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Encrypted But Searchable Online Storage?

timothy posted more than 5 years ago | from the give-some-to-that-lawyer dept.

Data Storage 266

An anonymous reader asks "Is there a solution for online storage of encrypted data providing encrypted search and similar functions over the encrypted data? Is there an API/software/solution or even some online storage company providing this? I don't like Google understanding all my unencrypted data, but I like that Google can search them when they are unencrypted. So I would like to have both: the online storage provider does not understand my data, but he can still help me with searching in them, and doing other useful stuff. I mean: I send to the remote server encrypted data and later an encrypted query (the server cannot decipher them), and the server sends me back a chunk of my encrypted data stored there — the result of my encrypted query. Or I ask for the directory structure of my encrypted data (somehow stored in my data too — like in a tar archive), and the server sends it back, without knowing that this encrypted chunk is the directory structure. I googled for this and found some papers, however no software and no online service providing this yet." Can anyone point to an available implementation?

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fristy (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#27602649)

served ice cold

Am I missing something? (0)

thtrgremlin (1158085) | more than 5 years ago | (#27602681)

I thought that was what ssl was for.

Re:Am I missing something? (4, Insightful)

qbzzt (11136) | more than 5 years ago | (#27602729)

You're missing something. SSL is for data that is in transit. The poster wants the data to be encrypted on the server. That's easy - any encryption program can do it. But then s/he also wants to search it. That is harder.

Re:Am I missing something? (4, Insightful)

3p1ph4ny (835701) | more than 5 years ago | (#27602793)

No, this is not what SSL is for at all. SSL you have a party you wish to communicate with, but an insecure channel.

Here, you don't want to communicate anything useful to anyone. This is more a privacy preserving data mining problem. It goes something like this:

I have a long list of secret numbers 1...n. I do something to these numbers, so that Google doesn't know what they are, and then I send them to Google. Next, I want to know how many numbers are larger than, say k. So, I ask Google, but in a clever way, so that Google doesn't know what I'm asking.

Google then tells me how many of my original numbers were larger than k. However, Google doesn't know my original numbers, and they don't know what question I asked. There needs to be some theoretical mapping that preserves this privacy, but still allows the data mining to occur.

Re:Am I missing something? (2, Interesting)

thtrgremlin (1158085) | more than 5 years ago | (#27603733)

What it sounded like was that he wanted to keep a database with Google that was encrypted and wanted to search it remotely and securely, but without Google being able to look at the data. Even if that were possible, why are you trusting Google with that in the first place? Why not store it somewhere else? I would think keep encrypted data on a server and make a secure connection to it. You send your normal query across the encrypted channel to the secure server, it does its regular search and sends the result back across the secured channel. Add to that some secure authentication, and I thought that would have met the objective (even if the implementation is slightly different than described). If you wanted encrypted data stored in an untrusted location (why are you doing this again?) then you would think it would be necessary to hash specific queries as keys to encrypted data lacking the necessary information to decrypt the information remotely. Either way, guess I will see what other people are saying if this question seems more obvious (differently) to someone else.

Re:Am I missing something? (2, Insightful)

deroby (568773) | more than 5 years ago | (#27602841)

Yes you are =)

SSL only encrypts the transport.

It seems that the poster wants to have his data _stored_ in an encrypted way that is only decipherable by him, not by any of the machines/users at the storage facility. Yet, when he wants to do some search, he somehow expects the server to be able to do so... AFAIK that's not feasible.

(you could store whatever encrypted stuff remotely, but querying will require fetching, reading and decrypting the (relevant portions of) data locally...)

huh? (0)

Anonymous Coward | more than 5 years ago | (#27602709)

if the server cannot decipher the query it cannot execute it on a binary blob of encrypted data. FAIL.

Re:huh? (5, Funny)

HTH NE1 (675604) | more than 5 years ago | (#27602921)

if the server cannot decipher the query it cannot execute it on a binary blob of encrypted data. FAIL.

Gung jbhyq qrcraq ba ubj gevivny lbhe rapelcgvba zrgubq vf.

Re:huh? (4, Informative)

needs2bfree (1256494) | more than 5 years ago | (#27603115)

For the n00bs, the above post is in ROT13. Here is a link for a converter. []

Re:huh? (1)

grassy_knoll (412409) | more than 5 years ago | (#27603651)

Could also just use VI with the g?? command...

ohg gura gung zvtug or gbb zhpu jbex sbe fbzr.

Re:huh? (0)

Anonymous Coward | more than 5 years ago | (#27603265)

[rot13]That would depend on how trivial your encryption method is.[/rot13]

Not quite. It would depend on how trivial your definition of encryption is.

ROT26 (2, Funny)

davidwr (791652) | more than 5 years ago | (#27603293)

I prefer ROT26. It's got built-in steganography to boot.

Re:huh? (4, Insightful)

oldspewey (1303305) | more than 5 years ago | (#27602955)

Well that depends whether the OP wants to perform something like a fulltext search (i.e. the ability to look for keywords within the content of each document) or a metadata search.

There's nothing to prevent you setting up a CMS where each piece of content is encrypted, but the metadata describing that content is out in the clear and searchable. Security in such a scenario would be less than optimal (e.g. people could guess certain things about your content based on the statistical pattern of length for each of the millions of encrypted content items), and of course you'd have to be very careful about the metadata fields and how you are populating them.

Re:huh? (1)

Hognoxious (631665) | more than 5 years ago | (#27603313)

There's nothing to prevent you setting up a CMS where each piece of content is encrypted, but the metadata describing that content is out in the clear and searchable.

I'd assume that's exactly not what the OP means, on the grounds that it's so trivially obvious that nobody would need to ask it.

It's not possible even in theory (4, Informative)

nahdude812 (88157) | more than 5 years ago | (#27602719)

It's not possible to do this even in theory, unless you're relying on very weak encryption. The point of encryption is that you can't infer anything about the contents. If Google was able to infer enough to give you meaningful search results (if for example each word was encrypted by itself, and you searched for the encrypted version of the word), they would therefore necessarily be able to know enough to perform a frequency analysis attack on your data and compromise it in no time flat unless it was a very small amount of data (thus meaning search isn't really of value anyway).

You'll find a similar problem plagues any attempt at searching. Searching requires a certain knowledge or meta knowledge of the material being searched; and that knowledge necessarily dramatically weakens your encryption.

