"Computer Science" question

[listennui]

Part 2: more specific edition
(Added numbers to various parts in case anyone wants to specifically talk about one of the parts)
(Unspoiler only once done thinking about the initial post)

1. For a given configuration of bits as a real world physical property of this theoretical disk,^[1] does the presence or absence of an external key somewhere in the universe, regardless of where or how, determine whether or not that exact object would contain information or not?

2a. If, hypothetically, I somehow knew that a decryption key did exist for certain (by magic), but was invariably unattainable by any means by magic), would the disk contain information?

2b_lillian. In the previous scenario, does the key “exist” or does the unattainability necessarily contradict the ‘knowing it exist by magic’ part?

3. If the key was later discovered to exist, regardless of attainability, did the disk contain information before that discovery, or did the information only exist once the existence of a key was known? Or some third thing?

4. In a scenario where a key did not exist at all, but once we knew we needed to look for one and had some way of magically making the exact key to decrypt it (100% correctly by magic), did the information on the disk already exist, or was it made to exist by the key coming into existence, despite there being no interaction or changes with or to the disk? ^[2]

5. I couldn’t pic one, just look at the gifs in this set, it made me so happy

Sorry if parts of this are redundant with the op, just got too tired to double check
Btw the restrictions on physics nerds is lifted now

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1. really emphasizing that the disk is physical and has measurable properties ↩︎

2. I’m really showing my hand here ↩︎

[ashe]

Hmmmm . . . these are mostly thoughts about question 1 but here we go

This is where I start to wish we knew more about information theory and entropy because it honestly starts to depend (at least in our opinion) more on the contents of the disk than anything else. If the configuration of bits on the disk is something statistically indistinguishable from noise, then for 1 we think it doesn’t contain any information. The presence or absence of a key that would (in conjunction with the data on the disk) yield information is more to do with the properties of the key at that point, as the disk is in a high-entropy state, and would need a low-entropy key to make any significant information out of it.

But on the other hand if the contents of the disk were still largely unreadable, but had a recognizable structure - perhaps a partition table with a valid LUKS header . . . that very strongly implies that there is intent here, with information stored within. (It also conveniently narrows down the possibility space of “valid keys” to a much smaller set of values, rather than “literally any other set of data”)

Like I said all of those are thoughts mostly related to question 1 posed above, 2 a/b, 3, and 4 feel like they are venturing into “we need to define common terms like ‘what even is information anyways’” territory

Because like, we can take a brand new, unformatted disk, which will through random variations during manufacturing have some set of bits on it . . . and in the absence of any other structure we can invent a “decoding” scheme to produce whatever result we want, and so we’re kind of leaning into these vague ideas of structure and intent to determine whether meaningful information has been written to the disk vs just the random fluctuations already present there

(~ Dawn)

[Corruptor55]

Despite my answers being similar to those for the initial questions, I wanted to comment more on why they are here. I’ll go in numerical order, just like last time.

1. The existence or absence of a key (i.e., means of accessing a set of information) doesn’t affect whether a disk contains information at all. It only affects if the information can be accessed, and – if so – how and to what degree it can be utilized. A set of information being accessible is very different from it existing in the first place. It’s important to properly distinguish these concepts, in order to tackle challenges directly related to said information.

2. My explanations for these two parts are as follows:

(a) A known decryption key that’s inaccessible – again – doesn’t affect any information on the disk. It just means the information is unable to be accessed, but still exists regardless.

(b) Like I said earlier, the key is still known to exist, at least on a theoretical level. Many things in the world can exist (e.g., a fancy watch) while at the same time being unobtainable for various reasons (e.g., too expensive, limited stock, excluded to particular types of clients). So, a known, existing key that’s unobtainable (for whatever reason) is also a realistic possibility.

3. I/you/we (in this hypothetical scenario) already know the key exists, so why would it need to be rediscovered? Also, yes, the disk still contained information before that discovery even happened. Maybe not the exact same information organized in an identical way, but – yet again – still existing regardless.

