In August 2013, the Bitcoin community faced a significant security threat: the Android Bitcoin Wallet vulnerability, which led to the theft of 55.82 BTC. This incident highlighted the crucial role randomness plays in securing Bitcoin wallets.

The Root of the Problem

In the Bitcoin system, addresses, which are the carriers of Bitcoin balances, are generated through a seemingly straightforward process. A randomly generated private key, through irreversible computations, produces a unique address. However, the randomness of these private keys is vital for the security of the bitcoins. In 2013, a critical flaw in Android’s random number generator made it possible for two users to inadvertently create identical wallets, leading to potential theft.

Developer Response and Public Acknowledgement

Bitcoin developers quickly identified this oversight and issued a public letter in August 20131, urging users to address this serious vulnerability. Numerous news outlets covered this development2.

“All private keys generated on 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.” – Bitcoin Developers’s Official Warning issued an official warning about this vulnerability3, stating that any local random number generator could be affected. Impacted wallets included Bitcoin Wallet, BitcoinSpinner, Mycelium Bitcoin Wallet, and

Android’s Acknowledgment of the Issue

The core of the problem was traced back to Android itself. Android developers acknowledged their role in the Bitcoin theft incidents4:

“We have now determined that applications which use the Java Cryptography Architecture (JCA) for key generation, signing, or random number generation may not receive cryptographically strong values on Android devices due to improper initialization of the underlying PRNG.” – Android Developers

Impact on Users

Discussions on Bitcoin forums revealed the visible impact: 55.82 BTC were confirmed to be stolen. However, the total extent of the theft, including unreported cases, remained unknown5.


This incident serves as a critical reminder of the importance of cryptographic randomness in digital wallet security. The Bitcoin community’s swift response and transparent communication were key in mitigating the vulnerability and preventing further losses.