Oh and BTW, we support 3 form factors for the OtherCoin cards: microSD, Bluetooth smartcard reader and NFC (Yubikey Neo for instance). The microSD card can either be plugged directly into your smartphone or connected to the microUSB port if your phone supports USB storage (we'll bundle one of these: http://www.meenova.com/st/p/m3r.html with every card we sell, it's small, fits on a keychain and works great with the newer Android smartphones that have no microSD slot).

Hi guys, author of OtherCoin here (thanks Beeblebrox for the support, I've just noticed this thread),

Just to summarize and answer your concerns:

1. The OtherCoin smartcard does not hold your private key. It generates a private key internally and gives you the corresponding public key. Your wallet (under your complete control, even our sample is open source, see https://github.com/razvandragomirescu/OtherCoin ) generates a similar keypair (public + private key). The two public keys are added to become your Bitcoin public key (and address). The card never knows what you'll generate as your half (that's exactly how Bitcoin vanity address generators work, I have not invented this), so we cannot touch your funds

2. The security of the system comes from the tamper-resistant nature of the smartcards we use. If you have a GSM phone, you're already using one (your SIM card). If you have a chip and pin card (in Europe for instance), you're also using one. These are chips/devices designed to be secure against all sort of attacks, including physical ones (since they operate in a hostile environment, their users are the most likely attackers).

3. Whenever two OtherCoin cards talk to each other (using your smartphones as proxies - they have no radio capabilities or any other way of reaching another card), they establish a secure encrypted channel and then pass the Bitcoin "half a private key" that they've generated to the other end and at the same time destroy it from local storage so that the current user cannot reuse it.

So take a look at the Android app we wrote as a sample: https://github.com/razvandragomirescu/OtherCoin/blob/master/src/com/cayennegraphics/othercoin/OtherCoinActivity.java (look at line 661 to see how the two key halves are combined into one) and the demo movie at the system in action at www.youtube.com/watch?v=ZR8gz0uVBHk&feature=youtu.be . Feel free to provide feedback, cards will be available for purchase in the next couple of weeks.

Thank you! Received both payments. Will put them to good use, I accept the terms of the Gentlemen's Agreement, will do my best to make this into a commercial success, now that I also have the means to do it.

Thank you once again!
Razvan

Thank you Beeblebrox, will reply there.

Regarding the use of smartcards in Samsung Knox, here's Samsung's official response:


The app itself works fine but access to the smartcard is blocked by the Knox container. I do plan to work around it by having a hosted smartcard in the cloud (a physical one, plugged somewhere in your computer). That is planned, just not implemented yet.

Beeblebrox, I think I'm going to accept your offer. I've spent the past few days talking to various people and it looks like most of them do not really understand what OtherCoin is/does. They keep asking questions like "how is this different from spending Bitcoins between two Android smartphones" (as in using the Android Bitcoin Wallet to spend the funds directly via the blockchain) or "why do I need a microSD card in my phone to do this" (they don't know what a smartcard is or are even aware of how vulnerable an Android smartphone really is, especially when rooted).

On the other hand, distributors want to see a finished product (packaged, ready to sell) before they commit to anything, so I guess the first order of business would be to get these to look more "commercial", then into the hands of a few key people and reviewers that can understand how OtherCoin is different from a regular Bitcoin payment. I also need a demo video that shows the actual product in action, from the time you insert the card into your phone to your first payment through the system.

Just to clarify, is the 10 BTC part of your bounty still on (for when this becomes a commercial product, which should be in a few weeks)? If the 20 BTC loan removes the 10 BTC part of the bounty, I'd rather struggle to get it out the door on my own, then take the 10 BTC and use them on the project. As you can see, I am a bit reluctant to get into debt (managed to stay debt-free for 35 years ...) but I really believe in this idea and its potential.

You are also welcome to become more involved in the development/company if you wish to do so, I could use an adviser / partner, even if you don't want to do this in an official position (but also if you do).

Thank you,
Razvan

I've posted some initial pricing data and a few details on how to order a unit from our first batch in the Project Development area at https://bitcointalk.org/index.php?topic=319146.msg4494688#msg4494688 .

