zauguin's comments

zauguin | 1 month ago | on: TPM on embedded systems: Pitfalls and caveats to watch out for

Can't that just be done by sealing to PCRs? By protecting the unsealing key with PCR which depends on the OS (I usually use the secure boot signing key PCRs since they are different between systems and stable across updates) and some PCR which gets extended by the OS (or for stuff stored in NV making it readlocked during boot). Then any process that launches later can no longer access it and booting another OS also doesn't help.

zauguin | 2 months ago | on: Some Epstein file redactions are being undone

This seems highly misleading.

> - Remove the data. This is much harder than it sounds. Many PDF tools won't let you change the content of a PDF, not because it isn't possible, but because you'll likely massively screw up the formatting, and the tools don't want to deal with that.

Compared to other formats this is actually relatively easy in a PDF since the way the text drawing operators work they don't influence the state for arbitrary other content. A lot of positioning in a PDF is absolute (or relative to an explicitly defined matrix which has hardcoded values). Usually this makes editing a PDF harder (since when changing text the related text does not adapt automatically), but when removing data it makes it much easier since you can mostly just delete it without affecting anything else. (There are exceptions for text immediately after the removed data, but that's limited and relatively easy to control.)

> - Replace the data. This what what all the "blackout" tools do, find "A" and replace with "🮋". This is effective and doesn't break formatting since it's a 1-to-1 replacement.

That's actually rather tricky in PDFs since they usually contain embedded subset fonts and these usually do not have "🮋" as part of the subset. Also doing this would break the layout since "🮋" has a different width than most letters in a typical font, so it would not lead to less formatting issues than the previous option. Unless the "🮋" is stretched for each letter to have the same dimensions, but then the stretched characters allow to recover the text.

> The problem with "replacing" is that not every PDF tool works the same way, and some, instead, just change the foreground and background color to black; it looks nearly the same, but the power of copy-and-paste still functions.

PDF does not have a concept of a background color. If it looks like a background color in PDF, you have a rectangle drawn in one color and something in the foreground color in front of it. What you usually see in badly redacted PDF files is exactly this, but in opposite color: Someone just draws a black box on top of the characters. You could argue that this is smarter since it would still work even if someone would chnage colors, but of course, PDF is a vector format. If you just add a rectangle, someone else can remove it again. (And also copy & paste doesn't care about your rectangle)

zauguin | 1 year ago | on: Volkswagen reintroducing physical controls for vital functions

I'm somewhat disturbed by the idea that anyone would think that you shouldn't stop when "driving in even semi-dense traffic in any bigger city" if you can't see. Of course you should slowly come to a halt and put warning slights on to give people time to react, but not coming to a stop in such a situation seems at the very least highly negligent. Sure, stopping in the middle of the road will be annoying to other drivers, but it's generally preferred to annoy people over killing them.

zauguin | 1 year ago | on: No more boot loader: Please use the kernel instead

This is a step in that direction. What they are proposing is not so much "no bootloader" but using a small Linux as bootloader. I'm using a similar setup for some time and it gives some of these advantages. Especially you get support for all relevant filesystems (you can support everything Linux supports because it is Linux), it can dynamically build a minimal initramfs with only the needed drivers if you want to and understands module dependencies (e.g. it can just dump the list of modules it uses itself) and is generally much more flexible.

zauguin | 2 years ago | on: Advice for new software devs who've read all those other advice essays

This often leads to extremely annoying codebase because languages trying to enforce styleguides without proper options just leads to inconsistency once any code in another language leads to the codebase.

Just have an options file which is checked in with the code and enforce whatever is set in there works much better. You still avoids all the useless discussions about formatting while also allowing to set sensible settings which are consistent with surrounding technology.

zauguin | 2 years ago | on: Show HN: Encrypt and upload files to IPFS from browser

According to NFTStorage's Terms and Conditions:

> The Service is offered for the creation and storage of NFTs. Use of the Service to store other types of data is not permitted.

Do you have a special agreement with NFTStorage which overrules the general Terms and Conditions?

zauguin | 2 years ago | on: Show HN: PDF Debugger – Inspect Structure of PDF Files

Regarding 2.: Most of these objects do not directly correspond to rendered elements. Basically every page has one (typically) content stream which will contain all rendered elements. The biggest rendered thing you see outside of that are annotations (link boxes, form fields, actual annotations, ...).