Re:It's not possible even in theory (5, Interesting)

TheRaven64 (641858) | more than 5 years ago | (#27602773)

It is possible. When you upload the data, you also upload an index. When you connect again, you download the index (which is much smaller than the data) and search that on the local machine. Neither the index, nor the data, is ever unencrypted on the server.

As for frequency analysis, I don't think any encryption algorithms published in the last 40 years have been vulnerable to this sort of attack...

Re:It's not possible even in theory (1)

jgtg32a (1173373) | more than 5 years ago | (#27602853)

That's because all encryption produced in the last 40 years has been based off of Division not Addition

Re:It's not possible even in theory (5, Informative)

TheRaven64 (641858) | more than 5 years ago | (#27602861)

Replying to myself: the scheme in the linked paper is not feasible. It performs O(n) searches, but this means that the amount of data you need to upload for the query is equal to the total amount stored. Since most consumer Internet links are asymmetric, it would be cheaper and easier to simply download the entire data search locally. The paper proposes having a server-side cache. This means that, for a typical block cypher, you would have a cache of every search term encrypted for each block. The server could then compare this to each block, but would not know what the plaintext is. This is not useful in any real-world scenario. The cache would be orders of magnitude bigger than the stored data and the search would sill be O(n), which is painfully slow. As I suggested above, uploading an encrypted index with the data makes more sense. Look at Apache Lucene or Apple's SearchKit for how to do this.

Re:It's not possible even in theory (2, Insightful)

flaming error (1041742) | more than 5 years ago | (#27603369)

> the amount of data you need to upload for the query is equal to the total amount stored
That's not how I read it. But the approach still sounds useless:

If Alice wants to search for the word W, she can tell Bob (the server) the word W and the ki corresponding to each location I in which W may occur

What's the use of encrypting the data if you're going to send keywords in cleartext to a party you're trying to hide the data from?

Re:It's not possible even in theory (3, Interesting)

FredFredrickson (1177871) | more than 5 years ago | (#27602865)

Mozy does this for personal/business backups. You can use a completely private key, but search your own data.

Re:It's not possible even in theory (3, Informative)

cakeninja (1534211) | more than 5 years ago | (#27603323)

Mozy does not encrypt your file names. Someone without your private key could still view your file names if they had your Mozy login information.

That's because they don't encrypt the filenames. (2, Insightful)

alanfairless (1420869) | more than 5 years ago | (#27603371)

And they can't search inside your documents.

Re:It's not possible even in theory (5, Funny)

felipekk (1007591) | more than 5 years ago | (#27603443)

Gee guys, isn't this a little bit too much work just to hide your porn?

Just mark the directory as hidden, your mom will not find it.

Re:It's not possible even in theory (1)

MobyDisk (75490) | more than 5 years ago | (#27603643)

So does Spare Backup [] . Just like Mozy, they don't encrypt the file names though. So you can search the file names, but not the contents.

Re:It's not possible even in theory (2, Informative)

BitZtream (692029) | more than 5 years ago | (#27603817)

And that would practically defeat the purpose of the encryption.

For the index to be useful it has to provide too much information about the encrypted data. The point of encryption is to ensure that nothing can be inferred about the contents of the encrypted data. If you give them a nice big bunch of information about whats encrypted, why bother encrypting it in the first place?

Given enough information in the index they could actually derive your encryption key as well with some simply brute forcing.

Maybe, maybe not (1)

MrEricSir (398214) | more than 5 years ago | (#27602779)

Unless you do the indexing client-side, and upload an index that's somehow encrypted...

I'm not saying I know how to do this, but it seems possible.

Re:Maybe, maybe not (0)

Anonymous Coward | more than 5 years ago | (#27602885)

Couldn't you also use meta-data? Attach a description of the file as meta-data and encrypt the file contents. That way you can search the meta data for key words, but your actual data remains safe. I suppose someone determined enough could use your meta-data as a crib and crack your encryption, but that's the risk you take.

Re:Maybe, maybe not (0)

Anonymous Coward | more than 5 years ago | (#27603127)

Cribs are useless on properly done modern encryption.

Re:Maybe, maybe not (3, Interesting)

The Moof (859402) | more than 5 years ago | (#27603035)

Maybe something like this -

Create an index of hashes using the unencrypted data on the client.
Encrypt the data on the client so we now have an index of hashes that apply to an encrypted file.
Upload the hash index and the encrypted data file to the server.
To search, hash the search criteria on the client.
Server search the indexes for the hash value, returning a list of encrypted files with an index matching the criteria hash.

Re:Maybe, maybe not (1)

MrEricSir (398214) | more than 5 years ago | (#27603395)

Sounds good to me. You wouldn't be able to get a "ransom note" but I guess that's an acceptable limitation.

Re:It's not possible even in theory (1)

blueg3 (192743) | more than 5 years ago | (#27602801)

Not possible in theory? You should tell the authors of the linked paper that describe how to do it in theory.

Re:It's not possible even in theory (1)

TheRaven64 (641858) | more than 5 years ago | (#27602929)

The algorithm in the linked paper requires you to upload at least as much data as is stored remotely for every search query. This is technically possible, but it would be cheaper and easier to download and decrypt all of the data locally then run all of your searches, which seems to defeat the point. The only occasion when their algorithm makes sense is when you are repeatedly searching for the same terms, but if you're doing that then you should just save your search results.

Re:It's not possible even in theory (1)

Homburg (213427) | more than 5 years ago | (#27603253)

That's true for their Scheme I, but I don't think it's true for Scheme II, or any of the subsequent schemes, is it? Scheme II and all subsequent schemes make the key for any word a function of that word, so, to search for a word, you just need to upload the word and its related key. I don't see why that would be anything like as much data as is stored remotely.

Now, the idea of making the key used to encrypt a given word a function of that word kind of sounds insecure to me, but I don't have the cryptography chops to back that feeling up.

Re:It's not possible even in theory (1)

TheRaven64 (641858) | more than 5 years ago | (#27603479)

Their subsequent schemes appear to rely on using asymmetric encryption (e.g. RSA) where you can provide the server with the public key and have it be able to encrypt, but not decrypt, data. Asymmetric encryption is massively more computationally expensive than symmetric, which is why it is never used for this kind of application.

