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Privacy With a 4096 Bit RSA Key — Offline, On Paper
HavanaF writes "Online backup is practical, but can it offer any privacy? The Dutch security company Safeberg developed an Offline Private Key Protocol, with an asymmetric key scheme. The protocol demands that the private (decryption) key be stored away from the 'source' computer, which presumably is 'too vulnerable.' The catch is that the private key needs to be fairly large to be secure: a 4,096-bit RSA key should suffice for some years. But how to store an 800-character key offline? Safeberg introduces a machine readable paper key, with the 4k-bit key crammed in a giant 2D Datamatrix barcode. This video on key strength tells the story."
... you fold the paper your 2D key is on? Tears, that's what. Tears.
Guy holding knife and laxatives: "Poop the paper! Poop it now!"
"Hegelians, who love a synthesis, will probably conclude that he wears a wig." - Bertrand Russell
Hang on! let me get my giant barcode out of my pocket!
I'll fax you a xerox of my public key. Is analog the new steam punk?
So what could be so hard about memorizing a measly 800 or so characters?
#DeleteChrome
This sounds like a way to put punch cards back in every office.
Looking for a job?
Want your resume written professionally?
DON'T USE TUNAREZ!!!
Than a 4096 Bit RSA Key that is stored on a standalone computer?
Online backup is practical
not for my 1.5 terabyte HDD which is about half full.
Right now backing up from hard drive to hard drive takes forever (hours). How the fuck am I gonna back up to a remote server over the internet at 60 kbytes/sec?
I am sure that such a gentleman would not be using the venacular "poop".
Science advances one funeral at a time- Max Planck
If the source computer is vulnerable, the private key will be vulnerable as well as soon as you use a device connected to the compromised computer to scan it.
After surfing around a bit on the source site I can't find any compelling reasons why I should use a giant unwieldy printable 2D Barcode instead of a smartcard ? A smartcard reader costs 25 bucks now a days so that cant be much of an obstacle.
Good point. "Poo" would save valuable syllabants!
But standalone computers are not a renewable resource the way paper is.
Image this scenario. Instead of generating a "key" the traditional way you have the user select a file of his or her choice, then an offset and length. So if the user has some jpeg on their machine called goodtimes.jpg that is 100k and they input the offset of 3456 bytes and length of 77654 bytes, the key is then generated using the data inside that file. All they need to remember is the filename, offset and length. The file could be stored on the machine in plain site, or on a removeable pen drive. or even on a public website somewhere using http to access it.
Datamatrix is the Gif of the barcode world. It has a bunch of patents covering it.
PDF417 does mostly the same thing, can be read with a laser (instead of an imager) and was designed to be open source and patent free from the beginning.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
It would be hell if you lost the symbology though. Otherwise, this is very practical to the few who understand what been done.
http://www.maxineudall.com/2010/02/should-economists-be-sued-for-malpractice.html
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Cryptography Feed @ Feed Distiller
you need that much security, for some reason I am 1000000% curious of what you are doing now. If you had an old 286 machine in the corner I would likely just ignore it
"Defecate thy papyrus!"
"Hegelians, who love a synthesis, will probably conclude that he wears a wig." - Bertrand Russell
Do people actually use the systems they produce and sell?
Free Manning, jail Obama.
Since the purpose of this is to backup critical data, you want to make darn sure that you never loose the key, or all the data is worthless. Storing pieces of paper securely and safe from disaster is something that we have been doing for years, and you don't have to look very far for a solution. On the otherhand, most safes, fire boxes and safety deposit boxes will still get hot enough enough in a fire to destroy any digital media stored in them.Paper offers a simple, traditional backup while something like a smart-card could be used on a day to day basis.
This is so obviously an advertisement for the Safeberg product... but also is so stupid of an idea that: ok, I'll bite.
Storing your key as a UPC graphic is NO MORE SECURE than printing out the hex characters in human readable format. Granted it takes more time to manually copy... But what? you think that your thief don't have a camera on hand to peruse your key later or just steal the paper? This is called security by obscurity... which doesn't count towards security in a meaningful way.
Then there is the paper vs other storage formats. How the heck does this company believe that putting digital keys on paper is any more secure then putting them onto a digital storage medium. If data is burned onto a CD or stored onto a USB key and removed from the computer... it is just as "offline" as any other non-digital object. So what's with the paper.
Are you looking to save money? Paper vs USB/CD? Not relivent unless you have thousands of keys and want to individually secure or release them on demand. So for the average user or business... there is no cost savings benefit.
Also, USB is physically strong. Depending on the housing, you can usually put it through the washing machine or run over it with a car. Do that with paper.
