Feeds

Android bug batters Bitcoin wallets

Old flaw, new problem

Providing a secure and efficient Helpdesk

Users of Android Bitcoin apps have woken to the unpleasant news that an old pseudo random number generation bug has been exploited to steal balances from users' wallets.

The Bitcoin Foundation's announcement, here, merely states that an unspecified component of Android “responsible for generating secure random numbers contains critical weaknesses, that render all Android wallets generated to date vulnerable to theft.”

Such wallets would include Bitcoin Wallet, blockchain.info wallet, BitcoinSpinner and Mycelium Wallet.

The problem is this: the elliptic curve digital signature algorithm – ECDSA – demands that the random number used to sign a private key is only ever used once. If the random number generator is used twice, the private key is recoverable.

This blog post, describing a presentation given at the RSA conference in March, gives a hint at what's going on. It described how the Java class SecureRandom (used by the vulnerable wallets) can generate collisions for the value r.

Moreover, r collisions appear to have been spotted in the wild as early as January – although the author of that post, Nils Schneider did not link the collision to SecureRandom.

According to The Genesis Block, SecureRandom was flagged by Google's Mike Hearn as the problem, in an e-mail to Bitcoin developers:

“Android phones/tablets are weak and some signatures have been observed to have colliding R values, allowing the private key to be solved and money to be stolen”.

Hearn says the Bitcoin Wallet app “has been prepared that bypasses the system SecureRandom implementation and reads directly from /dev/urandom instead, which is believed to be functioning correctly. All unspent outputs in the wallet are then respent to this new key.”

Given, however, the prior observations both of Bitcoin signature collisions and SecureRandom problems, The Register has asked Hearn if developers should have been advised to avoid SecureRandom sooner. ®

New hybrid storage solutions

More from The Register

next story
Google recommends pronounceable passwords
Super Chrome goes into battle with Mr Mxyzptlk
Infosec geniuses hack a Canon PRINTER and install DOOM
Internet of Stuff securo-cockups strike yet again
Reddit wipes clean leaked celeb nudie pics, tells users to zip it
Now we've had all THAT TRAFFIC, we 'deplore' this theft
Apple Pay is a tidy payday for Apple with 0.15% cut, sources say
Cupertino slurps 15 cents from every $100 purchase
YouTube, Amazon and Yahoo! caught in malvertising mess
Cisco says 'Kyle and Stan' attack is spreading through compromised ad networks
TorrentLocker unpicked: Crypto coding shocker defeats extortionists
Lousy XOR opens door into which victims can shove a foot
Hackers pop Brazil newspaper to root home routers
Step One: try default passwords. Step Two: Repeat Step One until success
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
Top 5 reasons to deploy VMware with Tegile
Data demand and the rise of virtualization is challenging IT teams to deliver storage performance, scalability and capacity that can keep up, while maximizing efficiency.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.