Hello again everyone,

I am looking for a few early adopters for the OtherCoin off-chain payment system - we're getting ready to order our first commercial batch from the hardware manufacturer, we're still ironing out the bugs and the UI and provisioning system, but if you'd like to play with one sooner rather than later, this is your chance. This initial batch will go for 0.35 BTC/unit, the final price will probably be lower but I'm trying to play it safe with the initial batch.

You can also get a pack of two for 0.6 BTC (which is probably a good idea since you need someone else with an OtherCoin to send/receive funds to/from). You're also going to need an Android phone with a microSD slot, with Android 4.1 or newer. OtherCoin supports Bluetooth smartcard readers and NFC, but the cgToken Bluetooth reader is just a prototype for now (we have one on loan from the manufacturer) and the NFC version is using the Yubikey Neo (we need to get a few of those as well, but we haven't really tested them as thoroughly as the microSD version).

Finally, if you are interested in becoming an exclusive reseller in your country (or region), please contact me at razvan.dragomirescu (at) veri.fi , in this thread or via PM and make us an offer. Please make sure you can promote this in your area (conferences, meetups, etc). We are looking for _exclusive_ resellers, this is your chance to secure distribution in your country or even your larger region (e.g. North America, Australia, China, etc) and support the launch of the OtherCoin at the same time. We are willing to entertain lower offers given that the product will take a few more weeks to be fully available, but this is no KickStarter project, the hardware is operational and the software works (as demonstrated in the YouTube demo I posted above).

If you have any questions, ask away. If you want to place an order or just show your support, send funds to 1VeriFivRsUxUqdWMgUmHrgfQXL9J3dfe and post here (or email/PM me) to indicate what you've ordered and where you want it shipped. Shipping is included in the price above, as well as VAT where applicable. If you need a VAT invoice, please mention that as well.

P.S. Resellers not only get the exclusive rights for OtherCoin in their area but also the rights to the Card2Coin sub-project (see https://bitcointalk.org/index.php?topic=339389) that will become part of the OtherCoin ecosystem, closing the loop by allowing the exchange of OtherCoin keys to dollars directly, without ever having to touch the blockchain. This is not ready yet, it's going to be operational this fall (around September).

Thank you,
Razvan Dragomirescu

S-a rezolvat, s-au miscat repede, au anulat tranzactia manual si au reaparut banii in cont. Bravo! Pina acum nota 10!

Don't worry, that's coming:). Just didn't have time to implement that yet. This will be useful for completely offline transactions (right now transactions are simply off-chain but you still need access to a way to verify the balance associated with a private key - right now we use the BlockChain.info API with a pinned certificate to prevent man-in-the-middle attacks, but OtherCoin will also support signed "balance statements" that certify that at the time of the signature the balance of that particular key was x BTC (and as long as the key travels only between OtherCoin devices, its current balance can only be higher since nothing can be spent without the private key that is held securely in the smartcard).

I've also looked into using SPV to prove to the recipient that the key actually has a certain balance, but as far as I understood, SPV is _not_ safe if your only source of information is the potential attacker. SPV should be safe if the majority of the nodes you have access to are honest and in the case of an offline transaction, the only node you have access to is the sender of the funds who is also the most likely attacker.

Salutare,

Am incercat sa anulez un transfer bancar pe BTCXChange.RO (user "drazvan") pentru ca mai schimbasem niste BTC in RON si as fi vrut sa retrag suma totala. Retragerea nu fusese inca procesata. Problema e ca acum transferul apare ca anulat dar suma respectiva nu a fost re-adaugata in cont.

Cum fac ca suma din transferul anulat sa imi reapara in cont (sau macar sa ajunga la destinatia initiala)?

Am trimis si un email catre BTCXChange dar am zis ca e o idee buna sa postez si aici.

Multumesc,
Razvan

OtherCoin is channel agnostic, I've implemented SMS and QR codes as samples but you can also use NFC, Bluetooth, WiFi or even the Internet. SMS appeared safer (especially if parties are on the same network - meaning that the messages only go through the SMSC of the operator and do not leave their infrastructure).