Re:It's not possible even in theory (1)

nine-times (778537) | more than 5 years ago | (#27602807)

Yeah, I'm not sure I understand how meaningful searches can be done without decryption-- but then I don't pretend to be any kind of a genius about these things. It seems much more likely to me that there could be some kind of a system where unencrypted search indexes are kept locally while the files are encrypted and sent to an online storage service. Then you could search locally for the file you're looking for, fetch the encrypted information from the online storage, and then decrypt it locally.

That sort of thing seems entirely possible to me, but I'm not aware of any service that specifically offers that. I bet someone here could whip something up in 10 minutes to do it.

Re:It's not possible even in theory (3, Insightful)

smallfries (601545) | more than 5 years ago | (#27602973)

I'm curious - why would you post a comment claiming that this can't even be done in theory, when the submitter included links in the summary to a paper that shows that it can?

Re:It's not possible even in theory (2, Informative)

Anonymous Coward | more than 5 years ago | (#27603679)

"why would you post a comment claiming that this can't even be done in theory, when the submitter included links in the summary to a paper that shows that it can?"

          Because it can't. The one paper proposes (unless I'm missing something!) giving the server the word to search for AND the keys! The security is by frequently rotating the key, and if you KNOW you only wanted to search, say, chapter 1 of a longer document, only give the key for chapter 1. Not very secure!

          If the encrypted data has ANY types of patterns that can be used to infer the contents, the encryption system is weak. The only way to do this is to generate some kind of metadata (search indexes basically) locally, BEFORE you send up the encrypted files, send the metadata up *unecrypted*, and hope the metadata doesn't have sensitive data.

Re:It's not possible even in theory (0)

Anonymous Coward | more than 5 years ago | (#27602995)

Whether it is possible really depends on what type of operations you are going to allow. For example, it is possible to perform basic arithmetic on encrypted integers, without ever needing to decrypt them.

It may also be possible to achieve some form of security/searchability trade-off, in which the data which may be leaked is strictly limited while still providing the necessary usability.

Regardless of which ends up being the case, it certainly is not nearly as black and white as you imply.

Re:It's not possible even in theory (1)

hesaigo999ca (786966) | more than 5 years ago | (#27603089)

You could assign tags to the meta headers of the encrypted file, that can be grouped into sub categories, hence some file that says I am encrypted but I can vouch that I am an image, could prove useful

Re:It's not possible even in theory (0)

Anonymous Coward | more than 5 years ago | (#27603305)

Exactly. This is a stupid proposal.
I'm sorry to flame, but even considering this as a subject indicates to me that slashdot has gone downhill.
Meanwhile there are some real scientific curiosities that need to get discussed. WTC7, Nanothermate, and Jane Stanley come to mind.

It is possible to a certain extent (2, Interesting)

goombah99 (560566) | more than 5 years ago | (#27603307)

There are encryption algorithms that allow addition. That is, the sum of two encrypted messages is an encryption of the sum. I've forgotten how these work exactly, I think they are some many to one mapping, and the addition operation is not simply adding the encrytped numerical representations.

I came across these when looking at voting systems that allow N distributed people to vote in a way that sums the result before it is decrypted rather than decrypting to do the sum.

Anyhow what this means is that is possible to do certain operations on a remote database, like sum a column, without the database knowing the result and without transmistting anything additional information inbound or outbound.

You could presumably have your data stored in many forms on the database, each form suited for one type of query. Then you just query the approriate form to perform the operation of interest.

I'm reasonably sure there is no way to perform very high order operations that one might typically do in a relational database however.

Re:It's not possible even in theory (1)

guywcole (984149) | more than 5 years ago | (#27603811)

I disagree. Consider the case of journaling a file structure. It is possible to encrypt the data AND the journal. Then you need only retrieve, decrypt, and analyze the journal.

This retrieval can be done client side. The trick would be creating the journal. The only practical ways I see to do it are:
1. Have the server do it, which requires them (temporarily) seeing the decrypted data.
2. Do it before uploading, which requires having the entire data set client-side, which defeats the online storage.
3. Do it client side, which requires passing all the data over the connection but entirely storing it. Consumes network resources, but doesn't violate privacy or require substantial client-side storage.

Re:It's not possible even in theory (3, Insightful)

goodmanj (234846) | more than 5 years ago | (#27603877)

Can I have an anti-theft system for my car, so that nobody can steal it but anybody who wants to can take it for an anonymous test-drive?

You want to... (4, Insightful)

mhkohne (3854) | more than 5 years ago | (#27602725)

Use an encrypted query to match against the encrypted text. The problem is, if the text is REALLY encrypted, then there shouldn't be enough information to do this - the encrypting of the original text should make it impossible to even match against it.

If it didn't, then an attacker who got hold of the encrypted text and some of your encrypted queries might well be able to mount an attack based on commonalities between the two.

Encryption is NOT difficult... (0, Troll)

Smidge207 (1278042) | more than 5 years ago | (#27602937)

Rob Malda (aka Cmdtaco) is not what many would consider "the ideal candidate" for a dot-com start-up. He started his career as a C++ coder for a major manufacturer, but then quit to pursue a mathematics degree in Canada. That didn't quite do it for him either, as he then dropped out to pursue something far more interesting: canoe from Calgary to New Orleans. But after 1,200+ miles of rowing, his journey ended in Minneapolis with a cracked butt and a frozen river. Temporarily, of course, as he plans to pick up and continue south someday soon.

All that said, Malda was pretty excited when he received his first response to all the resumes he'd been sending out to various tech companies. He immediately called back to schedule an interview and was pleasantly surprised at how flexible the interviewer was: Malda could "stop by any time."

After shaving his pubic area smooth and putting on his interview clothes (leather pants, leather boots and leather vest, steel nipple rings and nothing else), Malda hopped on a bus, transferred to a few other busses, and, after almost two hours, finally reached his destination. It was a residential apartment complex that had obviously seen better days.

When he knocked on the door of "Suite 318," Malda was greeted by Michael Simms, a spry-looking man in his 50's with glasses precariously perched on his conical head and a face a few days past shaved. Upon entering the squalid apartment, the first thing Malda noticed was the rotten stench of ejaculate-stained underwear haphazardly strewn across the living room. There and a blue tarp hung over the south-facing window, blocking the sun and a view of the Mississippi river. "For my little get-togethers" Michael Simms explained using quote marks with his fingers. "Can't have the neighbors looking in now can we?" The second was Michael Simms sitting down on a computer, firing up a popular MMO. He was completey nude. Malda stared unabashedly at the sight; Michael's tumescence was incredible.