This is so ridiculous. Some guy must have thought this was a brilliant idea at one time. Too bad he wasted so much money on this idea by setting up a bogus website to appear as a valid company with good/usable ideas. Please avoid this product and their proprietary suggestions at all costs. I think their concept is actually a reduction in data security and integrity.
IMO, based on the video and what I read on their site... Safeberg is a very bad company with very bad ideas.
Real Solution: put your digital keys on USB. Store your USB in a safe private place. Call a bank and get a lock box.
Could it perhaps be printed on say, a cracker? That fellow that swallowed the USB flash drive to prevent investigators from using it for evidence might be interested.
Account -> Discussions -> Disable Sigs
I just spilled coffee on the bar code!
(Just a what-if scenerio.)
I'm not sure I grok this notion of not storing the key with the source machine. I mean... if I can get to the machine you backed up... I don't really need to get to the backup, do I? I've got fresher data right there in front of me.
Now, if you're really trying to protect some kind of historical record of how your data has progressed over time, then that would be a reason why access to the source computer still didn't get the intruder access to what you're trying to protect... but that's a very special case.
Dunno. Maybe I'm just missing the point.
Why not just use OpenPGPCard 2.0? It supports up to 3072bit RSA keys, and I'm sure bigger keys in the future.
Just unplug, and it's offline. Seems a lot more secure than a barcode on paper.
Hey, that's a great idea! But I guess if someone flips through the book, s/he'd be able to find it. Here's an additional idea: print various fake keys in addition, on other pages, and only you know which page contains the real key. Although I guess, unless you use a lot of fake keys, the enemy would be able to just try each key in turn. Defense to that: combine the key with a password, so they have to break the password for each key they try: simple with 1 key, but not so simple if they have multiple keys to try.
How do you print the key in a book, anyway?
404555974007725459910684486621289147856453481154 in hex is "You sank my Battleship?"
[GPG key in journal]
You could use long strips of paper with holes punched in it (or not punched). Or you could build one of these with a somewhat longer strip of paper.
[Insert pithy quote here]
Interesting? Seriously? Roflmaowaghm!
LOAD "SIG",8,1
LOADING...
READY.
RUN
It is extremely convenient to use google documents to store current work online. Access is available from anywhere. I believe a 4096 RSA key is totally unnecessary for protection because the password is for entry to the online vault, not to decrypt a downloadable document. Presumably an online vault would object to even a dictionary attack. Most online vaults (e.g. mail accounts) close up for a time after three failed attempts.
If the account is compromised, it is almost certainly because the owner was not careful about the security of their password. Or maybe the owner chose a password like their birthdate, or used the same password as for the website dodgyfellows.com
ECC-521 exceeds RSA4096 in terms of security strength, and it would only require approx 75 ascii chars to represent the key. It's still ridiculously long, but it's certainly much shorter than the 800 chars required by RSA4096!
If the companies that need this level of security are anything like the one I work for then they are in serious trouble. More likely yet instead of printing the file and tucking it away I will just save it as a pdf on the public web folder. We might spend big bucks developing the data but im sure our printer that they would use to generate the key would have a bad print head at just the right time for this key to be generated when we need to recover it. And can you imagine what the back door entry key for the NSA might look like when printed. I can imagine it being NSFW when you look at it from a distance.
http://www.jabberwocky.com/software/paperkey/
No affiliation, but throught it worth a mention. Also not affiliated with the following, which would've been a million times more useful as open source:
http://www.xerox.com/Static_HTML/xsis/dataglph.htm
This is presumably also (or somilar to) the technology behind photocopiers and such detecting images of money.
Or you might consider it no more secure than a 64-bit key, as the entire scheme is based solely on computational power and assumes that there will be no significant breakthrough in that area. Computing power is still based largely on the number of transitors we can put on a chip and the cycles per second (currently GHz range) we can operate them. Be for computional was electrical, it was mechanical. Before it was mechanical, it was manual.
Quantum computing offers a possibility far beyond standard electrical (transistor) based computing. Even if Quantum computing is never fully realized or does not live up to expecations, it is extremely pessimistic (bordering on irrational) to assume that we won't realize computing power capable of handling far more than 4096-bit keys. Yes yes. I know. The time -investment issue. Follow the curves over the last 100 years and this will still be trivial.
This makes absolutely no sense. Smart cards have been around for many years now. There, you NEVER give ANYONE or anything access to your private key. Challenge-response, one-time-passwords, tokens, etc, etc. Putting it on paper is LESS SECURE than sticking it on a thunb drive. Then at least it can't be stolen by taking a picture...
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
http://en.wikipedia.org/wiki/Paper_tape Longevity. Although many magnetic tapes have deteriorated over time to the point that the data on them has been irretrievably lost, punched tape can be read many decades later, if printed on Acid free paper.
