(Unicode 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 <C_CkCertW.h>
#include <C_CkPrivateKeyW.h>
#include <C_CkJsonObjectW.h>
#include <C_CkJwsW.h>
#include <C_CkPublicKeyW.h>

void ChilkatSample(void)
    {
    HCkCertW cert;
    BOOL success;
    HCkPrivateKeyW privKey;
    HCkJsonObjectW jwsProtHdr;
    HCkJwsW jws;
    int signatureIndex;
    BOOL bIncludeBom;
    const wchar_t *payloadStr;
    const wchar_t *jwsCompact;
    HCkJwsW jws2;
    HCkPublicKeyW rsaPubKey;
    int v;
    HCkJsonObjectW joseHeader;

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

    // Load the certificate from a smart card.
    cert = CkCertW_Create();
    success = CkCertW_LoadFromSmartcard(cert,L"");
    if (success == FALSE) {
        wprintf(L"%s\n",CkCertW_lastErrorText(cert));
        CkCertW_Dispose(cert);
        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:
    privKey = CkCertW_ExportPrivateKey(cert);
    if (CkCertW_getLastMethodSuccess(cert) == FALSE) {
        wprintf(L"%s\n",CkCertW_lastErrorText(cert));
        CkCertW_Dispose(cert);
        return;
    }

    // You can check the key type to make sure it's RSA.
    // This will output "rsa" if the key is RSA.
    wprintf(L"Key type = %s\n",CkPrivateKeyW_keyType(privKey));

    // Create the JWS Protected Header
    jwsProtHdr = CkJsonObjectW_Create();
    CkJsonObjectW_AppendString(jwsProtHdr,L"alg",L"RS256");

    jws = CkJwsW_Create();

    // Set the protected header:
    signatureIndex = 0;
    CkJwsW_SetProtectedHeader(jws,signatureIndex,jwsProtHdr);

    // Set the RSA key:
    CkJwsW_SetPrivateKey(jws,signatureIndex,privKey);

    // Set the payload.
    bIncludeBom = FALSE;
    payloadStr = L"In our village, folks say God crumbles up the old moon into stars.";
    CkJwsW_SetPayload(jws,payloadStr,L"utf-8",bIncludeBom);

    // Create the JWS
    // By default, the compact serialization is used.
    jwsCompact = CkJwsW_createJws(jws);
    if (CkJwsW_getLastMethodSuccess(jws) != TRUE) {
        wprintf(L"%s\n",CkJwsW_lastErrorText(jws));
        CkPrivateKeyW_Dispose(privKey);
        CkCertW_Dispose(cert);
        CkJsonObjectW_Dispose(jwsProtHdr);
        CkJwsW_Dispose(jws);
        return;
    }

    wprintf(L"JWS: %s\n",jwsCompact);

    // 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.
    jws2 = CkJwsW_Create();

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

    rsaPubKey = CkPrivateKeyW_GetPublicKey(privKey);
    CkPrivateKeyW_Dispose(privKey);

    // Set the RSA public key used for validation.
    signatureIndex = 0;
    CkJwsW_SetPublicKey(jws2,signatureIndex,rsaPubKey);
    CkPublicKeyW_Dispose(rsaPubKey);

    // Validate the 1st (and only) signature at index 0..
    v = CkJwsW_Validate(jws2,signatureIndex);
    if (v < 0) {
        // Perhaps Chilkat was not unlocked or the trial expired..
        wprintf(L"Method call failed for some other reason.\n");
        wprintf(L"%s\n",CkJwsW_lastErrorText(jws2));
        CkCertW_Dispose(cert);
        CkJsonObjectW_Dispose(jwsProtHdr);
        CkJwsW_Dispose(jws);
        CkJwsW_Dispose(jws2);
        return;
    }

    if (v == 0) {
        wprintf(L"Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both.\n");
        CkCertW_Dispose(cert);
        CkJsonObjectW_Dispose(jwsProtHdr);
        CkJwsW_Dispose(jws);
        CkJwsW_Dispose(jws2);
        return;
    }

    // If we get here, the signature was validated..
    wprintf(L"Signature validated.\n");

    // Recover the original content:
    wprintf(L"%s\n",CkJwsW_getPayload(jws2,L"utf-8"));

    // Examine the protected header:
    joseHeader = CkJwsW_GetProtectedHeader(jws2,signatureIndex);
    if (CkJwsW_getLastMethodSuccess(jws2) != TRUE) {
        wprintf(L"No protected header found at the given index.\n");
        CkCertW_Dispose(cert);
        CkJsonObjectW_Dispose(jwsProtHdr);
        CkJwsW_Dispose(jws);
        CkJwsW_Dispose(jws2);
        return;
    }

    CkJsonObjectW_putEmitCompact(joseHeader,FALSE);

    wprintf(L"Protected (JOSE) header:\n");
    wprintf(L"%s\n",CkJsonObjectW_emit(joseHeader));
    CkJsonObjectW_Dispose(joseHeader);

    // Output:

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


    CkCertW_Dispose(cert);
    CkJsonObjectW_Dispose(jwsProtHdr);
    CkJwsW_Dispose(jws);
    CkJwsW_Dispose(jws2);

    }