"You see this," Simms said, avatar running towards the closed city gate, "when you get to the door you have to wait while the game loads the next area. You should just be able to see out through it."

Taking this as the "technical" portion of the interview, Malda started to explain about how he would implement dynamically loading regions. Malda was very clear that, while he had never written something like that before, he was certainly aware of the basic concepts involved.

"Now, look. He just runs right through the tree. Right through it! You see that?" He harrumphed and turned toward Malda with a look like someone died. "Motherfucker! I'll fucking kill you!" Rob shouted.

"Now now, Rob, that will never do. You'll suck my penis to erection and then take it in your sweet little anus until it's time to dump a load of Uncle my special sauce down your slick throat, and you'll like it!"

With this Simms cocked the hammer of his gun and pointed it at Rob's mouth and began forcing his jaw open with the barrel as he poured the JÃfgermeister, thick and dark and brown, into Rob's mouth. He trickled some onto his bush and penis for good measure and jammed his thin cock into Rob's mouth. Rob took it to the hilt.

"That's a good little faggot. You take all of Uncle Eric's junk and you like it!" Eric said as he began pumping his cock in and out of Rob's mouth. Simms's bulbous white gut hovered menacingly over Rob's face like a full moon and his ruddy pubes tickled Rob's nose. The gun barrel wavered at Rob's eyes.

Rob moaned as Simms grunted his pleasures into the back of Rob's throat.

"Now Rob, I want you to look me in the eyes. Rob's beady eyes connected with Michael's pale blue irises, tears welling in his eyelids as Simms's crotch continued its assault. "I have with me a funnel, Rob, and you're going to take it in your ass. This old cock of mine needs a little lube and we're going to pack your rec-room full of something quite slippery!" Simms said as his eyes grew wide. He shook his bottle of JÃfgermeister again as he helped Rob pull his pants off.

With a pop Michael removed his pulsating cock, slick with spit, from Rob's hungry mouth as Rob turned over onto all fours, his back arched and ass swaying in the air. Simms's little orange funnel entered Rob's anus without complaint as he began pouring the brown fluid. Rob shivered.

"Good boy, Rob. Good boy." Simms moaned as he rammed his dong home into Rob's familiar rectum. "Reeeal goooood..."

Rob cried out in pain as Simms put his full weight into each and every thrust, Rob's hairy ass-cheeks spread further and further apart with every push.

"OK, Rob, I want you to say hello to my little friend!" Simms said with a maniacal laugh. Rob hissed as he felt something cold and metal begin to enter his asshole right beside Simms's rigid cock. "What's the barrel of my .44 feel like up there, Rob?"

"I can't take this anymore! I was done with this when I moved from Ann Arbor! I just want to have a normal straight life with Kathleen, I justÃ"" Rob said through sobs and grunts as he continued his battering ram assault. "I just want to live a straight lifestyle and leave my gay days behind!" He grunted one last time, withdrew his gun and cock from Rob's bloodied anus, and shoved Rob onto his back.

"Get ready to take my load, boy!" he yelled as he jacked his crooked cock into Rob's mouth. He kept his .44 focused on Rob's forehead as he began pouring the brown liquor into Rob's mouth. A few drops of the spirit hit Simms's dick and he lost control. His butt cheeks tightened and his hips thrust forward and backward like a piston as his scrotum tightened.

"You little fucking Linux faggot, take my load!" Simms shouted at the top of his lungs. Spurt after spurt of sickly yellow hacker semen erupted from Simms's straining purple cockhead into Rob's gullet, the JÃfger splashing Rob's face and mixing with the cum into an infernal homosexual cocktail. Rob gagged and flailed his arms.

Rob laid gasping and spitting after Simms climbed off of his spent form. Rob turned and looked at Simms as if in a trance. Blood and semen and JÃfgermeister leaked from his sullied lips and collected in his goatee. Sweat and more JÃfgermeister covered his brow. His eyes, bloodshot from the alcohol, strained to make out Simms's pudgy form shuffling in the darkness. Rob started but then cried out in pain as his ass spasmed. His hand went to his sore, puffy anus and he rolled around in his soiled sheets. His eyes were glazed over, almost catatonically. He began crying again, his whole body wracked in weeping.

Simms pulled up a website with a few 3D models on it and asked, "what does 100,000 polygons mean? Hey, could we just have the program write whatever text we wanted over these signs so we could sell ads in-game?"

Malda felt at a disadvantage since he hadn't done any 3D programming since toying around with POV-Ray work a decade ago. He struggled through an explanation about how models are essentially a web of triangles with a flat texture projected onto them, and that in-game ads should not, in fact, be difficult.

"Really? Golly." Simms said. "Okay, they tell me we can finish this in six months if we work part-time, so we can probably finish it in three if we work full-time."

He had been describing a game as complex as Spore.

"I'm outsourcing most of the work to the Philippines. They're willing to work on a royalty basis. You can transmit the technical requirements to them, change my words into code they can understand."

"Change... your words... into code... they'll understand..." Malda gibbered.

"Really, you can do that?" Michael Simms peered through his glasses.

At that point, Malda had given up all hope that a decent game could be made. But he still wanted to know how much money he could get out of this guy...this queer chicken-hawk. "So... how much would I be getting for this?"

"$75,000 per month," Michael Simms said, with no hesitation.

Malda blinked. "That's, um, after the game's done, right?"

Michael Simms pulled up a spreadsheet. "A popular game gets about 250,000 players. At $15 a month, that means they pull in... $3,750,000. They tell me to pay about 10% of that to the developers. I'd give you 2%. That's... $75,000." He smiled at the screen.

"But, ah, nothing until we're pulling in that kind of money?"

"We'll offer advertising in the game," he said. "For gay sex. Don't you think companies like Google would like to get in on this, advertise in our game?"

He blinked again. "I'm not sure Google really needs that kind of exposure." Deciding to go on the offensive, Malda said "Okay, a friend of mine, Calvin, worked for five years on his game, Venture the Void. Go ahead and pull it up at"

He started typing in the address bar: "venture of the void". Malda corrected him and soon colorful planets and spaceships swirled on the monitor. It was a gay site to behold.

"Okay, see he's generating all these planets automatically. No two are the same, they've got times of day, automatically generated weather, plants... You see that spaceship? No two of them in the game are identical, even over multiple plays. All that and guess how many paying players he got?" Malda paused. "Twenty-five."