Also: http://obsoleteskills.com/skills/usingpapertapeforprogramming
It's lightweight and the readers can be dead simple: photo detectors using ambient light with the tape being manually pulled through the reader. If you want ultra reliability then use mylar plastic tape. The punches are more of a pain in the ass, but they are also not very complex.
The real win is that you get to play with the punch chad!
That's just the thing... a printed key is just one washing machine away from complete and total disaster at the data center.
He who has no
See http://www.mail-archive.com/gnupg-users@gnupg.org/msg10827.html.
The original paperkey software takes out the redundant key material for a smaller amount of data. You can restore the original key by combining the output with the public key.
To encode:
gpg --export-secret-key (thekey) | paperkey --output-type raw | dmtxwrite -e8 -f pdf > my_pdf_file.pdf
You can pass pdf, eps, svg, etc, to the -f option. Use 'dmtxwrite -l' to get a list of all supported image formats.
To decode:
dmtxread -N1 my_pdf_file.pdf | paperkey --pubring ~/.gnupg/pubring.gpg > my_new_secret_key.gpg
Did anyone else notice that the background image used throughout most of the video is a BSOD? Is this reverse-subliminal-advertising, or what?
Anyone ever heard about a smartcard? Generate the key on the smartcard, it never has to be exported (unless you want key recovery and escrow, in which case you need the CA to generate the key).
Last time I heard, 144k cards (GnD makes 'em, amongst others [Gemalto]) could store 4 2048 keys (a Java card has applets, an applet is basically a container on the card, which will define what size keys can be used/generated. Consider 'em partitions, but more complicated), so my guess would be that you could store a 4096 key without any problem, though, I've never seen it in practice.
I'll repeat this about... eight? times.
3.1415926535897932384626433832795028814973993751058
... until there's a 640kbit key. 640k ought to be enough for anybody.
But seriously, it was just a few years back when we though 128bit keys were unbreakably long. Now 2048bit is standard, and about to get broken. 4096bit isn't enough right now. 16kbit is just about right, but that will get broken in early 2015.
I'm going to need a new printer. One that I can run my post-it-notes through. Then I can print out this new bar code thingy and stick it on my monitor.
Never shake hands with a man you meet in a fertility clinic.
Does it come with a sticky backing so I can put it next to all the passwords I wrote down?
$ gpg --export | dmtxwrite --encoding=8 --format=PNG | lp
To be honest, I thought trusted paper keys were already common knowledge among geeks:
http://en.wikipedia.org/wiki/Trusted_paper_key
But how to store an 800-character key offline?
Uhm, 10 lines of 80 characters? 20 lines of 40 characters, if you think 80 in one hit might make you cross-eyed. Is it that hard to manually type in? For a backup copy that you will only ever be likely to type in once or twice, ever?
Or is this just another Slashvertisement(tm)?
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
You could just print a 256-bit random number on the paper. That feeds a keystream generator (AES-256-CTR, say), which is used as the random number source of a standard RSA private key generator. It would be relatively slow to regenerate your private key -- lots of primality tests and yadda yadda -- and the keygen code would have to have precisely specified cross-platform behavior so the same random number stream always produced the sameprivate key. But you could do it!
It's sort of the flipside of exchanging public key fingerprints: in both cases, a little fun with symmetric algorithms allows you to only print out a small private-key-sized number instead of a much longer asymmetric key.
Bottom line, the key needs to turn into machine-read data at some point in order to interface with the crypto system and unlock your data, no matter what. Moving it to a piece of paper doesn't make it any more secure than storing it on a read-only USB key that you only plug into your computer when you need to decrypt something, or a smart card.
In any event, if you really don't trust the PC, you have no business using it to decrypt anything at all. It'd be like entering your super secret PIN number at an ATM while some guy you don't know is standing right there watching you do it. As soon as it's decrypted any vulnerabilities of the host system can be used to gain access to the decrypted data.
You see? You see? Your stupid minds! Stupid! Stupid!
i think you're mixing up key length for symmetric ciphers (like AES, 3DES, Blowfish, etc.) which are generally quite short like 128 or 256 bits and key lengths for _asymetric_ cryptosystems which vary much more in length and in the case of RSA are somewhere closer to 2048 and 4096.
The reason is that for symmetric ciphers we _believe_ to be secure the best an attacker can do is brute force the key space. so that means brute forcing 2^128 or 2^256 possible keys. That's a hell of a lot of work. with current technology probably infeasible.
but for asymmetric schemes it's not as straightforward. To get a glimpse of why this is think about RSA keys. The public key is an exponent e and an integer n which is the product of two large primes. Now not every string of 4096 is actually represents such a pair number of numbers. (in particular not every bit-string is the product of two primes). so not every string of that length is a valid key. so brute forcing the key space doesn't mean trying every possible string of that length. just the ones which are the product of two primes which is a fair bit less.
