(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.

Chilkat C/C++ Library Downloads
MS Visual C/C++ Linux/CentOS C/C++ Alpine Linux C/C++ MAC OS X C/C++	armhf/aarch64 C/C++ C++ Builder iOS C/C++ Android C/C++	Solaris C/C++ MinGW C/C++

#include <C_CkCert.h>
#include <C_CkPrivateKey.h>
#include <C_CkJsonObject.h>
#include <C_CkJws.h>
#include <C_CkPublicKey.h>

void ChilkatSample(void)
    {
    HCkCert cert;
    BOOL success;
    HCkPrivateKey privKey;
    HCkJsonObject jwsProtHdr;
    HCkJws jws;
    int signatureIndex;
    BOOL bIncludeBom;
    const char *payloadStr;
    const char *jwsCompact;
    HCkJws jws2;
    HCkPublicKey rsaPubKey;
    int v;
    HCkJsonObject 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 = CkCert_Create();
    success = CkCert_LoadFromSmartcard(cert,"");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkCert_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 = CkCert_ExportPrivateKey(cert);
    if (CkCert_getLastMethodSuccess(cert) == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkCert_Dispose(cert);
        return;
    }

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

    // Create the JWS Protected Header
    jwsProtHdr = CkJsonObject_Create();
    CkJsonObject_AppendString(jwsProtHdr,"alg","RS256");

    jws = CkJws_Create();

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

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

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

    // Create the JWS
    // By default, the compact serialization is used.
    jwsCompact = CkJws_createJws(jws);
    if (CkJws_getLastMethodSuccess(jws) != TRUE) {
        printf("%s\n",CkJws_lastErrorText(jws));
        CkPrivateKey_Dispose(privKey);
        CkCert_Dispose(cert);
        CkJsonObject_Dispose(jwsProtHdr);
        CkJws_Dispose(jws);
        return;
    }

    printf("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 = CkJws_Create();

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

    rsaPubKey = CkPrivateKey_GetPublicKey(privKey);
    CkPrivateKey_Dispose(privKey);

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

    // Validate the 1st (and only) signature at index 0..
    v = CkJws_Validate(jws2,signatureIndex);
    if (v < 0) {
        // Perhaps Chilkat was not unlocked or the trial expired..
        printf("Method call failed for some other reason.\n");
        printf("%s\n",CkJws_lastErrorText(jws2));
        CkCert_Dispose(cert);
        CkJsonObject_Dispose(jwsProtHdr);
        CkJws_Dispose(jws);
        CkJws_Dispose(jws2);
        return;
    }

    if (v == 0) {
        printf("Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both.\n");
        CkCert_Dispose(cert);
        CkJsonObject_Dispose(jwsProtHdr);
        CkJws_Dispose(jws);
        CkJws_Dispose(jws2);
        return;
    }

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

    // Recover the original content:
    printf("%s\n",CkJws_getPayload(jws2,"utf-8"));

    // Examine the protected header:
    joseHeader = CkJws_GetProtectedHeader(jws2,signatureIndex);
    if (CkJws_getLastMethodSuccess(jws2) != TRUE) {
        printf("No protected header found at the given index.\n");
        CkCert_Dispose(cert);
        CkJsonObject_Dispose(jwsProtHdr);
        CkJws_Dispose(jws);
        CkJws_Dispose(jws2);
        return;
    }

    CkJsonObject_putEmitCompact(joseHeader,FALSE);

    printf("Protected (JOSE) header:\n");
    printf("%s\n",CkJsonObject_emit(joseHeader));
    CkJsonObject_Dispose(joseHeader);

    // Output:

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


    CkCert_Dispose(cert);
    CkJsonObject_Dispose(jwsProtHdr);
    CkJws_Dispose(jws);
    CkJws_Dispose(jws2);

    }