It's a bit different if you are looking at a tagged PDF, where the tagging structure is in there, but if you want to look at that in detail you are probably better served with e.g. ngPDF (https://ngpdf.com/) which will show the tagging structure including the mapping to rendered elements.

zauguin | 2 years ago | on: B612 Font Family

While there is a glyph like that there's no nice way to access it. There is no font feature to enable slashedzero by default and slashedzero is not mapped to U+0030 U+FE00 (Unicode's standard variant for an explicit slashed zero). Instead it's only accessible using the private use codepoint U+E007 and then typically doesn't get copied as a regular zero.

But more generally the font has an empty GSUB table which would be used for such substitutions. I'm wondering if the cockpit display maybe misses support for that and that's why they tried not to use it for anything.

zauguin | 2 years ago | on: American Satirist C.J. Hopkins Sentenced in German Speech Case

There's no need to appeal yet. With "punishment order" they probably refer to a german "Strafbefehl" which isn't a full sentence but a simplified system to avoid trials which only requires a bit more than probable cause.

They can now object to it, then there will be a full trial. If they loose there, then they can appeal.

zauguin | 2 years ago | on: Fixing the TPM: Hardware Security Modules Done Right

Potentially. Last I tried to boot Windows was a Windows 10 which could deal with this, it just disabled some functionalities relying in the TPM (aka. Windows Hello(?)). It might be that Windows 11 will not like it that much.

Then again, if you want to control what runs on your system, you probably don't run Windows in the first place.

Also if you want to stop Windows from booting, it's much more reliable to change the Secure Boot keys (and of course not adding the Microsoft keys afterwards). Then your system is guaranteed Windows free.

zauguin | 2 years ago | on: Fixing the TPM: Hardware Security Modules Done Right

On Linux with tpm2-tools installed you can run

To set the owner password (mainly for Storage) ``` tpm2_changeauth -c owner file:- ```

To set the endorsement password (e.g. to verify that the TPM is authentic): ``` tpm2_changeauth -c endorsement file:- ```

To set the lockout password (to recover the system without requiring a full reset): ``` tpm2_changeauth -c endorsement file:- ```

zauguin | 2 years ago | on: Fixing the TPM: Hardware Security Modules Done Right

> or, even better, to prevent the HSM from being used by anything without my overt permission

Can't you already do that with an existing TPM? You just set an owner authentication password and an endorsement authentication password and no application can use it anymore unless you provide the password.

Technically it would still be possible to use it as a very slow cryptographic coprocessor I guess, but that benign and useless. It does still provide access to some platform measurements, but they can't be signed by a authenticated (or even safely stored) key, so they are easy to fake.

In addition to that the OS of course can be used to completely block access to it if needed.

The problem is not that people can't stop applications from using it, it is just that in practice people don't care.

zauguin | 2 years ago | on: CNET is deleting old articles to try to improve its Google Search ranking

According to the Open Source Definition of the OSI it's not:

> The program must include source code [...] The source code must be the preferred form in which a programmer would modify the program. Deliberately obfuscated source code is not allowed. Intermediate forms such as the output of a preprocessor [...] are not allowed.

zauguin | 2 years ago | on: Meta blocking news links in Canada

If all media outlets no longer receive traffic from big tech companies there's actually a decent chance that it will not affect their traffic much. If only some news outlets would be affected the others would profit, but if all are than there is a good chance that people just start accessing news more directly again.

zauguin | 2 years ago | on: 32“ E Ink screen that displays daily newspapers on your wall (2021)

> OTOH if the display is already 2300EUR, I can't see how the OP can possibly make any money on this, especially with free global shipping, returns, etc, etc.

I don't think they are making money out of this. The display is 2300€ without VAT and the OP is selling them with 2783€ with 21% VAT, so it's exactly the same price.

zauguin | 2 years ago | on: 32“ E Ink screen that displays daily newspapers on your wall (2021)

Could you give a few more details on this? While the 32'' screen is a bit too expensive for me, I would probably find interesting usecases for he 16'' version if there weren't the subscription requirement. I don't mind writing my own CMS as long as that's possible.

What are the requirements to make a system work with these? Do you at the end stream bitmaps to the device? Something else? Is there a documented interface?

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