database size – What (kind of) DB can store store variable-length blobs without padding?

I have an offline task: store a HUGE amount of variable-length binary data on multiple hosts. Average data size is about 16Kb, total size: maybe hunderds of Tb. I have no consistency or speed requirement as it will likely have 1 client only.

When doing an interface mockup, I used SQlite and found this: when data pieces were all of the same length, the db file was only 4% larger than the raw data, but when I added variable-length data, the DB became almost 50% bigger. So it obviously uses some padding or reserving, and I don’t want to waste space like that.

Are there free databases that are known to be most efficient in terms of space for storing variable lengths of blobs? And provides an easy way to spread data across multiple hosts at same time?

tpm – What kind of “actions” can a TPM2 policy authorize?

I’ve been instructed to use the state of our system’s TPM’s PCR registers to prevent the system we’re working on from booting if one of the PCR registers is different from what we expect. In service of that goal, I’m reading over this article: https://threat.tevora.com/secure-boot-tpm-2/

there is a paragraph near the middle that reads:

TPM2 has the ability to create policies based off of PCRs: If the PCR contents do not match expectations, the policy will not authorize the action.

What kind of actions are they talking about here? And what would be the immediate ramifications if the action was not authorized?


Some background:
Before today, I was under the impression that the principle trick of the TPM was to encrypt or decrypt data using a key that the TPM holds securely. Now this article suggests that the TPM can also (two different functions) encrypt or decrypt data based on the current state of its’ PCR registers… this seems similar enough to my previous understanding that I can believe it.

If my understanding is correct, I can see how this would be useful to our project’s goals; encrypt a blob of data that is critical to the success of the boot (say… the kernel*) with the state of the PCR registers while the PCR registers are in a known-trustworthy state (i.e. while known-trustworthy software is loaded). If software that writes different PCR registers replaces the known-trustworthy software, then the kernel blob won’t decrypt properly, and execution “halts”. Presumably there are ways to handle this halting gracefully, like Bitlocker or LUKS; I imagine if I just encrypted executable code and then decrypted it with the wrong key, it would produce gibberish, and the machine would do unexpected things rather than halt gracefully when running that gibberish.

A co-worker has taken the position that there’s a simpler way; that a TPM can permit or refuse an action directly… so, like, it halts the processor or something, I guess? He doesn’t express himself very well, and when I tried to summarize his position he told me I got it wrong, so… I’m deliberately keeping the details of his position scant. Suffice it to say, my understanding of what a TPM does wouldn’t allow for what he describes…

You could interpret the two sentences from the article as supporting his position, or mine, depending on what actions it is possible to ask the TPM to authorize, and what the immediate consequences ramifications of the TPM denying you the authorization to do something. Does anyone here have an opinion?

*…how would I “encrypt the kernel”, exactly? :-p

What kind of service I need to point multiple domains to different webpages?

I would like to provide my users a way to publish their site, meaning I’ll be hosting it and I would provide them the DNS information so they can point their custom domain to it.

I’m totally new on this field so my question might seem a bit weird, so sorry about that in advance.

I’m currently using S3 and I created a bucket with many folders. Each folder being a user’s website published in “my hosting” (s3).
I would like each folder to be able to be accessed through a domain, but I was told that’s not common and in fact, probably not easy.

I’m open to new suggestions and I’m considering different ways but I’m a bit lost.

Do I need a “Reseller” hosting in order to do this?
I definitely do not want having to maintain / update / monitor my own server and I want it to be scalable, as I don’t know in advance how many websites I will have to be hosting and how much data transfer they will require.

In case this helps, all websites will be 100% static.

differential equations – How do you find the Inverse of Elliptic İntegral of Second Kind when modulus is large

So I tried to take the inverse of EllipticE when modulus is large, in Mathematica, but the solution gives wrong answer.

