Schneier on Security

Clive Robinson • February 23, 2026 9:37 AM

@ Bruce,

With regards,

“This is where I plug my own Password Safe. It isn’t as full-featured as the others and it doesn’t use the cloud at all, but it’s actual encryption with no recovery features.”

1, Not full-featured = lower attack surface.
2, Not use-cloud = lower future risk from Quantum computing on backups.
3, No recovery-features = lower risk of attack via systemic risk.

As for “it’s actual encryption” there are always risks with encryption in the modes, protocols and standards that it’s used within. However much of that should not apply and that which does can usually be mitigated against.

@ ALL,

With regards password managers there is an issue that is not much talked about…

Some services store all user data in an encrypted form with the key derived from the user password.

Sensible selection of the password can mitigate the risk of it being cracked and the encryption key recovered by a hostile third party.

However… Backups of the encrypted user data on a cloud or similar server can usually be acquired by a hostile third party who keeps it untill either,

A, They get a copy of the password.
B, The potential for Quantum Computing arises.

But there is more to it, with passwords stored in a file even though encrypted the chances are a user has a mixture of password strengths and once one is found the others are easier to find (especially if the encryption is not properly implemented).

Thus any password strategy needs to take these issues into account.

Also all communications encryption these days should be via a hybrid of strong pre-quantum and strong post-quantum crypto.

All file encryption should use the strongest encryption with the largest bit size that is secure, because Quantum Computing effectively halves the number of bits of key size of conventional encryption.

One mitigation is not to use “passwords” but other forms of “root of trust, shared secret” where proof of knowledge systems can be used where the “shared secret” gets checked by “zero knowledge encryption” etc but never put out over the wire.

Such systems can be built into “Hardware Security Modules”(HSMs) that can be built using “smart cards” in devices small enough to slide into a wallet.

But apparently these are not considered worth designing, building, and putting on the market…

Clive Robinson • February 24, 2026 2:15 AM

@ M Haden,

“How do you handle or recommend people document passwords in a way that people can access things once you pass from this realm?”

This is the last step of choice in a long chain of choices.

You first have to decide many things like what you want to be seen and what you don’t.

Some one once joked,

“Who do you want to leave your Pron Stash to -v- your will, and autobiography?”

Often when you get down to it a simple envelope inside an envelope inside an ordinary safe covers the last will and testament and other legal / financial papers or can be left in the care of a lawyer with instructions.

Because these things actually rarely change, and they also need to be handled correctly when you do “leave this realm” otherwise all sorts of things can go wrong, there is an old saying,

“Life is not about death and taxes…”

With the rider of,

“But if you have things of value then people will want them, and argue and fight over them, the rest goes to the garbage heap.”

So the first step is getting a very clear picture of what you are going to do with your possessions to what end, why and when as well as the character of those who might decide to change your wishes[1].

Only having got that sorted do you then move on to how do you ensure the right people get the right things and nobody gets the wrong things.

Stuff “on line” should be minimal and “subject to copyright” which as the IP goes on after your demise for upto around 75years might if you are an author or similar be important[2].

Only when you have a clear picture in your mind of what you want to happen to Who and When, can you move forward to the next stages of planning it out and putting it into practice with “fail safes”.

But consider a notebook or laptop computer in your fire proof safe with encrypted hard drives as being “volatile storage” and a separate written instructions like the will etc as “non volatile” storage. And for goodness sake ensure you do “off site backups” for both.

Key storage can be done via “M of N Shares”[3] encryption of the “master key” to your wallet, so that no one but you can access the volatile storage alone as you know “the master secret”.

The “pachyderms in the room” are the Software industry and legislation/regulation.

They are forcing people to not develop software that lasts more than a year or two at the most as part of their “business plan” to move every one from “owning to renting” as well as taking a massive slice out of software developers up front. For instance you do not own your “mobile phone” any more “for your own safety”… That is where all computers are currently heading be it the hardware or software and Governments want “back doors in everything”. So coming up with a software programme to do “secret sharing” or any kind of encryption is a very real issue.

Also “Don’t use Flash Memory” for storage, it’s now getting to the point where even a year of not being powered up causes the data to fade out… As for much more reliable floppy drives, when did you actually get one of those on a new computer?

All of this and more you have to think about well ahead of putting a plan into action.

[1] Remember things can go wrong when setting up trusts etc. In the UK for instance they changed trust laws so that children would get to benefit at the wrong age (whilst still teenagers). For the simple purpose of “putting wealth into the economy”. As I know from experience getting your inheritance when young makes you do things you regret in later life for reasons that may be beyond your control when young.

Also those you might chose as “guardians” for your own children etc might unexpectedly die before you. Again another issue I’ve had to deal with.

[2] Sir Terry Pratchett added his wife as co-author of his books for the copyright reason and set up a trust/foundation to manage the future of “Discworld” and other of his IP. He also left elaborate “data destruction requirements” for the storage in his writing computer. All of this takes forward planning and making sure people know well in advance the what and why of it.

[3] You can read up on the details of M of N or “Shamir’s Secret Sharing”(SSS),

https://en.wikipedia.org/wiki/Shamir%27s_secret_sharing

But the method might make your brain hurt for a while… So to put it more simply it is generally known that some geometric shapes such as a circle have a hard limit on what information is needed to make them. For instance the radius and it’s start and end point of a circle can be found from the circumference but you need a minimum of three arbitrary points on the circle to define it. Thus you could hand out five point on the circle to different people, knowing that a minimum of three of them are needed to find the radius length and center of the circle. The same idea applies to objects in higher dimensions.

Clive Robinson • February 24, 2026 10:24 AM

@ Rontea, ALL,

With regards,

“Ah, the classic password paradox.”

Is not really a “paradox” the solution is “get rid of passwords”.

The problem then becomes,

“Replace passwords with what?”

Which is why after something like 75years of knowing they are “bad news” we are still stuck with passwords…

One big issue InfoSec people don’t want to talk about is why “multifactor” is such a bad idea as well.

Because of the three talked about,

1, Something you have (token).
2, Something you are (biometrics).
3, Something you know (memory).

They are all fairly useless due to being physically “compelled” by authorities.

The Police are allowed to use “what ever force required” to get you to use the first two, and any threats they like for the third including endless jail without trial (see contempt legislation/regulation).

Which is why quite a few years ago there were discussions on this blog about how to “provably not know but use a password equivalent”

Various things were discussed but they all kind of revolved around having people “out of jurisdiction” using “M of N” key sharing via a public key comms system with hidden time syncing.

I realised that whilst that would work for “business travelers abroad” it was not practical for individuals or loved ones or if you were picked up in your home country.

There is a solution to this which is to extend the third factor with geo and time constraints.

That is,

4, A place you know.
5, At a time you know.

The problem now is that due to the E2EE battle various people realised they were going to loose, so have decided the way to go is “client side scanning” in the OS.

That is anything you say or do get sent back to the “mother ship” of Apple, Google, or Microsoft where an NSL or equivalent is all that is required regardless of what you who thinks you own the device –but nolonger do– want…