GetProtectedHeader(signatureIndex);
    if (jws2.get_LastMethodSuccess() != true) {
        std::cout << "No protected header found at the given index." << "\r\n";
        return;
    }

    joseHeader->put_EmitCompact(false);

    std::cout << "Protected (JOSE) header:" << "\r\n";
    std::cout << joseHeader->emit() << "\r\n";
    delete joseHeader;

    // Output:

    // 	Signature validated.
    // 	In our village, folks say God crumbles up the old moon into stars.
    // 	Protected (JOSE) header:
    // 	{ 
    // 	  "alg": "RS256"
    // 	}
    }