Read X509 Certificate expiration date

certificate.cpp

char buf[32];

std::string ReadExpirationDate(X509* certificate)
{
	std::string timeString;
	BIO* bmem = BIO_new(BIO_s_mem());

	if (ASN1_TIME_print(bmem, X509_get_notAfter(certificate))) {
		BUF_MEM* bptr;

		BIO_get_mem_ptr(bmem, &bptr);
		timeString.assign(std::string(bptr->data, bptr->length));
	}
	else { // Log error
	}
	BIO_free_all(bmem);
	return timeString;
}