(C) Get ECC Public Key in JWK Format (JSON Web Key)

Demonstrates how to get an ECC public key in JWK (JSON Web Key) format.

Note: This example requires Chilkat v9.5.0.66 or later.

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

void ChilkatSample(void)
    {
    HCkStringBuilder sbPem;
    BOOL success;
    HCkPublicKey pubKey;
    const char *jwk;
    HCkJsonObject json;

    // Note: This example requires Chilkat v9.5.0.66 or later.

    // Load a PEM file into memory.
    sbPem = CkStringBuilder_Create();
    success = CkStringBuilder_LoadFile(sbPem,"qa_data/pem/ecc_public.pem","utf-8");
    if (success != TRUE) {
        printf("Failed to load PEM file.\n");
        CkStringBuilder_Dispose(sbPem);
        return;
    }

    // Load the PEM into a public key object.
    pubKey = CkPublicKey_Create();
    success = CkPublicKey_LoadFromString(pubKey,CkStringBuilder_getAsString(sbPem));
    if (success != TRUE) {
        printf("%s\n",CkPublicKey_lastErrorText(pubKey));
        CkStringBuilder_Dispose(sbPem);
        CkPublicKey_Dispose(pubKey);
        return;
    }

    // Get the public key in JWK format:
    jwk = CkPublicKey_getJwk(pubKey);

    // The GetJwk method will return the JWK in the most compact JSON format possible,
    // as a single line with no extra whitespace.  To get a more human-readable JWK (for this example),
    // load into a Chilkat JSON object and emit non-compact:

    json = CkJsonObject_Create();
    CkJsonObject_Load(json,jwk);
    CkJsonObject_putEmitCompact(json,FALSE);
    printf("ECC Public Key in JWK format:\n");
    printf("%s\n",CkJsonObject_emit(json));

    // Sample output:
    // { 
    //   "kty": "EC",
    //   "crv": "P-256",
    //   "x": "oBUyo8CQAFPeYPvv78ylh5MwFZjTCLQeb042TjiMJxE",
    //   "y": "vvQyxZkUjJQUPU_0bCy3Pj5qQdfu8jwEfqEeYGZ95CU"
    // }
    // 
    // Additional information can be added like this:
    CkJsonObject_AppendString(json,"use","enc");
    CkJsonObject_AppendString(json,"kid","123ABC");

    // Now examine the JSON:
    printf("%s\n",CkJsonObject_emit(json));

    // { 
    //   "kty": "EC",
    //   "crv": "P-256",
    //   "x": "oBUyo8CQAFPeYPvv78ylh5MwFZjTCLQeb042TjiMJxE",
    //   "y": "vvQyxZkUjJQUPU_0bCy3Pj5qQdfu8jwEfqEeYGZ95CU",
    //   "use": "enc",
    //   "kid": "123ABC"
    // }


    CkStringBuilder_Dispose(sbPem);
    CkPublicKey_Dispose(pubKey);
    CkJsonObject_Dispose(json);

    }