InverseSeries(Series(EllipticE(x, -k), {x, 0, 12}, {k, Infinity, 1}),y) = InverseFunction(y,k)

For example, I tried EllipticE(0.5,-9.9) = 0.656 where x:0.5 , k:-9.9, y:0.656

But InverseFunction(y,k) is not equal to 0.5. Am I not correctly taking the inverse of the function?
I need a general form of an equation for the inverse of EllipticE. Polynomial approximation is also fine. The approximation should definitely work around when x-->0 and k-->-infinity.
So for the above example, the approximation function result should yield to 0.5 when y=0.656 and k=-9.9. I need to code this function in MCU, so I need an analytical approximation.

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dnd 5e – What kind of terrain is allowed for Mirage Arcane?

The spell mirage arcane is problematic in that much is left undefined, or unclear. It is a 7th level spell, so its powers are unexpectedly great. Nonetheless, there must be some limitations to the spell. I’m specifically interested in the type of terrain that the local one can be changed to.

Jeremy Crawford once unofficially tweeted that targets could drown in an imaginary lake, or fall off an imaginary cliff, so we can assume that spawning a lake in the middle of nowhere isn’t too far-fetched.

The mirage arcane spell gives you tremendous latitude in how you make the affected terrain look and feel. The altered terrain can even hurt someone. You could drown in the spell’s illusory lake, for example, or fall off an illusory cliff.

1. Can extraplanar terrain be used? Places like the Elemental Plane of Fire are inherently dangerous to humans. Could you use Mirage Arcane to summon typical terrain from that plane, like a sea of fire (for example)?

2. Do acid lakes, toxic bogs, and active volcano calderas count as terrain? I’m inclined to say that if one can drown in an illusory lake, then surely one can melt in an illusory acid lake. The toxic bog though, it’s more debatable if its terrain components are the deadly ones. And I’m not sure if a big lake of lava is terrain.

3. Does the allowed terrain depend on location? Perhaps summoning a lake of lava in the middle of a calm meadow is a bit extreme (then again, perhaps not for a 7th level spell). However, surely if one were to use this spell in a volcanic landscape, then it would be appropriate?

java – What kind of developer am I looking for? (VR, Streaming, Online Library)

I am new to this platform after I found it during my research. Hope this community can help me.

For a new venture I’m starting up, I’m looking for a cto in a co-founder role. The company is about music production, promotion and publishing through LBE VR events. Think VR soundcloud for compositions of music and visuals.
I’m looking for a CTO in co-founding role and wonder what kind of skills he/she should bring.

Thank you for taking the time, I really appreciate it!

Man in the middle – What kind of data can the VPN service provider monitor / intercept / change?

You asked a few questions:

What kind of data can a VPN server log or monitor?

Date, time, to which server you have connected (IP and port), size of the request, response size, how often you have connected.

Can the VPN service provider monitor or intercept the entire length of the transmitted data or can it do so for part of it?

It depends on whether. If the connection is encrypted (e.g. TLS, SSH), the provider can intercept the message but cannot know its content, since the encryption is intended to protect against this type of attack. If the connection is not encrypted (FTP, Telnet, HTTP, POP3 and others) you can monitor and intercept everything.

Not only can you monitor messages, you can also copy, modify, and play them back. Signed in to a simple FTP server? Your login information can be copied. The files you have transferred can be copied or modified.

Can you also change the data and retransmit it when you go through the VPN server?

The same as above.

How do I know that the provider is not doing this?

The general terms and conditions. Yes, this boring, legalized page that almost no one reads. They usually say (in cryptic language) what they are monitoring and what is not.

Will they monitor you? Probably. Like every single Facebook beacon, every Google Analytics script and everything you navigate. It's bad? No worse than everything around you. And that's a legal thing (unless they say they won't be monitoring).

Will they steal your credentials and data? Unlikely. Aside from being illegal in almost all jurisdictions, it would bury their business fairly quickly. They have other ways to make money, and stealing data from their customers isn't the best.

How can you be sure that you will not be monitored, but protected? Rent your own VPS and install your own VPN. It may seem complicated (and it's not easy), but with the right tutorial, you can install Linux and run Wireguard in one afternoon for less than $ 5 a month.