Quote from: DannyHamilton on December 28, 2012, 04:30:02 PM

It might be possible that weaknesses/flaws are eventually found in SHA256, ECDSA, and RIPEMD-160 which would break the cryptography used by bitcoin, but without discovering flaws it will never be possible to brute-force a private key until computers are no longer made of matter, and no longer use energy to operate.

I wouldn't discount the possibility that this entire class of "bit-mixing" message digests may be broken some day. A brute-force search will not need to search a 256-bit key space. Successive breaks of the cryptography may significantly narrow that search space. Besides, you don't even have to search the whole 256-bit key space. There are numerous private keys that all produce the same Bitcoin address, and you only need to find one of them to claim the funds at that address.

Quote from: DannyHamilton on December 28, 2012, 04:30:02 PM

As far as I know, the SHA256 algorithm is not vulnerable to quantum computing, but I suppose that if someone happened to reuse an address and then lost the coins so that their public key is known, in that special situation if quantum computing ever reaches significant enough abilities, it might be able to crack a private key. But we are talking about an analogy closer to gold that has been pushed below the crust of the earth at a tectonic subduction zone than sitting on the bottom of the ocean.

I didn't say anything about quantum computing. Indeed, SHA has not yet been shown to be vulnerable, nor has ECDSA. I don't make the mistake of assuming that they are not vulnerable, however.