Another reason for comparatively longer keys is this. In generally, for many asymmetric cryptosystems there are various attacks known which are still super-polynomial (i.e. inefficient) but are never the less sub-exponential which is what a brute force key search would be. so you have to adjust your key length to reflect these faster attacks even if brute forcing wouldn't be feasible even for shorter keys. (i think some examples of such attacks for factoring (which would break RSA) are the Pollard-Rho method, varients of Quadratic Sieve algorithm, and the Eleptic Curve method.)
Unless you can inspect the entire source code of your digital camera and/or scanner, you cannot guarantee that it's not modifing the image. Thus it's the weakest link in the security system.
How is this really all that different from using paper tape?
Give me a second while I print that thing on thermal paper...
Geesh, in base-64 it's only 683 characters.
Typed out at 65 characters per line that's less than 11 lines of text. Big deal.
Any halfway-decent OCR program should be able to read that error-free, assuming you don't spill coffee on it first.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
Isn't that what post-it notes are for...?
I can see some use for this a secondary method of archiving the private key. Perhaps one that might survive the EMP blast from a nuclear strike. I don't think I wouldn't trust it as a primary method though.
Personally, I would think that using a smartcard (or two for redundancy) would be a better option. Since the private key never leaves the card once installed, it can't be copied without stealing the card itself. The actual signing, or en/decrypting of symmetric keys happens securely within the smartcard. If someone actually needs to recover some encrypted archive data then they go get the card and use it. The pin to unlock the card can be changed as needed. Otherwise with typical removeable media or hard copy of the private key, any person or software that had access in the past could have copied it.
For an example of a large entity doing this full-scale, just have a look at the DOD CAC program.
Never underestimate the bandwidth of a truck full of tapes hurling down the highway
Is that some kind of metaphor for the internet?
I'm getting tired of this too.
PaperBak anyone ? http://ollydbg.de/Paperbak/
It gives you this kind of prints:
http://sebsauvage.net/i/ccm/paperback_a4.png
http://sebsauvage.net/i/ccm/paperback_detail.png
I save my private GPG key on paper this way.
... you fold the paper your 2D key is on? Tears, that's what. Tears.
Yeah, paper is quite a stupid medium for a key, I mean really, paper? The thing that can be folded, erased, burned, it can fade, get wet...
Why not a real key? A physical object made of metal or plastic that actually looks somewhat like a key? I know that not everyone can print metal at home but you can "print" a metal key at your local mall and vinyl cutters are getting less and less expensive (you should probably xor the crypto-key with a password, for additional security, if you use someone else's printer). Maybe it would be even possible to make the information stored on the key retrievable by scanning the object with a home scanner.
I was searching this kind of information after the recent Digital Dark Age topic: http://hardware.slashdot.org/story/10/02/23/2210224/Avoiding-a-Digital-Dark-Age
I'm looking for a way to store digital info for years. There has been many /. stories about this. /. crowd for giving all those clues about 2D codes printing and reading !
My conclusion: go for printed 2D codes with CRC like Reed Solomon, using archival paper and ink jet.
So thank again
My contribution:
Beware of those laser printing ! Solid ink can be peeled of the paper, leaving a blank page (with heat, time, vibrations, frictions). Prints last longer with quality ink jet prints, some are also water resistant.
BTW, does anyone have some good advice for the printing itself ?
I punched my private key onto 80 column punched cards for offline storage back in 1979. It was the only way to keep a key private on a mainframe where the operator could read all files.
I like a little alliteration in my catchphrases. How about:
Void thine vellum!
Oust thine onion skin!
And that's about all I can come up with.
Except maybe "Shit the sheet", but that doesn't sound as nice.
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
By the time that 2D barcodes get this huge, it's probably better to invest in proper character reading devices.
Religion is what happens when nature strikes and groupthink goes wrong.
Make a song out of it as for emergency numbers : http://www.youtube.com/watch?v=RK4Xye7AErE
Here is the RSA2048 number printed twice on a US letter paper. Tell me if you have an problems reading this:
http://drop.io/9x9qo5p
http://drop.io/9x9qo5p/asset/screen-shot-2010-03-04-at-10-04-40-am-png
http://drop.io/9x9qo5p/asset/document1-pdf
-- I was raised on the command line, bitch
What's so hard about adding checksums and/or printing the whole thing twice or three times?
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
If you care about key security then you have to use a Hardware Security Module (HSM). This concept is just absurd.
Oleh Yushuk did it long ago - http://www.ollydbg.de/Paperbak/index.html
just save your key to a text file, print it with paperbak.
Drop thy document.