A New Class of ECDSA Signature Vulnerability Observed in the Wild on the Bitcoin Blockchain
"Our analysis illustrates how vulnerabilities in a custom ECDSA implementation can not only reveal private keys, but can also be used to compromise Bitcoin-pseudonymity and addresses to (online) personas."
https://www.nobsbitcoin.com/the-curious-case-of-the-half-half-bitcoin-ecdsa-nonces/