C

Validate a JWS Using ECDSA P-521 SHA-512

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) that uses ECDSA P-521 SHA-512 C

#include <C_CkStringBuilder.h>
#include <C_CkPublicKey.h>
#include <C_CkJws.h>
#include <C_CkJsonObject.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkStringBuilder sbPubKey;
    HCkPublicKey pubKey;
    HCkJws jws;
    int signatureIndex;
    HCkStringBuilder sbJws;
    int v;
    HCkJsonObject joseHeader;

    success = FALSE;

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

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

    //  We only need a public key for signature validation.  This is the ECDSA public key
    //  that is used:

    //       {"kty":"EC", 
    //        "crv":"P-521", 
    //        "x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk", 
    //        "y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDly79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2" 
    //       } 

    sbPubKey = CkStringBuilder_Create();
    CkStringBuilder_Append(sbPubKey,"{\"kty\":\"EC\",");
    CkStringBuilder_Append(sbPubKey,"\"crv\":\"P-521\",");
    CkStringBuilder_Append(sbPubKey,"\"x\":\"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk\",");
    CkStringBuilder_Append(sbPubKey,"\"y\":\"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDly79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2\"");
    CkStringBuilder_Append(sbPubKey,"}");

    pubKey = CkPublicKey_Create();
    success = CkPublicKey_LoadFromString(pubKey,CkStringBuilder_getAsString(sbPubKey));
    if (success == FALSE) {
        printf("%s\n",CkPublicKey_lastErrorText(pubKey));
        CkStringBuilder_Dispose(sbPubKey);
        CkPublicKey_Dispose(pubKey);
        return;
    }

    jws = CkJws_Create();

    //  Set the ECC public key:
    signatureIndex = 0;
    CkJws_SetPublicKey(jws,signatureIndex,pubKey);

    //  Load the JWS.
    sbJws = CkStringBuilder_Create();
    CkStringBuilder_Append(sbJws,"eyJhbGciOiJFUzUxMiJ9");
    CkStringBuilder_Append(sbJws,".");
    CkStringBuilder_Append(sbJws,"UGF5bG9hZA");
    CkStringBuilder_Append(sbJws,".");
    CkStringBuilder_Append(sbJws,"AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq");
    CkStringBuilder_Append(sbJws,"wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp");
    CkStringBuilder_Append(sbJws,"EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn");

    success = CkJws_LoadJwsSb(jws,sbJws);
    if (success == FALSE) {
        printf("%s\n",CkJws_lastErrorText(jws));
        CkStringBuilder_Dispose(sbPubKey);
        CkPublicKey_Dispose(pubKey);
        CkJws_Dispose(jws);
        CkStringBuilder_Dispose(sbJws);
        return;
    }

    //  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));
        CkStringBuilder_Dispose(sbPubKey);
        CkPublicKey_Dispose(pubKey);
        CkJws_Dispose(jws);
        CkStringBuilder_Dispose(sbJws);
        return;
    }

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

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

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

    //  Examine the protected header:

    joseHeader = CkJsonObject_Create();
    success = CkJws_GetProtectedH(jws,signatureIndex,joseHeader);
    if (success == FALSE) {
        printf("%s\n",CkJws_lastErrorText(jws));
        CkStringBuilder_Dispose(sbPubKey);
        CkPublicKey_Dispose(pubKey);
        CkJws_Dispose(jws);
        CkStringBuilder_Dispose(sbJws);
        CkJsonObject_Dispose(joseHeader);
        return;
    }

    CkJsonObject_putEmitCompact(joseHeader,FALSE);

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

    //  Output:
    //  (the string "Payload" was the content that was signed.)

    //  	Signature validated.
    //  	--
    //  	Recovered content:
    //  	Payload
    //  	--
    //  	Protected (JOSE) header:
    //  	{
    //  	  "alg": "ES512"
    //  	}


    CkStringBuilder_Dispose(sbPubKey);
    CkPublicKey_Dispose(pubKey);
    CkJws_Dispose(jws);
    CkStringBuilder_Dispose(sbJws);
    CkJsonObject_Dispose(joseHeader);

    }