One of the biggest fears of Bitcoin users is that they will one day wake up and find their virtual wallet empty, meaning that someone has somehow managed to reveal the user’s private key. A Bitcoin private key is a secret number that acts as a kind of traceable “ticket,” allowing the coins held in the corresponding wallet to be spent.
Since 2010, it appears that around $500 million worth of Bitcoin, with around 6.6% of all Bitcoins in circulation in the hands of someone who stole them. With statistics like this, it's only natural for Bitcoin users to be concerned about the security of their private keys.
Speaking at HITB 2014 in Malaysia, security researcher and cryptographer Filippo Valsdora explores how weak signatures, if found on the Bitcoin blockchain, can be used to reveal the private keys of unsuspecting users. In his talk, he highlighted not only how the signature flaw can and has been exploited, but also ways that Bitcoin wallet providers can design to prevent breaches, reducing the chances of private key compromise. He also provided a list of Bitcoin wallets that have been proven to be the most secure, using the more secure ECDSA process.
More here.
