(C) 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++ 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_CkJws.h>
#include <C_CkJsonObject.h>

void ChilkatSample(void)
    {
    HCkJws jws;
    const char *hmacKey;
    int signatureIndex;
    const char *jwsCompact;
    BOOL success;
    int v;
    HCkJsonObject joseHeader;

    // 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.

    jws = CkJws_Create();

    // Set the HMAC key:
    hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow";
    signatureIndex = 0;
    CkJws_SetMacKey(jws,signatureIndex,hmacKey,"base64url");

    // Load the JWS.
    jwsCompact = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
    success = CkJws_LoadJws(jws,jwsCompact);

    // Validate the 1st (and only) signature at index 0..
    v = CkJws_Validate(jws,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(jws));
        CkJws_Dispose(jws);
        return;
    }

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

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

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

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

    CkJsonObject_putEmitCompact(joseHeader,FALSE);

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

    // Output:

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


    CkJws_Dispose(jws);

    }