You can also mix channels if you feel like it (even in the current implementation, you can send your request via SMS but scan the response from the QR code, although I don't see why you would do that).

Thank you, 0.5BTC received as well. If the smartcard reader whitelist that Samsung support mentioned is real, I will try to work with our supplier to get the OtherCoin/cgToken Bluetooth reader certified with Samsung to make it usable in the Knox container. Their support guy didn't sound very sure about it though, they had specifically told me to only use Bluetooth 2.1 (not 4.0 - that's not supported) and never mentioned this "whitelist" until I actually tried it and saw the exception being thrown in their system classes (the app passed certification just fine).

I'm not sure if the split key setup is patentable (but I am not a patent attorney either) - after all, that's how the vanity Bitcoin address generation works. They are not storing the secret half of the key in a tamperproof smartcard though or using the system to securely transfer value between parties.

One other thing that is interesting is that OtherCoin is not limited to just Bitcoin - any altcoin that still has the notion of a private key (used to transfer funds) can be integrated with it. If the altcoin uses Elliptic Curve crypto, then the split key scenario also works, but you can also use the system without a second half stored in the smartphone and just trust the smartcard to transfer the private key around safely.

I would definitely like to claim the remaining 10 BTC from your bounty as well, what would you like to see before that happens? The Android app can be in the Play Store in a few days but it's not very useful without the hardware (the OtherCoin card) - additional OtherCoin microSD cards will take a few weeks to arrive. Please let me know how you see this. You can also email me at razvan.dragomirescu (at) veri.fi or send me a PM.

To everyone else reading this thread, if you would like to be appointed as the exclusive reseller in your country or region (considering that the solution is not currently patented and, as Beeblebrox mentioned, we are not sure if it is patentable at all), feel free to make me an offer - I'm also willing to consider offers that pay a reservation fee immediately with the rest of it being due at the time the application starts selling.

Thank you Beeblebrox, 5 BTC received.

I'm not sure what you mean by "public" - taking it commercial will take a bit longer (the main showstopper being the actual hardware - I have a few of each of the various hardware form factors for the OtherCoin card and obviously need to get some initial stock and selling these to end users requires various little details like a manual, a logo (engraved or silkscreened) on the actual card, a streamlined card issuance/provisioning mechanism (right now it's all manual and I don't scale very well ). I also plan to have a limited beta test with a few users just to confirm that I haven't missed anything obvious.

My plan for the coming weeks is to raise enough funds (either via donations such as yours or by preselling exclusive distribution rights) to allow me to focus on this project exclusively and take care of these little details before I go fully public.

The source code for the Android app has just been published at https://github.com/razvandragomirescu/OtherCoin - any interested party can take a look and verify that it actually works the way I described (keys are split between the smartcard and the phone, the card has no access to any network and communicates only to the smartphone, etc). It should also serve as a reference on how to interface with the various form factors that the OtherCoin will have (microSD card, external Bluetooth token or NFC token).

Regarding Samsung Knox, it already works with it. I've actually had Samsung wrap OtherCoin + the official Android Bitcoin Client + the helper tools for the Bluetooth OtherCoin and they all run from within the Knox container (tested on a Galaxy Note 2). The problem comes when interfacing with the OtherCoin card - Knox containers disallow communication to external storage (so no microSD or USB) and also block NFC. Only Bluetooth should work, but it doesn't (there's an exception in the BluetoothSocket system class - not in my code). I'm all over Samsung's support for this, they have specifically told me that Bluetooth should work but now they claim that only very specific "whitelisted" Bluetooth smartcard readers are allowed. But yes, it works in Knox, if you have a Samsung device that supports it let me know and I'll email you the wrapped APKs to try it.

Regarding user adoption, the plan was to get some early regional resellers that can help by promoting it at local Bitcoin meetups and conferences in their area. Preselling exclusive distribution rights (per country or per region) would also help us raise the necessary funds to turn this from something I'm working on in my spare time into a real business. I'm not sure where you are located, but if you're interested in acquiring the exclusive distribution rights in a certain area or country, make me a reasonable offer and I'll take it. You would not only get the exclusive rights for OtherCoin in your area but also the rights to the Card2Coin sub-project (see https://bitcointalk.org/index.php?topic=339389) that will become part of the OtherCoin ecosystem, closing the loop by allowing you to exchange your OtherCoin keys to dollars directly, without ever having to touch the blockchain.

