verify_demo.cc

int verify(uint8_t *msg, size_t msglen, uint8_t *signature, size_t signature_len, std::string sha_alg)
{
    if (!msg || !signature) {
        std::cerr << "invalid msg or signature" << std::endl;
        return -1;
    }

    const EVP_MD *md;

    if (sha_alg == "sha256") {
        md = EVP_sha256();
    } else if (sha_alg == "sha1") {
        md = EVP_sha1();
    } else {
        return -1;
    }

    int ret;

    EVP_MD_CTX *mdctx = EVP_MD_CTX_create();

    ret = EVP_DigestVerifyInit(mdctx, NULL, md, NULL, evp_verify_key);
    if (ret != 1) {
        ERR_print_errors_fp(stderr);
        return -1;
    }

    ret = EVP_DigestVerifyUpdate(mdctx, msg, msglen);
    if (ret != 1) {
        ERR_print_errors_fp(stderr);
        return -1;
    }

    ret = EVP_DigestVerifyFinal(mdctx, signature, signature_len);
    if (ret != 1) {
        ERR_print_errors_fp(stderr);
        return -1;
    }

    EVP_MD_CTX_destroy(mdctx);

    std::cout << "verify ok" << std::endl;

    return 0;
}