Articles Cards Topics About

Tag

security

8 cards

Cards

A multi-tenant query missing its tenant filter and returning every customer's rows, the four isolation levels from shared table to cluster per tenant, and row-level security enforcing the filter in the database

SecurityDay 52Sep 23, 2026

One Missing WHERE Clause

system-design security multi-tenancy

Envelope encryption splitting one key into many short-lived data keys wrapped by a master key inside a hardware module, with every unwrap logged and rotation touching the small keys rather than every row

SecurityDay 51Sep 22, 2026

The Key That Guards The Keys

system-design security encryption

A user fired at 10am whose JWT stays valid until 11, the three parts of a self-contained token, and short-lived access tokens paired with a server-side refresh token that can actually be invalidated

SecurityDay 50Sep 21, 2026

The Token We Can't Take Back

system-design security jwt

Handing an app a password against granting it a scoped token, the five steps by which the app never sees the credential, and what OpenID Connect adds on top of OAuth

SecurityDay 49Sep 20, 2026

Let Them In Without Giving Them the Keys

system-design security oauth

Authentication answering who you are against authorization answering what you may do, the one-digit URL change that reaches another person's record, and enforcing ownership at the data layer

SecurityDay 48Sep 19, 2026

Logged In Is Not the Same as Allowed

system-design security authorization

The same architecture diagram seen from the builder's view and the attacker's view, the six STRIDE prompts applied to every arrow, and trust boundaries as the place to ask

SecurityDay 47Sep 18, 2026

Draw the System, Then Draw the Attacker

system-design security threat-modelling

Password hashing compared — SHA-256 at a billion guesses a second against bcrypt and argon2, plus per-user salts that stop one cracked password revealing the next

SecurityDay 29Aug 29, 2026

The Algorithm That's Fast Is The Problem

system-design security password-hashing

Your Agent Is A Confused Deputy — system design card, day 17, ai systems

AI SystemsDay 17Aug 17, 2026

Your Agent Is A Confused Deputy

ai ai-systems security

Stay in the loop

New articles on technology, finance, culture, and life. No spam, unsubscribe anytime.

Narchol

A word that carries meaning, weight, and intent.

About Disclaimer RSS

© 2026 Narchol. All rights reserved.