"Oh," Michael Simms said, "but did he advertise on this site?" He navigated to the third or fourth hit on Google for "MMO". It was some portal for MMO games with reviews, news, and all sorts of things.

"I'm not sure," Malda hesitated, "Calvin submitted it lots of places."

He just shook his head. "All that work and he didn't even advertise in the right places. If he just would have advertised here, he could have been rolling in the money."

It was pretty clear that Malda wasn't going to get any money out of this engagement, so he decided to cut his losses and make the long journey back to his own apartment. As he stood up to end the interview, Michael Simms casually blurted out "I never leave the apartment."

Malda raised an eyebrow.

"I've got an idea every day," he said. "I'll just be doing something then, POW! An idea! That's why you need me. Now, look at this."

Michael Simms walked over to his closet and took out one of those massive wargames from the 70's. He told him about a "compare and contrast" essay he had in college, "comparing tic-tac-toe to checkers to chess to games like this with thousands of pieces." Ten years ago, he presented investors the idea of developing a series of games like this on the computer. "ÃIt's just like printing money!' they told me."

Not one game chit had been popped from its original cardboard. Malda couldn't help but wonder if any investors had sprung for this free money.

"Have you ever played the computer game Civilization?" Michael Simms asked. Before Malda could even nod affirmatively, he continued "One time I was playing and a chariot parked in the mountains defeated a howitzer! That's just never going to happen. One time I just sat down and started writing down things that were wrong with the game. POW! I had a list of ninety things, just like that."

It was time for him to go. Malda wished Michael Simms luck, but told him frankly what he thought of his enterprise...that it was shit. After his two-hour ride home, the first thing he did when was email his friend Calvin the link to the magical money-making MMO forum, asking for only 2% of his proceeds. He expects to be rolling in money any time now.


Re:You want to... (3, Funny)

noidentity (188756) | more than 5 years ago | (#27603777)

The problem is, if the text is REALLY encrypted, then there shouldn't be enough information to do this - the encrypting of the original text should make it impossible to even match against it.

NOT TRUE! I use a combination of XOR and rot-13 encryption and I'm able to do text searches just fine. The trick is to encrypt the search string, then it'll work perfectly. This is because the encryption doesn't depend on the position within the text, but that shouldn't hurt security too much.

Easy (1)

AchiIIe (974900) | more than 5 years ago | (#27602777)

This sounds pretty easy,
a) obtain database, indexing tools, search tool
b) install on the machine and encrypt the entire hard drive with any of the many available whole-disk encryption tools
c) ssh in and run queries.

Re:Easy (1, Insightful)

Anonymous Coward | more than 5 years ago | (#27602965)

RTFQ read the question again, please. With disk encryption the data would still be unencrypted in the server's RAM. The OP wants something much more sophisticated... data always encrypted in the server (HDD, RAM, CPU) but with the ability to search it. Not that easy to me.

Good luck with that.... (1)

Statecraftsman (718862) | more than 5 years ago | (#27602783)

Just to clarify the OP's idea. They want to store only encrypted data on the server, send only encrypted queries to the server(that the server can't even decrypt), yet they expect that the server will be able to send them back results. I don't think it can happen but surprise me.

The best I think you can do is store and transfer the data in encrypted form and put the indexes and any search logic on the client. Maybe the index could be stored on the server as well and synced to the client, but creating the index will require access to the plaintext.

Re:Good luck with that.... (0)

Anonymous Coward | more than 5 years ago | (#27602925)

It *IS* doable, but not the way you think ... and it only works for exact searches, not less than, greater than, etc...

  1. Encrypt the data locally
  2. then send the encrypted data to the server for storage.
  3. Encrypt the search term you're looking for (example: "John Smith") with the same encryption algorythm
  4. Search the db for records with the result of the previous step.
  5. decrypt your results.

-- tomhudson (not logged in :-(

Re:Good luck with that.... (1)

billcopc (196330) | more than 5 years ago | (#27603233)

That only works for very trivial encryption algorithms, where you can map the unencrypted string character-by-character to its enciphered value.

The reason for this is you don't know where the text resides within the document, so if your cipher is not position-independent, you're screwed. Hint: anything more robust than XOR or ROT13 will be position-dependent.

Example for the truly dense: Let's say you have two strings. One is "Harry" and the other is "Barry". They only differ by one character, so if your cipher results in encrypted data that still differs by a single character, it becomes quite obvious that the two strings are very similar. To an attacker, this says your data is very easy to decipher, as it is effectively a 1-to-1 code list. You can perform a frequency attack or a few other stastical techniques to very easily find a decryption table, and in the case of binary data, you can look for telltale patterns like JPEG headers or other predictable, repetitive structures.

Re:Good luck with that.... (1)

deroby (568773) | more than 5 years ago | (#27603327)

That won't help either...

Assuming you encrypt this piece of text : "three wrongs don't make a right, but three lefts do !"
You'll get some binary blob A

Encrypting the word "three" will give you another binary blob B

The chances that you'll find B inside A is practically zero due to the way modern encryption works.

(It would work in the mighty ROT13 system though !)

Re:Good luck with that.... (1)

KDR_11k (778916) | more than 5 years ago | (#27603377)

That only works if you have a block cypher with no chaining or other alteration of the blocks (which means an attacker could e.g. modify your data by copy-pasting blocks) and a search query that fits neatly into full blocks and only has to match when the data also contains the query spread out exactly like that (if you specifically store your data like that by e.g. padding with whitespaces after every word an attacker can perform a frequency analysis on the queryable words). That's extremely weak. An important part of good cryptography is that you can't see when a part of the plaintext is repeated which conflicts entirely with the requirement that the server can recognize the cyphertext of your query.

Short answer: No (0)

Anonymous Coward | more than 5 years ago | (#27602787)

Long answer: Nope

Re:Short answer: No (0)

Anonymous Coward | more than 5 years ago | (#27603467)


Re:Short answer: No (1)

psergiu (67614) | more than 5 years ago | (#27603849)

Please tag story as: no

It depends on the encryption (3, Insightful)

davidwr (791652) | more than 5 years ago | (#27602827)

If the data is encrypted in independent "chunks" from which search terms can be built then this is trivial: You pre-encrypt your search terms and search for them. Searching a word ROT13 [] -encoded document works this way, as each character is encrypted individually and an encrypted search term is made up of encrypted characters.

