des_expand_key
err = des_expand_key(dctx, key, keylen);
int des_expand_key(struct des_ctx *ctx, const u8 *key, unsigned int keylen);
err = des_expand_key(&tmp, key, DES_KEY_SIZE);
EXPORT_SYMBOL_GPL(des_expand_key);
err = des_expand_key(des_key, prep->data, 8);
err = des_expand_key(&ctx, key, sizeof(key));