The primary factor in a financial or private commerce ecosystem is secure communication between parties.
Jamming chat, etc., in a wallet is a poor attempt to conflate different types of information exchange. In a true trustless and anonymous transaction protocol, the information is a shared secret between sender and receiver that allows the receiver to prove a transfer of ownership.
You may think to yourself that chat solves this problem. Namely, sender and receiver set up an encrypted channel and exchange the secret. That can work great, but you don't need zk proofs in this situation. zk proofs solve the problem of ever exchanging the secret in the first place. So you don't need chat. I.e. it's cryptographically irrelevant.
Chat also has the problem that the sender and receiver need direct communication to exchange the secret. That's horribly limiting: "Hey Ted, we need to exchange some money, when are you available to do that?" At some point, the conversation has to be initiated on the private channel. So sender and recipient have to meet and exchange a secret to meet up on the channel. It defers the problem and so you still haven't solved it. Again. Chat, etc. become irrelevant because of this need to establish the private channel.
Also, zk proofs are good to solve the problem of exchanging a secret because it eliminates the need of the exchange. But stealth addresses already do that. So why implement zk proofs to solve a problem already solved by the
coin that you cloned from (vertcoin)?Right now, for crypto, zk proofs have been promised for zerocoin (zk=zero knowledge). But zerocoin is being worked on by people (1) smart enough to conceive of it, (2) smart enough to provide a public blue print giving enough information for one to determine where the proof fits, and (3) smart enough to know that even with this blueprint, they are still going to beat anyone who tries to implement their idea.
Hence, my conclusion (for which I can find no contradictory evidence) is that the shadowcoin dev borrowed "zk-SNARK" from the zerocoin whitepaper in the hopes that they make a release and he can clone the technology into shadowcoin.
I have no doubt that the SDC dev can pull this off. My doubt lies completely in with the zerocoin team in that they have conceived of an idea that is impractical to implement and therefore impossible to clone because it will never exist.
A)
Vertcoin's stealth addresses are closed source.. Shadow authored ShadowSend's stealth code, it's own dual-key implementation not cloned from any coin. Unlinkable and untraceable are two separate things. Stealth Addresses help with unlinkablity (creation of addresses not linked to their main public key).
B)
Shadow isn't implementing zerocoin or zerocash, and I would hope that they(ZC devs) would be able to beat anyone trying to implement their idea (ZC). The underlying technology in zerocash is zk-SNARKs, this doesn't mean that Shadows devs are borrowing or cloning any of their code. Also, the current Zerocash blueprint isn't a final representation of their model, it dates back to May and Dec respectfully. zk-SNARKs was not invented by zerocash and has yet to be implemented into a cryptocurrency. Shadow's SNARKs implementation is it's own protocol. I initially thought coming into this project that it was a ZC implementation until Ryno corrected me in IRC and explained the differences in their method. That's when I got excited and started focusing this as my long-term crypto investment.
As for the reasoning behind zk-snarks and stealth addresses it is part of the ShadowSend protocol and you would need to speak with Ryno for a more detailed explanation of how they will be tied together.
C)
"Chat also has the problem that the sender and receiver need direct communication to exchange the secret. That's horribly limiting: "Hey Ted, we need to exchange some money, when are you available to do that?" At some point, the conversation has to be initiated on the private channel. So sender and recipient have to meet and exchange a secret to meet up on the channel. It defers the problem and so you still haven't solved it. Again. Chat, etc. become irrelevant because of this need to establish the private channel."
There has to be some medium of negotiations or communication outside of the actual transaction. Otherwise there would just be something like a smart contract binding both parties to the deal without there being a convo before hand or in the case of a crypto exchange where communication is irrelevant between buyer and sell. The underlying concept of the ShadowChat is still the same: two addresses exchanging information. In a perfect world there wouldn't need to be a line of communication between parties, but unfortunately this isn't a perfect world and there is still an element of interaction in business relations i.e. shipping, transaction details, item questions, pseudo-invoicing, graphic design changes, etc. Negotiating a deal in a private room and exchanging information between two anonymous parties (ShadowChat) then using zk/sa to send funds(ShadowSend) leaves no trace of the transaction to outside parties, except the two involved. I wouldn't go so far as to say it's "irrelevant" because without a secure line of communication you rely solely on traditional means of communication: e-mail, chat, phone, forum posts.
This is the exact same concept that is applied on Craigslist, arguably the biggest grey (new and used items) and black market (stolen items, drugs, prostitution through code words which is a form of cryptography) on the net (also monitored the most), but in a more primitive manner. I have product A listed, you want to buy "A" from me. I list a method of contact: phone, e-mail, text. You use one of those lines of the communication to arrange the deal: time, price, date and location. The actual transaction is done with cash leaving no trace of the deal outside of the initial lines of communication or if the deal was under surveillance by the 3rd party.
In this sense you can look at ShadowChat is a method to replace those contact methods further reducing a potential man-in-the-middle attack. Leaving the actual transaction traceless (ShadowSend).
ShadowChat = Negotiations, Planning, Communication
ShadowSend = Exchange
D)
As far as "borrowing" the idea from ZC, almost all technology is borrowed from an originating source and credited. ZC (Ian Miers, Christina Garman, Matthew Green, Aviel D. Rubin) borrowed SNARKs from the original authors of the concept (
http://www.iacr.org/cryptodb/archive/2011/CRYPTO/video/rump/1d53ee327ee49f4afdbac8ed3b013657.pdf). Shadow looked at ZC's proposal and thought of a better proposal completely different from ZC. It wouldn't be the first time that technology has been improved on by an outside source.
Feel free to hop on IRC devs are online pretty much 24/7 #shadowcoin
