In a world of bitcoin any address could be anyone, but as addresses are shared (or posted on someones public website) knowledge is revealed about who they are. You can, thanks to how bitcoin works, track all the transactions they do and who they send it to. You may know somehow who the other side of the transactions are (or find out in the future, since the blockchain is forever).

This isn't how cash works, which is the real "money" in our system. At some point (even if on credit) cash is transferred for stuff. I don't want people to know which places I have a news subscription for. I don't want them to know who I donate to just from the blockchain. I have a choice to want them to know that. This is a practical problem because that means either I need to use shady services to hide these facts for normal purposes. That, or never use them except in a few cases where I don't care people know (but I also might regret that).

I think from a practical perspective, this makes bitcoin really hard to use. How do you make transactions that aren't easily traced to you by literally anyone? Answer: it's hard and possibly won't work completely.

> "I don't want them to know who I donate to"

This part seems to be the major problem zcash solves from what I can tell. Delivering on the promise of true anonymity which Bitcoin currently lacks. I see the appeal to current Bitcoin users, but outside of that group, can't see the appeal in a broad "general consumer" sense.

zcash seems like a company addressing a small problem (true anonymity) in the broader context of issues cryptocurrency faces (ubiquity, liquidity, ease of transacting, fraud prevention). Creating an entirely new currency which has to retread the efforts of building out the ecosystem to support that currency is a huge mountain to climb.

According to Matthew Green, they tried for years to get this (or one of the earlier versions) into Bitcoin and Bitcoin weren't having it. Their options were to make an entirely new coin, with the problems you point out, or to let the crypto they had developed die.

That's simply not true. I was actually hired as a consultant by Green, and he did hardly anything with that contract. I know of no proposal actually made to any Bitcoin devs for inclusion, and in any case, it took a long time to improve the tech to the point where resource requirements were low enough for either Zerocoin or Zerocash to be viable in any currency.

I went and dug up where I had read Green talk about this and it turns out it was in a conversation with you.

It seems you and him disagree, he says ZCash couldn't/wouldn't have happened in Bitcoin and you say it could.

Is your blog post about this still coming?

https://twitter.com/matthew_d_green/status/78153309118155571... https://twitter.com/matthew_d_green/status/78154154453702656... https://twitter.com/matthew_d_green/status/78154374789720064... https://twitter.com/matthew_d_green/status/78153489377171865... https://twitter.com/matthew_d_green/status/78154782708016742...

> I went and dug up where I had read Green talk about this and it turns out it was in a conversation with you.

Ha!

> It seems you and him disagree, he says ZCash couldn't/wouldn't have happened in Bitcoin and you say it could.

Yeah, I'm just surprised he feels so strongly about that, given how little I remember him actually doing along those lines. Like I said, I actually was hired by him on a monthly retainer to do consulting... and he did almost nothing at all with that contract. :(

> Is your blog post about this still coming?

Yes, although holy fuck I have a lot on the todo list. :( I also need to writeup my part of the trusted setup ceremony too.

And a blog post on that isn't paid work, so doesn't get as high priority as paying rent. :)

I can see the tension there. In a certain sense it's a shame to see good crypto languish.

It's also highlights why I feel the concept of a "decentralized" currency is essentially impossible. Someone always controls some facet of it, be it features of the currency, supply, restrictions, or value.

In the case of cryptocurrencies, the authors of the protocol and governance put in place to maintain it are the central authority. For zcash, the central bitcoin authority (whoever you referenced as 'Bitcoin') wouldn't/couldn't integrate features they wanted so they rolled their own currency of which now THEY are the central authority.

> According to Matthew Green, they tried for years to get this (or one of the earlier versions) into Bitcoin and Bitcoin weren't having it.

Can you cite this? If he said said it-- it's an outright lie.

Very true, but at least it's open source and can be used in other future coins. I never will claim to be a crypto, currency, or econ expert, but I think it's safe to claim it's still very early days for cryptocurrencies.

It's only hard to use if you care about those things, and aren't willing to simply "cash out" when you want to spend on other things.

You cash out because cash has this property. And, at least in the US, you never need to subject your self to daily currency fluctuations to go about your business. IF a crypocurrency is going to be used it needs to be able to be used as is on it's own just as easily as US Dollars are used now.

Why?

The best use cases I think of are definintely not "first world problems."

Places with no banking infrastructure.

Places with bad government.

Places with capital controls.

Does any cryptocurrency have banking infrastructure?

If you're counting "people who hold on to your money and promise to probably give it back", I'm pretty sure you can find some of those in most countries.

This may help answer it:

http://zerocash-project.org/q_and_a#what-is-bitcoins-privacy...

I could see one problem it could solve: donating to organizations that governments find "undesirable", like say Wikileaks, Manning/Snowden defense fund, or even the EFF, and then would take secret (or even more direct ones) actions against me (IRS audit, no-fly list, etc).

imho, it's important because a cashless economy is coming. And with how we've built everything up to now, a society running a cashless economy is ripe for dystopic control if the wrong person gets the reigns.

These technologies are about resilience in the face of rare but probable hiccups in social order. It's long-term investment and not about a killer feature that a single individual might crave :)

games, gambling, sexual things, anything that is in a gray market. many traditional payment services and hosting providers prohibit you from hosting sites with those. and some endusers who wish to spend money on things like gambling sites would like to do so anonymously, or have a payment option which is safer than handing strangers your credit card info and blindly trusting them.