Bitcoin Private Key Necromancy

http://www.pxdojo.net/2013/12/bitcoin-private-key-necromancy.html

by sillysaurus2 • 13 years ago

199 96 13 years ago

splitbrain• 13 years ago

I guess this wouldn't work with an encrypted wallet.dat which was introduced later than 2011.

1337biz3• 13 years ago

Is there any tool to brute force/run password lists against wallet.dats? I have one around that I am adding coins to but just can't remember my own password.

liam_ja• 13 years ago

https://en.bitcoin.it/wiki/Wallet_encryption

It would be pretty unfeasible to attempt a brute-force, due to the number of encryption rounds.

nwh• 13 years ago

6 attempts a second on a high end i7 is as good as it gets. If you don't remember 90% of it then the coins are lost.

celticninja2• 13 years ago

why thye fuck would you keep adding coins to it if you dont know the password?

More likely you have obtained someone elses wallet.dat file that they have encrypted and they do not know you have a copy of this wallet.dat so they are still using it, and you do not know their key but would quite like to access their coins.

JorgePasada3• 13 years ago

Yeah the wallet in this post was created around version 0.3 or 0.4 of the Bitcoin client if I remember correctly.

ge0rg3• 13 years ago

I wonder how long it takes for admins at VPS hosting providers to start harvesting private keys from VPS instances, using this tool or, where available, direct filesystem access...

rmc2• 13 years ago

About as long as it'll take them to start harvesting credit card details from the same clients.

omh3• 13 years ago

Credit card thefts can be reversed.

If they can't detect which of the admins did it then what are they going to do?

yumcoin• 13 years ago

If you set up your VPS with a hierarchical deterministic wallet[1] or a passphrase-protected private key[2], your hosting provider will be unable to determine your private key.

[1] https://github.com/bitcoin/bips/blob/master/bip-0032.mediawi...

[2] https://github.com/bitcoin/bips/blob/master/bip-0038.mediawi...

omh3• 13 years ago

Is that still true if the attacker has access to system memory? That's a more difficult attack but still feasible for a malicious VPS admin.

lsc• 13 years ago

There's really no getting around the evil maid attack[1], if someone can attack your hardware directly. There's even evidence that a sufficiently clever attack can persist through formatting and re-installing a drive[2] - note, people have also found exploits in network firmware... remotely exploitable exploits. If you can do it by accident[3], then most likely it can be done with malice aforethought.

Edit: adding a strong pass-phrase /does/ give you a significant level of protection; While it doesn't offer protection from an evil maid type attack (where the attacker trojans your server, then you decrypt your key after said server was compromised) it does offer quite a bit of protection, say, from an attacker who has access to old backups but not your production system. So I think a passphrase on all of your important private keys is a worthwhile thing to have.

I just want to make it clear, once you decrypt that key from within a compromised system? all bets are off.

[1]https://www.schneier.com/blog/archives/2009/10/evil_maid_att...

[2]https://news.ycombinator.com/item?id=6148347 (of course, this specific attack wasn't as scary as it could have been, say if the same sort of thing was remotely accessible)

[3]http://theinvisiblethings.blogspot.com/2010/04/remotely-atta...

wikwocket• 13 years ago

This is similar to asking why more waiters/waitresses don't use credit card skimmers.

I suspect the answer is similarly that, unsurprisingly, most hosting providers are in the business of providing hosting, as opposed to running a front for criminal activities. And that anyone caught running this criminal activity would likely be fired and prosecuted.

And of course that there is an inverse correlation between the type of person interested in petty theft, and the type of person with the skills required to do this and not get caught.

vpsserver• 13 years ago

But it makes sense to retrieve wallets from instances that are going to be permanently deleted (when client stopped paying, etc).

For example it would save 17000 BTC that bitomat.pl exchange lost when upgrading Amazon EC2 instance to add RAM.

sillysaurus24• 13 years ago

I saw this post when the author submitted it to /r/bitcoin several hours ago: http://www.reddit.com/r/Bitcoin/comments/1t5fgr/i_wrote_a_to...

Frustratingly, the author titled his post "Bitcoin Private Key Necromancy" but titled his Reddit submission "I wrote a tool to pull private bitcoin keys off dead harddrives" which is a far better title.

