Alternative function for PEM_read_bio_PUBKEY that reads key from .crt file

Question

I am curently using this function: PEM_read_bio_PUBKEY to read a public key. Is there any alternative function that instead of a PEM file you can read the key from a X509 crt file?

Answer 1

I found a solution by debuging the openssl cli util: I downloaded the openssl code and debuged it with the folowing args: x509 -in E:/mycert.crt -pubkey -out E:/mypubkey.pem

static EVP_PKEY *getPubKeyFromCRT(const char *filename) {
    EVP_PKEY *pubkey = NULL;
    X509_STORE *ctx_store = NULL;
    X509 *x509_crt = NULL;

    ctx_store = X509_STORE_new();
    //TODO ERROR HANDLING

    X509_STORE_set_verify_cb(ctx_store, callback_verify_cert);

    if(!X509_STORE_set_default_paths(ctx_store)) {
        //TODO ERROR HANDLING
    }

    x509_crt = getCertFromCRTFile(filename);
    //TODO ERROR HANDLING

    pubkey = X509_get_pubkey(x509_crt);
}