user32668: Suppose someone has single private key, and from that private key he made a public key for Bitcoin, Ethereum, Dogecoin, etc. - is it possible to figure out the private key having those multiple public keys?

user23123: It depends on how many times that private key has been used and whether the attacker has access to a side channel. Practically speaking if the attacker does not have access to a side channel and does not know a vulnerability in the secp256k1 curve (there are no known ones), then no, it's not practically possible to figure out the private key.

32668: <p>Suppose someone has single private key, and from that private key he made a public key for Bitcoin, Ethereum, Dogecoin, etc. - is it possible to figure out the private key having those multiple public keys?</p>
 23123: <p>It depends on how many times that private key has been used and whether the attacker has access to a side channel. Practically speaking if the attacker does not have access to a side channel and does not know a vulnerability in the secp256k1 curve (there are no known ones), then no, it's not practically possible to figure out the private key.</p>
