struct sdesc {
	struct shash_desc shash;
	char ctx[];
};

static struct sdescinit_sdesc(struct crypto_shash *alg)
{
	struct sdescsdesc;
	int size;

	size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
	sdesc = kmalloc(size, GFP_KERNEL);
	if (!sdesc)
		return ERR_PTR(-ENOMEM);
	sdesc->shash.tfm = alg;
	sdesc->shash.flags = 0x0;
	return sdesc;
}

static int calc_hash(struct crypto_shashalg,
		     const unsigned chardata, unsigned int datalen,
		     unsigned chardigest) {
	struct sdescsdesc;
	int ret;

	sdesc = init_sdesc(alg);
	if (IS_ERR(sdesc)) {
		pr_info("trusted_key: can't alloc %s\n", hash_alg);
		return PTR_ERR(sdesc);
	}

	ret = crypto_shash_digest(&sdesc->shash, data, datalen, digest);
	kfree(sdesc);
	return ret;
}