The Bitcoin Brain Drain: Examining the Use and Abuse of Bitcoin Brain Wallets

In the cryptocurrency Bitcoin, users can deterministically derive the private keys used for transmitting money from a password. Such “brain wallets” are appealing because they free users from storing their private keys on untrusted computers. Unfortunately, they also enable attackers to conduct unlimited offline password guessing. In this paper, we report on the first large-scale measurement of the use of brain wallets in Bitcoin. Using a wide range of word lists, we evaluated around 300 billion passwords. Surprisingly, after excluding activities by researchers, we identified just 884 brain wallets worth around $100K in use from September 2011 to August 2015. We find that all but 21 wallets were drained, usually within 24 h but often within minutes. We find that around a dozen “drainers” are competing to liquidate brain wallets as soon as they are funded. We find no evidence that users of brain wallets loaded with more bitcoin select stronger passwords, but we do find that brain wallets with weaker passwords are cracked more quickly

Replication Data for: The Bitcoin Brain Drain: Examining the Use and Abuse of Bitcoin Brain Wallets

In the cryptocurrency Bitcoin, users can deterministically derive the private keys used for transmitting money from a password. Such “brain wallets” are appealing because they free users from storing their private keys on untrusted computers. Unfortunately, they also enable attackers to conduct unlimited offline password guessing. In this paper, we report on the first large-scale measurement of the use of brain wallets in Bitcoin. Using a wide range of word lists, we evaluated around 3.9 trillion passwords and passphrases. Surprisingly, after excluding activities by researchers, we identified just 1,730 brain wallets worth around $261K in use from July 2011 to February 2017. We find that all but 21 wallets were drained, usually within 24 hours but often within minutes. We find that around a dozen “drainers” are competing to liquidate brain wallets as soon as they are funded. We find no evidence that users of brain wallets loaded with more bitcoin select stronger passwords, but we do find that brain wallets created with passwords rather than passphrases are cracked more quickly

Turning Around theL-Phe-D-Oxd Moiety for a Versatile Low-Molecular-Weight Gelator

We have prepared a small library of 13 peptidomimetics containing the L-Phe-D-Oxd unit (or the isosteric L-Phe-D-pGlu unit), which is a privileged scaffold for the preparation of supramolecular materials. These compounds were prepared in solution in excellent yields and tested as organogelators and/or hydrogelators at 10 mM concentration with a plethora of solvents and solvent mixtures. Two molecules were very efficient gelators: one is a organogelator and the other is a hydrogelator. As these compounds have quite different skeletons, a rationale to explain the different behaviour of these molecules as gelators takes into consideration their hydrophobicity, expressed as logP. Finally, Fmoc-L-Phe-D-pGlu-OH (6b) efficiently gelated phosphate-buffered saline (PBS 1X) at 1.5% w/w concentration and is an excellent candidate for the preparation of novel materials for applications in, for example, drug release, biological assays, and tissue engineering