He recovered about 46 coins.

kubiiii3• 13 years ago

If the hardrive wont power on but the filesystem is ok you can still send it to a recovery company for something like a few hundred bucks. -Hi i've just received the data you recovered from my hard disk, thanks, but I can't find my wallet ... -Dont know what you are talking about.

johnchristopher• 13 years ago

Last time I checked it was more in the thousands bucks range than in the hundreds unless you are only talking about damage controller.

MWil5• 13 years ago

I wish this could help me recover 3 btc I had in 2010 b/c I still have the HDD. My problem is that my disk is extra dead - it stopped spinning completely. I can't use hiren's boot tools with it like I could my other dead drives. I've heard I would have to bring it into a clean room environment for about a grand and have experts recreate the drive.

mctx• 13 years ago

I've heard success stories of transplanting platters into the same model working drive, maybe this is worth a shot?

paraxisi• 13 years ago

I have also heard/read about a few people doing this.

If I remember correctly, you need a special tool to pick the platters up out of the drive without rotating them, but aside from that just a new controller/assy.

ansible2• 13 years ago

I think it would be worth it first to just swap out the controller board on the bottom of the drive. If it isn't the motor itself, then that might fix the drive.

ajays• 13 years ago

Freezer? I've heard of HDDs that wouldn't spin up, were put in a freezer for 2 days and then spun up. They key is to copy the data off QUICKLY as it dies the moment warms up. So you can't go around doing a "grep -r -i bitcoin /" ...

FatalLogic2• 13 years ago

Be very careful about condensation if you do this.

KiwiCoder2• 13 years ago

I used to be cavalier about HDD disposal, and then one day I helped a friend recover some files from their apparently dead HDD. We did not recover the files but we did find unencrypted passwords to email accounts and other sensitive information that he had forgotten about.

So while I trust device/disk wiping tools are effective, I'm much less trusting of my own memory about the files on any given storage device. Moreover, and perhaps more importantly it's rarely possible to guarantee that software is consistently doing the right thing with your sensitive data.

Therefore my rule is now to donate unwanted hardware but never to donate or dispose of storage devices without being certain the data is unrecoverable. This is a harder problem than it might at first appear.

Secure disposal of hardware is a problem growing worse in proportion to the number of devices we allow (or by inaction permit) to manage our personal data.

sillysaurus24• 13 years ago

dispose of storage devices while being certain the data is unrecoverable

I use Derek's Boot and Nuke bootdisc for this purpose. http://www.dban.org/

It's straightforward to use, but it's also configurable if you want to be extra certain the data is gone. I think the default is 3 passes of filling the harddrive with random data generated via Mersenne Twister.

omh3• 13 years ago

Unless you're very paranoid then a single pass of zeroes should be sufficient.

The bigger problem is what to to with a dead hard disk. It's usually easier to buy a new one rather than replace it, but an attacker could perhaps repair the disk to steal the data. At work we send any non-wipable disk to be physically shredded. At home I think I'd just hold on to all disks indefinitely.

willvarfar• 13 years ago

These days there is a proper secure wipe built into most drives themselves. Its part of the ATA spec. https://ata.wiki.kernel.org/index.php/ATA_Secure_Erase

Yet if you ask how to wipe a disk on a forum, you'll get user-space ideas like `dd` and `shred` :(

KiwiCoder2• 13 years ago

To clarify - the hard part is not the destruction of data you know about, it's the identification of data on devices you don't know about, or forget.

Computers with hard disks are obvious, but also consider mobile phones, tablets, games devices (that increasingly ask for sensitive information), PVRs, and so on.

There may be a point, if we haven't already reached it, where I can't dispose of a toaster without worrying about how to wipe its memory.

dzhiurgis4• 13 years ago

How about cat /dev/random > file ?

pbhjpbhj• 13 years ago

DBAN's good, there are a couple of other ways I've used including dd.

Here's a blog post about it http://alicious.com/secure-drive-data-wiping/ including references to some papers where they looked at the probability/possibility of recovery.

DocG• 13 years ago

I am related to computer refurbishment charity company. We get also old stuff from other company's and it is always in contract, that hard drives must be at least destroyed mechanically.

No rewriting or deleting. Mechanical only.

