Quote from: achow101 on July 15, 2017, 09:49:40 PM

Quote from: KeepingScore on July 15, 2017, 08:47:54 PM

If someone breaks SHA-256 they'll be able to break SHA-512 in short order, relatively speaking. The orders of magnitude beyond what's being done right now say it's so. All avenues for modern cracking point to quantum state side channel attacks being the most likely candidates. Deriving a means of bypassing locks isn't what I'm referring to. And since hardware wallets rely on ECDSA for the most part (512 bits in some cases, re: BIP39), breaking SHA-256 definitely does have bearing. Standard cryptographic models aren't going allow it to be broken, but novel ones will. The fact that entropic quantum entanglement and the entanglement measure is an NP-Complete measurement means that no one's been able to look at it, except in novel effects-related efforts. I'm currently looking at electromigration as a candidate for bearing said data as it's related directly to quantum discord. Call it irrelevant if you like, but the security-level for bitcoin is based upon standard models, not taking into account measures that are outside of the boundaries. We've seen that bitcoin blocks can be falsely generated with the initial genesis block, and derive from there. Yes, that's a straw man for now, but that fact doesn't negate the weak foundations. Again, call that irrelevant or also un-prove-able. If I had a working model I'd be sitting in Maui. So, "pics or it didn't happen" all you want, I'll just leave this here so someday when it occurs I can refer back to it.

I never said that SHA512 is unrelated to SHA256 nor did I claim that SHA-2 functions won't be broken in the future. What I said is that these hash functions are unrelated to private keys. Can you explain how you would get private keys from public keys if SHA-2 were broken? What data in the blockchain, other than public keys, private key for a public key? What data related to hashes in the blockchain can get you the private key to a public key?

Getting the private key from a public key requires breaking ECDSA, not SHA-2. Even if you got a private key, you can't get the master private key or any other private keys in an HD wallet unless you also have the chaincode, but the chaincode is never put on the blockchain.

Unrelated to the functions as in not used, yes, but equal in strength is equal in strength. Again, I'm not talking decryption of public->private keys being a be-all solution to cracking wallets, but the level of strength is near or at the same levels, regardless of the protocols used. If you want to talk about ECDSA and cracking chains, let's talk hardwallets, going back to the original topic at hand. It's just as hard as SHA-256 and SHA-512 respectively in ECDSA. If SHA-XX2 were broken, the equality in entropy when using BIP 39 12x and 24x word wallet is therefore breakable as they're the same level of hardness, and would generate the master key and all subkeys for the hardware wallet, and mnemonic wallets. Deterministic wallets are a failure.

As for brute force and similar cracking methods, reducing the amount of space needed to be searched to find a viable wallet is the aim of either attacks. It needn't be an attack against an individual wallet. If security precautions are taken to upgrade bitcoin further in the future, only legacy wallets will have this issue. So long as you're relying on low bit-length codes, in either SHA-XX2 or ECDSA they'll be broken. Next Generation Encryption methods aren't extended at the moment because people see no need. Collisions against cracked private keys shorten the space yet again, yielding a limited space to search for chaincodes. Analysis of transactions narrows this further. People like to quote the "heat death of the universe" as in "hell will freeze over before that" but the reality is that shortening spaces in each case will lead to successful attacks unless the chaincode, too, is extended. And even then, human fallacy comes into play.