Once you get past this, it's no longer easy. You basically have to either make the term you are searching for look like all possible values of the encrypted text and return all matches, or decrypt the document somewhere.

If the encryption is good and any particular chunk, extract, or other slicing-and-dicing of the encrypted data without the key looks random, you are pretty much stuck with decrypting it somewhere.

The alternative is to store an index, or at least a list of keywords, in clear text. For example, a document describing how to build a nuclear bomb could have a list of 10 or 20 non-classified keywords attached to it to aid searching. But that's not what you are asking for.

Slight correction (1)

davidwr (791652) | more than 5 years ago | (#27602903)

As pointed out by others, the index can be stored encrypted, then downloaded locally. However, this means the index is what is being searched, and it - the item being searched - is in fact not being searched on the server. In practice this has value, but it's not what this thread asks.

Roll your own solution (1)

Anonymous Showered (1443719) | more than 5 years ago | (#27602835)

If you don't trust your data in others' hands, don't give it to them in the first place.

The (costly) solution:
1) Get a 1U server from ACME with appropriate hardware
2) Install favourite Unix-based OS, e.g. FreeBSD
3) Configure server with appropriate software, e.g. Truecrypt, SSH, etc.
4) Find open source search engine software to index your data, see (or look for recommendations on /. ... a future Ask Slashdot, anyone?)
5) Place server in a secure co-location facility
6) ???
7) Profit.

Re:Roll your own solution (1)

HTH NE1 (675604) | more than 5 years ago | (#27603211)

Isn't that just another way of giving the co-location facility the method to decrypt your data and search terms? They have physical access to your hardware, even if you do encase it in Gloopstik®.

Re:Roll your own solution (1)

JBdH (613927) | more than 5 years ago | (#27603813)

If you store all harddisk data on your co-located server encrypted and use the Intrusion Detection feature present on most servers to instantly erase any unencrypted data from memory, you're pretty safe I guess.

searching encrypted data (1)

Bert690 (540293) | more than 5 years ago | (#27602855)

There are techniques to do this but none have made it out of academia. Most are quite inefficient and support very restricted querying models. Here's one paper that claims their methods are "practical" (but always keep in mind that academic claims of practicality should always be taken with a grain of salt): []

Re:searching encrypted data (1)

Bert690 (540293) | more than 5 years ago | (#27602913) []

Doh! Just noticed you already are aware of that particular work. Anyway, congrats, you're already aware of the state of the art!

Hand over the keys (0)

Anonymous Coward | more than 5 years ago | (#27602897)

If you want the server to do a meaningful search, you have to hand over the encryption keys. Otherwise how is the server knowing what it should look for? It is the same situation as having a safe in a bank with a secret code, and then asking the bank to look in the safe for you. You have to provide them with the code, otherwise they can't open it. Since you mention at the same time you don't trust the server (bank), and want it to peek in your data (safe), how can you simultaneously ask them to do exactly that?

Easy solution (1)

junglebeast (1497399) | more than 5 years ago | (#27602909)

" I send to the remote server encrypted data and later an encrypted query (the server cannot decipher them), and the server sends me back a chunk of my encrypted data stored there â" the result of my encrypted query. " There are only 2 ways in the universe for accomplishing this, but they are both simple: Method 1: Send entire database to user for any search query. The results are bound to be in there somewhere! Method 2: If the server is powerful enough, brute force crack the encryption scheme, find the results, then re-encrypt it and send back to user. Anything else would violate the definition of full encryption. Of course, you could have "partial" encryption with unencrypted meta-data that the search is performed on.

GNUnet (1)

diablovision (83618) | more than 5 years ago | (#27602911)

It's been done. GNUnet [] .

Anon. networks are something else (1)

davidwr (791652) | more than 5 years ago | (#27603081)

What this thread is about is "I have a file that is secret. I want to encrypt it into an opaque, un-encryptable-without-the-key blob. I want to upload it to a search engine. I want to do searches against it."

The answer is "By definition, it can't be done, not in the way you want. If it's transparent enough to search, it's no longer encrypted enough to be called encrypted. Other solutions, such as using indexes, may provide some of the practical benefits you want, but they are not without risk."

A guy walks into a bar... (5, Insightful)

skathe (1504519) | more than 5 years ago | (#27602915)

...and when the bartender asks him what he would like to drink, the guy says "I want what I always get, but I don't want you to actually pour the drink, just help me search behind the bar for the liquor I want, and the hand it to me without seeing what it actaully is, and charge me correctly without any knowledge of what it is you just helped me find."

Re:A guy walks into a bar... (2, Interesting)

richie2000 (159732) | more than 5 years ago | (#27603229)

But... That's not a valid car analogy since you're not allowed to drink and drive.

Re:A guy walks into a bar... (1)

Anonymous Coward | more than 5 years ago | (#27603701)

Fine, here's your car analogy:

An english braille reading deaf and blind taxi driver gets into his car at the airport and puts the in service light on. A foreign passenger gets in and says "daba dooba dooba da" and expects to arrive at his requested destination; regardless of the fact that the taxi driver is blind, deaf, and doesn't can't comprehend dabadoo.

Re:A guy walks into a bar... (1)

maxume (22995) | more than 5 years ago | (#27603779)

Sure you are. That you open yourself up to various legal consequences is quite different from not being allowed to do it.

Re:A guy walks into a bar... (3, Funny)

HTH NE1 (675604) | more than 5 years ago | (#27603363)

Not good enough. The bartender could audit his liquor to see how much of each bottle was dispensed.

This is why when they do this sort of thing, the gentleman just serves the bartender a National Security Letter and takes more than what he wants without paying a dime.

not impossible; not easy (2, Interesting)

Lord Ender (156273) | more than 5 years ago | (#27602919)

Keep the files on the remote server, encrypted. Keep the search index in a database, encrypted in chunks. Rsync your search database between your local machine and the server. Actual searches of the databases would be done locally.

Result: terrible performance whenever you access your data from a new machine (must sync entire search database). Good performance the rest of the time. Remote server never sees anything but cyphertext.

Seriously, how did this post get green lit? (0)

Anonymous Coward | more than 5 years ago | (#27602927)

Is there no moderation?

The "editors" are idiots. (0)

Anonymous Coward | more than 5 years ago | (#27603141)

I'm surprised this wasn't kdawson's doing.

