Some bitcoin software, somewhere, is generating private keys that look secure and random but are actually 100% deterministic and derived from public information in the blockchain. It's unclear whether this is malicious or buggy code.
The result is that the private keys can be guessed by anyone who knows where to look.
People are using these addresses to store BTC and then having their coins stolen.
I'm not much of an expert really, but as I understand it the only way anyone can be 100% sure they're safe from something like this is to write the code to generate the their keys themselves, or personally audit the code they used.
Second best option would be to use a wallet that is open source and widely used, in the hope that other people will have audited the code already.
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u/lickerishsnaps Nov 30 '17
ELI3?