4. As I’ve alluded to earlier…yes, the information on the disk already exists, no matter how the key to accessing it changes. I hate to sound harsh, but these questions feel like asking the same thing multiple times, in various ways, expecting the answer to change. They’re still valuable questions to ask, but – as I’ve concluded earlier – changing the conditions of the key doesn’t necessarily change the condition of the disk it affects. Or in other words, the key’s and disk’s conditions don’t affect each other.

5. Now, it’s time to tackle the totally most important question in this thread…
   Why do these science gifs make @listennui so happy?
   Though I can’t know the answer for certain (unlike in the previous questions), I think it’s because all of these gifs are so positive and so similar to each other, that they just connect together and spark happy chemicals in the brain ^-^ And yes, answering this last “question” I made up was my excuse to be silly for the day X)

Anyways, I hope you enjoyed reading through my nerdy ramblings again ^ <^ / /

[Drill]

@Corruptor55

Now, it’s time to tackle the totally most important question in this thread…
Why do these science gifs make @listennui so happy?
Though I can’t know the answer for certain (unlike in the previous questions), I think it’s because all of these gifs are so positive and so similar to each other, that they just connect together and spark happy chemicals in the brain ^-^ And yes, answering this last “question” I made up was my excuse to be silly for the day X)

I suspect the gifs are actually the contents of the disc that have been encrypted.

Also, cute nerd woman is cute.

[a_lilian]

Every time something beeps in the hospital.

[MajsterTynek]

If there was a hypothetical hard drive
that was encrypted [...] with an unknown key ([...]),
is information stored on the drive?

• Assuming said encryption took place.
• Assuming output got saved on the mentioned disk surface.
• With the question "is information stored on the drive?".

I can answer as the following:
The disk contains a very long number
obtained from a computational process,
which is inherently meaningless alone.

Direct answer:
The stored information is a number that potentially could be
decrypted when the used key gets discovered by any means.

Or, in theory, if data stored in a drive
was physically impossible to read,
is there data being stored at all,
or is being able to read it [is] a prerequisite
for it to be information/data at all

Everything that exists in the universe is information by itself.

Even if the driver of the HDD needle reports it as unreadable,
some shape of a magnetic field is still present there.

The mentioned magnetic field is an information,
which you are not able to retrieve and observe.

This topic alone is of a philosophical matter.

If there is no one to make data out of it,
should it be considered data at all?

Q.E.D.

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I have read whole thread and made a collection of:

Quote contributions I found meaningful

@Drill

Define information.

@ArcLyn

A perfectly encrypted disk with no known
decryption key is functionally identical to gibberish.

@sissel

[...], I also agree that information doesn’t necessarily
have to be readable to be defined as “information”, [...].

@a_lilian

I think the concept of “decryption” is really interesting
because I’m not totally sure that there’s such a thing
as a “correct” decryption?

Like in an epistemological sense,
is decryption recovering the original information,
or is it creating new information?

@a_lilian

The world is a cypher text and I can “decrypt” any number of different meanings from it, but is there a “true” meaning I’m trying to find or do I just want to grab whichever one will help me [...]?

@ArcLyn

Does “information” require intentionality or just usefulness?
Does it require either of those at all?

@Corruptor55

Not having the means to obtain something in the moment
doesn’t automatically make it invalid, let alone nonexistent.

@Corruptor55

In other words, data is a particular set of information
that exists independently of our own judgement.

@sissel

[...], random letters:
“asdl;kfj mfj asdjlnfkjas asdfkj”.
Say I put that sentence on that hard drive,
and assigned it the meaning [...].

To you,
the sentence is gibberish,
to me, it holds meaning.
Does it hold information?
I think so.

@sissel

A less extreme example is slang or dialects,
where certain sentences or words can hold meaning
to members of a culture but be gibberish to outsiders.

@Drill

[...]: meaning made from a misunderstanding
is still meaning and I think still valid!

