Web PKI: 3 improvements

Written on 24 September 2017, 03:09pm

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Some insights about web security from the excellent ‘Bulletproof SSL and TLS‘ book from Ivan Ristic.

– the Internet was not designed with security in mind
– the first efforts to improve this were in 1995, when SSL3 was released (by Netscape). Then TLS followed up.
– TLS 1.2 – the most recent version – was released in August 2008 (its successor – TLS 1.3 – is still under development, as of September 2017)
– the goal back in 1995 was to enable e-commerce. Today we have that (‘commercial security’), but we want much more.

One of the biggest problem with the Web PKI is the approach to certificate validation. The following improvements aim to fix that:
1. Public Key Pinning:
– addresses the fact that any CA can issue a certificate for any domain name without the owner’s permission.
– with pinning, site owners can select (pin) one or more CAs that they trust, creating their own (small) trust ecosystem
– delivered via HTTP headers (Public-Key-Pins)

2. HTTP Strict Transport Security (HSTS)
– allows web servers to declare that web browsers should only interact with it using secure HTTPS connections, and never via the insecure HTTP protocol.
– also, when an invalid certificate is encountered, it instructs compliant browsers to replace warnings with errors, disallowing bypass.
– delivered also via HTTP headers (Strict-Transport-Security)

3. OCSP stapling
– There are two standards for certificate revocation (revocation is used when the private key is compromised or no longer needed)
– CRL (Certificate Revocation List) is a large list of revoked certificate serial numbers maintained by the CA. Because of the size, the lookup is slow
– OCSP (Online Certificate Status Protocol) allows browsers to obtain the revocation status of a single certificate.
– the problem with OCSP is that the individual lookup can slow down browsing and can affect the performance of the OCSP responder for high traffic websites
– to address this, OCSP stapling allows each server to embed an OCSP response directly into the TLS initial handshake

In the end, do not forget that the current Web PKI is controlled by 2 actors: Certificate Authorities (interested in profit) and browser vendors (interested in market share).

Neither group has strong security as its top priority, but they are not necessarily to blame—at least not entirely. They won’t give us security until we, the end users, start to demand it from them.

Update 10 October 2017: I have just enabled HSTS here. Inspired by Troy Hunt.

Make the questions easy to answer

Written on 7 March 2017, 11:30pm

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About a month ago I was asking MalwareBytes to stop making me think.
I recently read for the 3rd time Don’t make me think (but actually the first time the paperback version 🙂 ) and I found a reference to another excellent book: Forms that work: Designing Web Forms for Usability.
I am at Chapter 3 – Making questions easy to answer – and there is the exact same situation as the one I encountered last month. The heading is ‘Turn negative questions into positive ones’, and I take the liberty to post the relevant paragraph here:

Happy to see this kind of confirmation 🙂

PS – Go buy the book! 30 EUR well spent. And it also comes with a companion site: formsthatwork.com


Written on 30 December 2016, 10:38pm

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These are some notes that I took while skim-reading The Guide to Wireframing.

What are wireframes?
Wireframes connect the conceptual structure to the visual design of a website/app.
They communicate 3 main points:
– Content
– Structure / Information Hierarchy
– Behavior / Functionality

How to do wireframes?
– paper drawing (sketching)
– whiteboard drawing
– paper kits (cutouts)
– digital drawing (Wacom devices)
– word processing software (Word, Google Docs, etc)
– presentation software: PowerPoint, Keynote
– graphic design tools: Adobe Illustrator, Adobe Photoshop, Sketch
– dedicated wireframing and prototyping tools: Balsamiq, proto.io, Axure, UXPin, InVision

Advantages of the dedicated wireframing tools
– element libraries
– flowcharting and user flows
– interaction with the wireframe: some wireframing tools offer the possibility to interact with the wireframes in order to showcase the behaviour (click-thgrough experience)
– collaboration (comments, feedback)
– presentation (pdf/ppt or standalone presentation mode)

Final point to remember
Delivering wireframes is not a goal in itself. The goal of wireframing is to deliver the final product, not the wirefames. So don’t aim for the perfect wireframe: as long as your wireframe delivers the intended message, move on.