Quote from: sidhujag on November 07, 2016, 11:48:01 PM

Quote from: iamnotback on November 07, 2016, 02:57:11 PM

Quote from: Come-from-Beyond on October 20, 2016, 07:37:39 PM

Quote from: RealBitcoin on October 20, 2016, 07:12:01 PM

If my idea is worthless, then it strengthens the point why ECDSA is needed, and people will apreciate ECDSA more.

Your idea is not worthless and is already used in one of the altcoins. It's actually a nice solution for IoT-friendly cryptography for which ECDSA is too "heavy". The only requirements are to wait long enough between beginning and committing a transaction and to not reuse addresses (private keys).

Or you could use Winternitz (Lamport signatures) with Merkel trees for a more robust solution that doesn't reveal the private key and has roughly 1/20th the resource overhead (not including hardware acceleration of SHA256) of the most efficient (curve25519) elliptic curve cryptography (not factoring in batch mode). But the major downside is the size of signatures increase exponentially with increasing bit security level, which is also the problem with RSA. The theoretical gain is future quantum computing resistance, but research is proceeding on elliptic curve (isogenies) variants which are quantum computing secure.

There are many reasons why this makes sense... the generation time to create new signatures using Lamport + Merkle is negligent as that is amortized by the client which can afford the extra time for improved security. The signing is up to 10x faster but at the cost of higher bandwidth requirements like Anonymint says.

It is not just bandwidth, but also storage and cache coherency issues for performance. Also the performance advantage declines (is it exponentially?) as bit security increases. So eventually elliptic curves will have no (at least theoretical) resource cost disadvantages. Perhaps the one big advantage right now is (at least hypothetically although I don't know if anyone tried it) servers can employ SHA-256 ASICs for orders-of-magnitude hardware acceleration, and afaik ASICs for elliptic curve cryptography (ECC) are not mass produced.

Winternitz can compress the signatures in exchange for more computation. If the validation server-side it with SHA-256 ASICs (re-purposed Bitcoin mining hardware), it might still be much faster than unaccelerated ECC and with commensurate size at current recommended bit security levels.

However, it might limit compatible hosting for full (validating) nodes of such a design if Bitcoin mining hardware is not a standard offering.

Looking out the future 10 years when bit security levels must increase, perhaps ECC isogenies are ready for real-world usage.

Quote from: sidhujag on November 07, 2016, 11:48:01 PM

However the upside is favorable as it creates a quantum resistant system that doesn't need a bunch of one way hashing to "work-around" the problem of ECDSA.

The hash of public key (to create a BTC address) to mitigate any crack on ECC seems reasonably effective, unless it can be cracked in the period of time it takes for your spend transaction to be confirmed. Combined with a Finney attack it might be theoretically vulnerable.

Quote from: sidhujag on November 07, 2016, 11:48:01 PM

Another benefit you get from this is that Bitcoin requires one-time use addresses because those public keys once seen on the network can be used to steal balances by NSA once ECDSA is compromised so all spends with change are sent to new addresses with pubkeys not published yet.

Good point about why discarding public-keys on each spend are important for ECC. I had always thought (without really studying it carefully) it was for recommended for pseudo-anonymity (and perhaps some optimization of representing UXTO?), but your point is also valid.

A speculative counter-argument could posited that given widespread open-source and research sharing in today's Internet world, breakage of ECC is likely to come about in stages and so thus the improvements to ECC, so the risk of actual catastrophy is quite astronomically improbable. In other words, with so many public eyeballs looking at the issues, it is unlikely we will be publicly surprised.

So are you arguing for a persistent public-key or for not employing Merkle, so that each public-key is only (securely) one-time use?

Quote from: sidhujag on November 07, 2016, 11:48:01 PM

Because of this there is lack of usability on services that build upon the transaction creation process. For example in Syscoin I wanted to have an identity system (aliases) that would keep balances like accounts. To avoid mangled code to detect which addresses belong to an alias as change I simply removed the need to create new pubkeys for change and send change back to the alias pubkey which are public on the network.

Ah I see you want the persistent public-key for a balances design to avoid the complications of a DAG-like UXTO.

But isn't there another way to make one-time spends more user-friendly wherein the published payto identity remains constant, while the current address is allowed to change. So the spending client needs to access the blockchain before signing to grab the current address for the payto identity. I guess that has a race condition though and thus I am doubting your contention that Bitcoin is aiming for one-time spend address. Rather I think they recommend retiring old publickeys for maximum security, but it is optional right? Perhaps my idea could be combined with Bitcoin's principle for a user friendly automatically secure design. On further contemplation, in an appropriate balances design the payer perhaps doesn't need to reference the current address only the payto identity. The payee can spend from the balance that exists using the current address in the blockchain for that identity. This probably has holistic interactions and ramifications, so needs to be studied carefully. Note this is roughly the design I was implementing when I paused my work to work on a new programming language.

Quote from: sidhujag on November 07, 2016, 11:48:01 PM

The multisig feature of bitcoin lacks clarity and usability because of the design of bitcoin because pubkeys cannot be published and thus redeemscripts need to be saved and sent across potentially unsafe communication lines...

Interesting point that I was not aware of. I don't understand why publishing the hashes of the pub-keys is not sufficient? Are you referring to some cryptographic scheme such as where we blind who signed with a M-of-N ring signature? I haven't studied multi-sig.

Quote from: sidhujag on November 07, 2016, 11:48:01 PM

(read my multisig post here: http://syscoin.org/multisignature-identity-system-syscoin-2-1-technical-update/) with aliases I also save a redeem script for multisig alias identities so that any spending can be done without the need to transmit this information to each other (increases usability exponentially). The reasoning behind these changes were that if ECDSA were to be compromised Bitcoin would have a situation where they would probably fork it in as quickly as possible and choose the best implementation... leaving the need for one-time use addresses null and void which would mean my implementation which is one of simplicity actually is the optimal solution. Since I am not a cryptographer I'm not going to bother trying to change the implmentation although it shouldn't be too hard to figure out, just for lack of time to do other work but it makes total sense for long run that either Bitcoin through their new soft-fork voting mechanism or a potential coin supplanting Bitcoin would use something like this to overcome quantum computing.

Perhaps you could rephrase that summary because I didn't grok it. But i didn't read the linked blog post yet.