@Wistellia

No matter how good the encryption is,
for it to be encryption and not just random noise,
there needs to be a way for the data to be turned
from the unencrypted state to the encrypted state.
Given this information, there must be a way to undo the process.

@ashe

if you throw the key away
that’s functionally equivalent to
writing random data to disk
and the input data being involved
is entirely unnecessary to the process

@listennui

[...] chance of getting a seemingly valid message
that [is] completely different than the [encrypted] info,
[...], it could be impossible to tell
what the actual original data was [...]

[Ymity]

I would consider information the usefulness of said data. To me it might have a low value, and to someone that has theh key it might have a higher value.

Not recovering data

In my case there are two possibilities:

• it's predictable with low entropy, (folows a basic pattern)
• it's unpredictable with atleast a minimum amount of entropy. ^[1]

So either it's empty (or effectively empty).
Or it is random enough for algorithms that rely on true randomness.

If this is a physical disk with subject to error it might generate enough entropy for useful applications.

Considering recovering data.

@a_lilian

Like in an epistemological sense, is decryption recovering the original information, or is it creating new information?

I think it depends on the encryption & decryption, lossless vs lossy compression.

• Lossless would recreate original data.
• Lossy creates different data ("new")
  But in the end the data is worth proportionally to the usefulness of the user.
  A lossy compressed image of a stranger vs my dog.
  It's not original but i definitely value it, regardless additionally i see the picture of my dog as more important to me.

Appreciate @achinti for showing me the thread.

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1. minimum defined in: Explicit Two-Source Extractors and Resilient Functions - David Zuckerman, where as above this limit we can treat it as true random (after a transform) ↩︎

[Choclad]

Hello! Whatever algorithm is used to list "New & Unread Topics" led me here. Apologies for reviving a dead thread, but I find this question to be fascinating and would like to chatter about it for a bit. I've skimmed the other answers but I wanted to quickly write out my thoughts just in case I rattle my skull and something new falls out. Thus, forgive me if I produce outcomes that have already been explored here.

TL;DR:

In all cases there is information on the drive. In terms of extracting information that is meaningful, useful, or true-to-original:

1. If we can get the full contents of the drive, run through the algorithm using our key, every time we attempt a key, it is impossible to knowingly acquire the original information without consulting whoever wrote it, but we can use the drive as a random number generator/library of Babyl to find or make our own meaning.
2. If there are a finite number of possible passwords to the drive and it will only return information if we get the right one, then attempting to brute force it will eventually give you the contents of the drive, or else the drive will corrupt on its own and there will be no meaningful information on it anymore.
3. If there is no possible password then the information is irretrievable and therefore irrelevant. The only meaning we can find in it is a discussion like this one.

Initial exploration

Is there information stored on the drive?

Yes. There is (presumably) binary data stored in electrical signals on the drive - since we interpret this as information, there is indeed information on the drive in the most trivial sense that a single active bit on the drive would be "information on the drive" (technically even all zeros would be information if the drive is otherwise functional)

A more interesting question is whether or not meaning is stored on the drive, which may be just me rewording your question in a way that suits my lexical preference.

For this purpose, I'd like to explore some avenues of approaching the question and see what cuts we can make.

Okay, but we can decrypt the drive

a theoretically unbreakable encryption with an unknown key

From the standpoint of a computer scientist, this is not really possible; unbreakable encryptions are a sort of myth derived from oversimplification. There exists a finite string of bits which encode for the encryption key, or a set of continuous physical circumstances which would be digitized into such a key; presuming that the drive is not in some sense aphysical, there would be some means of brute-forcing the key and you would, after some unknown number of eons, unlock it by simply trying all combinations of bits. In this sense the question is again trivialized by self-admitted pedantry; There is recoverable, meaningful information on the disk that is accessible by either humanly impractical or unlikely means. Either you will guess the key, or the drive will die while you attempt to. Indeed, if you can copy the string of bits held on the drive and its hardware, you can keep guessing forever.