Re:Seriously, how did this post get green lit? (0, Offtopic)

KDR_11k (778916) | more than 5 years ago | (#27603449)

You mean how did this post get filed under Ask Slashdot instead of Humor?

Now there's an oxymoron if there was one (1)

DaleGlass (1068434) | more than 5 years ago | (#27602947)

There's plenty meaning that can be derived from just filenames.

Does it really matter that Google or whoever can't see the exact text or images, but has enough information from filenames, tags and descriptions to accurately find out what kind of furry porn you like?

People who encrypt their data often don't want to disclose even what kind of content they have. Knowledge of what sort of porn is there, or that you're having an affair, or private internal company data are things that can be disclosed from just knowing document titles without having to even look at the exact file.

The solution to this is to take Google out of the equation. Encrypt your computer's hard disk, encrypt all your mail, build your own search database that will be stored on the encrypted disk, and search that.

I'm confused... (1)

Manip (656104) | more than 5 years ago | (#27602949)

So you either want to:
- Decrypted
- Search

If so, then just mount an encrypted drive and put the Search Index on the drive its self... Basically any encryption filter driver will do the mounting for you (Windows and Linux ship with these) and any old Search Software will work for the searching, just move the index.

Or you want to:
- Search Encrypted Content
- For other encrypted content (or decrypted content)

In either case this isn't possible. At least assuming you're using a Crypto algorithm written in the last thirty or so years then it won't work. Even in World War 2 they had encryption that would make this harder than just decrypted it.

I don't understand... (2, Funny)

dschuetz (10924) | more than 5 years ago | (#27603011)

...isn't this easy?

Plaintext: "Attack at dawn"
Ciphertext: "lkaoiuast98u;aw"
Search query: "oiua"
Result: "lkaoiuast98u;aw"

What could be simpler?

(no, I'm not an idiot, this is a joke.)

My way of tackling the problem... (1)

migarg (716984) | more than 5 years ago | (#27603067)

would be to first encrypt each document word-by-word (this can lead to really big documents because of paddings), then the client would transmit the document together with the encrypted words as plain text. In this way, the search engine indexes meaningless words which points to the encrypted documents (you can use two different algorithms and/or keys for word-by-word encryption and for documents). For searching your client encrypts the keywords (asking for the encryption key) and once you have a link you have to decrypt the document.

There should be some weak link in this chain, but I don't find any: be the first to claim my two cents.

Re:My way of tackling the problem... (0)

Anonymous Coward | more than 5 years ago | (#27603521)

Yep. Weak link is that identical plaintext will always produce the same cyphertext. Very bad for secure encryption.

One very common way to avoid that little problem is called Cypher Block Chaining. In a nutshell, each block of plain text is exclusive ored with the previous generated block of cyphertext. And after the XOR operation, it is then encrypted. This works perfectly for the 2nd to the last chunk of data. But for the 1st piece, there isn't a prior piece of cyphertext to XOR with. The solution is to create what's called an Initial Vector which acts as the 1st piece of cypher text. This initial Vector is usually randomly generated. Using a randomly generated initial vector and cypher block chaining, the exact same message may be encrypted with the exact same key and result in a HUGE number of different appearing cyphertexts. For a cypher with a block size of 8 bytes, there can be 2^64 different cyphertexts that all represent the exact same plaintext message. And none of the cyphertexts will look anything like each other except for their all being the same length.

And you want to index this cyphertext how? And obtain a meaningful search?

Nope. Not gonna happen.

querying encrypted data howto (2, Interesting)

burnin1965 (535071) | more than 5 years ago | (#27603085)

As long as your query looks something like this...

SELECT * FROM mydata WHERE stuff LIKE '%YToyOntzOjc6InBhY2thZ2UiO3M6MjM5OiKyKHPh9ZawDX6KyA62cMd6p+mjBybGwJyCaNfFb7S.........

Seriously though, if I understand your objective I think it would be feasible to develop something like that, but I don't think its something you could integrate into Google's search services unless they added something on their end.

You could pass a decryption key along with your query and the server would then decrypt records as it performed the search. It would be very resource intensive.

As an close example, I have a web based password storage application in which I did not want to keep the encryption keys on the same server as the password database. So I generate a key with which to encrypt the records and the user keeps their key and must supply it every time they want to decrypt a record. I don't go so far as to enable searching of the encrypted data, I have a description field specifically for that purpose. The web application is called Passbox [] and is written in PHP.

What an oxymoron! (2, Interesting)

hesaigo999ca (786966) | more than 5 years ago | (#27603113)

Yeah, Id like my cake and eat it too!

The only way this could work is if you has tags in the meta header of the encrypted file
telling you that yes I am encrypted, but I have an image in me or my encrypted data is of the type accounting.

This might work for indexing searches where you want to be able to return all the files on the pc (encrypted or not) that are images or etc...

The Hack you're looking for.... (0)

Anonymous Coward | more than 5 years ago | (#27603165)

With any strong encryption, the server's copy of the data will be unsearchable.

A solution provider like Google could:
Write an AJAX app. that index the data before you send it, and then send the data and its encrypted search terms to the server to store. This will let you encrypt your search terms (like a "very well distributed hash") and have the server return all the documents that match your keys. I have as yet to see this done well.

Or, you can https to a server you have placed in a colocate, hand the web page your credentials and have it mount an encrypted growable volume of your data that you can act on with Perl and flat indexes. A serious Linux Hacker could put this together for you as a couple weeks work. I've done this with one of my servers online, but ultimately it proved easier just to ssh to the box mount the encrypted volume with a single command and grep for the files of interest. Command line affection is not a disease.

Good luck.

Encrypted blob in cloud, unencrypted index locally (1)

koick (770435) | more than 5 years ago | (#27603217)

Just throwing out an idea for an implementation:

The uploaded blob to the cloud is encrypted. But there resides a local index for searching it.

I haven't had a need for this (as I inherently don't trust the cloud) but if someone knows of this type of implementation perhaps it's enough for the poster.

Re:Encrypted blob in cloud, unencrypted index loca (1)

dalhamir (1423303) | more than 5 years ago | (#27603401)

damn, beat me to it. only efficient way to do it. Basically, you'd be doing your own searching, and not relying on google's search algorithms.