We remove platters, break them. After that, the value of data is far less for these things than the cost of recovering.

driverdan• 13 years ago

SSD + full disk encryption = no data recovery. Even without full disk encryption the data will be gone pretty quickly with TRIM.

makomk• 13 years ago

Yeah, it's kind of a neat trick. I wrote a similar tool a couple of years ago though I'm not sure if it still works: https://bitcointalk.org/index.php?topic=25091.0

Shtirlic• 13 years ago

Thank you, I recovered some of my bitcoins with your tool 1 year ago.

JorgePasada3• 13 years ago

Oh cool, your that guy. Someone else brought up your tool at the meetup when we were talking about this post.

jrochkind1• 13 years ago

Oh geez, have upworthy-style "this guy" headlines come to HN?

chaz• 13 years ago

"This guy" has been here for years. :) https://www.hnsearch.com/search#request/submissions&q=%22thi...

jheriko2• 13 years ago

i don't get it... what exactly is the criticism here?

nashashmi• 13 years ago

I think 'this guy' makes it similar to a notorious outbrain paid advertisement: "this guy made money sitting at home"

jheriko2• 13 years ago

i'm pretty sure that once poor or greedy people can get 'day-to-day' value out of bitcoin beyond its pure monetary value as an investment (you don't want to hold onto your stolen goods in hope they appreciate in value) then we will start having many much more serious problems with its thievery...

smart and driven criminals will solve a lot of problems in ingenious ways you never thought of

Sami_Lehtinen• 13 years ago

Totally misleading post title, if you can read drive... It isn't dead... Got it?

graemian3• 13 years ago

Doesn't work for Bitcoin Wallet on Android :-(

I lost some Bitcoins on an old phone that used Bitcoin Wallet (https://github.com/schildbach/bitcoin-wallet) by doing "Settings > Reset".

I tried using this app to find them by dumping the /data partition, but no luck. Apparently it uses a different wallet format:

The wallet file format is not compatible to wallet.dat (Satoshi client). Rather, it uses a custom protobuf format which should be compatible between clients using bitcoinj.

Any ideas on how to find such coins?

sillysaurus24• 13 years ago

I like a good challenge. Would you send me a dump of the phone's harddrive? The command to dump the harddrive is `dd if=/dev/hda1 of=./phone.image`

Then I'll examine the bitcoinj wallet format and write a tool to search for the private key within the phone.image file.

My email's in my profile.

ge0rg3• 13 years ago

Haha, this is a nice try :D

romaniv• 13 years ago

I lost some Bitcoins on an old phone that used Bitcoin Wallet (https://github.com/schildbach/bitcoin-wallet) by doing "Settings > Reset".

That sounds like remarkably horrible UI design.

Being purely digital and having no institutional overhead, Bitcoin seems to "uncover" a lot of security and design problem in modern apps.

graemian3• 13 years ago

It was an Android "Settings > Reset", not from within the app

ansible2• 13 years ago

It may have made a new filesystem and written that to your NAND Flash or eMMC drive partition. So the filesystem itself won't contain any old data.

Depending on the type of filesystem used, it may have walked through all the blocks of the NAND Flash, erased them, and then marked them as 'ready for use'.

If you are very serious about this, your best bet is to (A) stop using the phone now, (B) dump the raw partition contents using the Android tools.

The situation might be better or worse if the phone uses eMMC, but the above holds. The chip itself does the Flash management (wear leveling, bad block detection, etc.). So it can hide more, but there may be leftover data from the old /data partition still in the unused blocks.

graemian3• 13 years ago

I'd love to know if the partition was completely wiped as you describe. It's a Galaxy S2 running Android 4.0.4. It's the /data partition on the internal storage, I think.

How would I find out?

mrb• 13 years ago

I wrote a tool one day (during a long car ride :D) to recover keys from Bitcoin Wallet on Android. It consists of searching for the header of the wallet-protobuf file (always starts with "\x0a\x16org.bitcoin.production") and then parsing the protobuf data.

Once the 256-bit private ECDSA keys were dumped in hex, I didn't even bother finding/writing a converter to WIF format. I just used brainwallet.org for that purpose (pasting the value in "secret exponent", and making sure to select "compressed" as Bitcoin Wallet creates compressed pub keys), then imported the WIF into a local bitcoind instance.

nullc• 13 years ago

Why would they spend time trying all those things and reinventing the wheel when a tool for doing exactly this has existed since time immortal (in bitcoin terms):

https://bitcointalk.org/index.php?topic=25091.0

Bitcoin Private Key Necromancy

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