This may be tangential to the original question, but I'd like to explore what it means to decrypt the drive if it has a finite, brute-force-able key and it returns its contents run through the decryption algorithm with the key each time we make an attempt at a new key.

Can we really decrypt it?

Then there is the question of a new sort of halting problem; when do you resolve your search? If you are brute-forcing this key, you will get back thousands, millions, trillions of permutations of bits; presumably, some infinitesimal percentage of those will decode into something that is only human or computer language, and of those, some infinitesimal percent will contain an apparently valid and meaningful combination of such. Which one do you select?

Even if you had an incredible amount of parallel compute power which could generate every possible key and determine if the resulting decryption generates a meaningful-looking result, you now have an impossible task - which of these apparently-meaningful decryptions is the one intended by the original writer(s) of the drive? If those writers are not present to confirm or deny, then your chances of selecting the "correct" decrypt is one, divided by the result of the total number of meaningful-looking decrypts minus those that you can in some way determine are not the correct one by context, presuming you know anything at all about who wrote the drive or why it was written.

Of course, if the drive never responds until we get the exact key, then our encryption problem is solved. Just keep guessing until data comes out. The drive that always returns something that might be garbage is actually more secure in this case than the one that is password-protected since in the latter case, the decryptor knows when they have reached the correct answer.

A communitarian answer

This brings us to a sort of philosophical conundrum - what is meaning? We have established that, by infinitesimal chance, we could technically select the writer-intended, original contents of the drive. In any practical sense, this leads us to one answer - writing was invented to store and share information, and what is on the disk is a form of writing. When a written item is unclear, and you want the original meaning, you go and ask whoever wrote it, or see if they wrote an explanation. Presuming that they are not present to provide me with a checksum, there is no way of recovering the meaning of the data on the drive except by pure dumb luck twice over. Even with all possible meaningful contents of the drive, your possibility of guessing the right one is probably very close to zero, and at that point you will not know you have derived the correct information.

A more romantic, albeit individualistic, answer

Is it necessary, though, to presume that the purpose of writing is solely to store and transmit information? Put a different way, if I choose a separate purpose for interpreting this data then I can come to a different answer; I don't need or want to know what the original writers intended, I just want to extract meaning from the data for some value of meaning that I find to be acceptable.

Let's say I simply love to follow the writings of infinite monkeys and find it exciting when they produce strings of words. Maybe there are strings of words on the drive! This excites me and I am spiritually uplifted by reading them. Meaning has been achieved. Maybe any of the meaningful-looking drives is enough for me. We have them! Meaning: achieved.

Let's say I am an augur of binary code. I have an algorithm that peeks at a truly random place on the drive and reads off the code and I interpret this by some system of cryptological tarot to ponder reality or maybe make assertions about it. By this system, maybe my explorations lead me to some genuinely enlightening intuition. By this method, any information can be digested into meaning; meaning is everywhere that there is information if you don't care about accuracy to the origin of that information.

Exploring the more aphysical outcome

Let's put my cryptography pedantry aside and assume there is no key or password that we are capable of producing that could access the data. We can rework this question into an equivalent philosophical thought experiment if we like:

There exists a box in which something has been placed, but the box has been locked by processes that make it physically impossible to open. Is there anything in the box?

The answer is, as before, trivially "yes" - we observed that something was put into the box before it was closed and for some reason we know that it will remain stored there. (i.e. we know that something is on the drive and has not been modified since the key was lost.) Our problem is that what was put into the box no longer matters. It's the quantum information paradox w.r. to black holes all over again: Yes, there is something inside of black holes, but we cannot know what form it takes and are causally separate from it. The drive in your question is the informational equivalent of a black hole. If something fell in, and it was the only copy of that thing that will exist, then that class of thing cannot be materially relevant to the universe ever again. (Except, in the physical case of a black hole, that now it has slightly modified the gravitational properties and momentum of the black hole.)

[FishEmoji]

@Choclad

Apologies for reviving a dead thread

IMO we should do thread necromancy often

[Choclad]

@FishEmoji

IMO we should do thread necromancy often