Easy (1)

Smallpond (221300) | more than 5 years ago | (#27603239)

Randomly say that you found or did not find the search pattern. Since you're not decrypting it, nobody can tell if you're lying.

This seems obviously impossible but it isn't (1, Insightful)

Anonymous Coward | more than 5 years ago | (#27603255)

This seems obvious impossible, but it isn't. The problem, of course, is in how the server can perform a search when it isn't even able to decrypt the message telling it to do a search.

However, there is nothing inherently impossible in defining an encrypted datastructure and an algorithm where you can perform computations on the *encrypted* data, without having any idea about what it is you are computing. There is no reason that you need to decrypt data before you can do computations with it. It just needs to be the case that when you perform an operation on the encrypted data, some predictable other operation happens on the data inside the encryption. The result of this encrypted computation will then be something still encrypted, which can be sent to the client who can then decrypt it and find inside the result of his query.

So it isn't obviously impossible. In fact the theory of multiparty computation makes it clearly possible, though the overhead of doing it that way would probably be too high.

Ask the NSA. (1)

fahrbot-bot (874524) | more than 5 years ago | (#27603285)

I'm sure they copied and decrypted the data when you uploaded it.
(This is why I wrap all my data in tin foil.)

There is a way, kind of: PIR (2, Informative)

Naerbnic (123002) | more than 5 years ago | (#27603475)

There is a cryptography technique called Public Information Retrieval which allows you to do just that: Send an encrypted query to a server, let it perform some operations on your behalf, and send you an encrypted query result. The server neither knows the contents of the encrypted data, nor the content of the query, but you have your result nonetheless.

The intuition is that there exists a sort of "black-box" operation which some cryptographic techniques can use. For example, if I have two encrypted bits a and b (where I can't tell what a and b actually are), I can still perform the operation a xor b. The result is encrypted, and I don't know the actual operands or the result, but I know that what came out is indeed the encryption of the xor of the encrypted bits. Such cryptosystems are forms of "Homomorphic Encryption".

Using this, we can then give the server a search term thus encrypted and, using the black-box opertaion, have it do some set of operations which will reveal the result. The server will execute the exact same set of operations independent of the search term, so it knows nothing (and needs to know nothing) of the search term contents. Of course, this implies that the server has to operate on every element of the encrypted data to do its job, but that's the fundamental tradeoff. If you're willing to accept that, and the additional computational overhead, you can design such a system.

Have you tried PGP NetShare? (0)

Anonymous Coward | more than 5 years ago | (#27603495)

I played around with it and I believe with some more time and effort it could have worked. Wasn't that concerned about data security however.

Impossible? Not true (1)

ccleve (1172415) | more than 5 years ago | (#27603505)

It's very possible to do this.

The trick is that search engines deal with symbols, not necessarily words or characters. If you change the words and characters to different symbols then you're set. Imagine a dictionary of words that associated each word with a number. You keep the dictionary and don't give it to the vendor. You just give the numbers, and send your query in numbers. It works.

This particular scheme wouldn't be very secure, but it easy to imagine better ones.

Here's what you need: a search engine that allows you to modify documents as they go into the index, and also allows you to specify custom tokenizers, morphological analyzers, and whatnot.

The search engine I developed does this. []

Privacy enhanced databases (1)

peterwayner (266189) | more than 5 years ago | (#27603557)

This is a great challenge and an active area of research for some time. Many researchers would like to build databases that protect the users without creating some huge pile of aggregated personal information.

Encrypting the data at the client is a good solution. I've posted several good case studies from my book, Translucent Databases .

Here's what I wrote for a library [] and here's a case study of helping an online store. []

Let me know if you have questions or suggestions.

Windows Search 4.0 (1)

DigitalJer (1132981) | more than 5 years ago | (#27603579)

...has an option to index encrypted files.

create your own search index. (0)

Anonymous Coward | more than 5 years ago | (#27603601)

you need an search index on that server. Attach to that server via ssl, query it using encrypted text. that text will be decrypted and processed via the index on that server. Results are encrypted and sent back. You then unencrypt your results.

Unfortunately SharePoint provides the equivalent (0)

Anonymous Coward | more than 5 years ago | (#27603607)

SharePoint can prevent even server-admins form accessing the uploaded/stored data, while still allowing users/groups with authorization to the data to search it. I know this is a missing feature in Google's Mini/Appliance, and one of the reasons corporations have a problem with Googleâ(TM)s solution.
Some other search providers have similar authorization-based solutions, which indirectly fulfills your need. Be wize.

Anonymous Coward (0)

Anonymous Coward | more than 5 years ago | (#27603617)

Freenet uses a search feature that searches encrypted data.

You need a private VM or a hosted machine (1)

wiresquire (457486) | more than 5 years ago | (#27603785)

As pointed out above, if the data is encrypted, the service can't search on it.

- you get a VM or a hosted machine that you have complete control over.
- You set up all your encryption as necessary, eg encrypting the file system. SSL to the machine, etc
- You set up a search system, eg lucene, or maybe database as SQL queries are needed or whatever.
- Profit(?)

Of course, you could do all the same in-house as well, without the need for encryption etc.


I put something similiar to this together myself.. (3, Interesting)

airjrdn (681898) | more than 5 years ago | (#27603821)

But it may not be everything you're looking for. My requirements were:
1 - Mask the filename
2 - Encrypt the contents
3 - Add recovery data in case the file got damaged
4 - Ability to view unmasked filename from web

I put together a batch file I could drag/drop multiple files onto that used WinRAR to compress the files (individually), with encrypted filenames, a password (of course), and included archive recovery data. It then used ReNamer to encrypt the .rar filenames. After that, I simply FTP'd the files to the server.

I had a webpage that would accept a password, and unencrypt the filenames so they were viewable in readable form on the page. Each one was a hyperlink. There was an extra step required if you wanted the downloaded filename to be unencrypted as well.

After uploading 115G or so, my host alerted me to the fact that they didn't allow me to keep offsite backups there. :) So in the end, I'm not even using it at the moment.

My solution didn't allow me to search within the files, but it did allow me to store files on the server that they had no way of viewing the contents of, or guessing the contents of based on filename.

Not really feasible (1)

gweihir (88907) | more than 5 years ago | (#27603847)

There are some solutions for this. I think the first appraches were called "Iraiksan". However there is a massive performance penalty so you are unlikely to find this offered anywhere. Better keep metadata on your local machine and search that.

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