Depending on how much we raise from early regional resellers, I might take those 20 BTC you've offered as a loan, I really appreciate the offer. Thank you!

(we should probably move the discussion to the Project Development area sometime, right now it's a mix of tech + project dev)

As promised, I've uploaded a more detailed demo of the OtherCoin system to YouTube at http://www.youtube.com/watch?v=ZR8gz0uVBHk&feature=youtu.be (make sure you view it in HD).

It shows it running side by side on a Samsung Galaxy Note 2 and a Vodafone Smart Mini (a.k.a. Vodafone 875), sending keys back and forth over SMS and interfacing with the Android Bitcoin Wallet to reveal a key (remove it from Othercoin and import it into the wallet) and add funds to a key (stored securely in the OtherCoin smartcard). Sending/receiving keys via QR code still works, it's just not shown in this video.

If you have any questions, ask away. If you feel generous (or supportive), 1VeriFivRsUxUqdWMgUmHrgfQXL9J3dfe .

Thank you,
Ravan

As promised, I've uploaded a more detailed demo of the OtherCoin system to YouTube at http://www.youtube.com/watch?v=ZR8gz0uVBHk&feature=youtu.be (make sure you view it in HD).

It shows it running side by side on a Samsung Galaxy Note 2 and a Vodafone Smart Mini (a.k.a. Vodafone 875), sending keys back and forth over SMS and interfacing with the Android Bitcoin Wallet to reveal a key (remove it from Othercoin and import it into the wallet) and add funds to a key (stored securely in the OtherCoin smartcard). Sending/receiving keys via QR code still works, it's just not shown in this video.

If you have any questions, ask away. If you feel generous (or supportive), 1VeriFivRsUxUqdWMgUmHrgfQXL9J3dfe .

Thank you,
Ravan

I have spent the past few days polishing the UI and adding the ability to send/receive the keys over SMS. I am deliberately trying to avoid sending the keys over the Internet in any way - to make the transfer less likely to be noticed by someone looking at Internet traffic. SMS goes only through the facilities of the GSM operators while QR code goes nowhere (it's strictly screen to camera).

I will try to post another demo movie in the next few days to show off the new UI (new icons, less text) and demonstrate an SMS exchange.

I have also deliberately avoided exchange protocols over NFC and Bluetooth to keep the technical requirements as low as possible and also to "free" those two wireless options for communication with alternative form factors of the OtherCoin (NFC is used if you have a Yubikey Neo with the OtherCoin software on it while Bluetooth can be used to talk to the cgToken form factor (external Bluetooth smartcard reader).

If anyone's interested, the OtherCoin is now a real product, see my announcement at https://bitcointalk.org/index.php?topic=321085.msg4371708#msg4371708 . There's also a (quick and dirty) YouTube demo video at http://youtu.be/YXGOGMnRx2Y .

Right now I am putting the final touches to the Android app before it's ready to be released as open source for anyone to reuse and integrate into Bitcoin wallets.

In other news, we've been named Runner Up in the Bionym idea competition (see http://www.getnymi.com/blog/first-round-winners-the-nymi-ideas-of-the-new-year/), so we'll be getting one of the first Nymi developer kits. Nymi is a biometric authentication bracelet that authenticates you towards other devices based on your ECG / heart rhythm - so you will soon be able to make OtherCoin payments and authorize them (literally) with a heart beat .

Finally, we're working with Samsung to get OtherCoin authorized for use in their secure Samsung Knox containers (https://www.samsungknox.com/en). Android applications running inside Samsung Knox containers are isolated from the rest of the phone and protected against malware, so you should feel safer transacting Bitcoins that way. Of course, Samsung Knox only works on Samsung devices (recent ones like the Galaxy S4, Galaxy Note II, Galaxy Note 3, etc).

If anyone's interested, I have completed a first version of the OtherCoin app (both the smartcard applet and an Android demo app).

The Android demo app can access 3 types of smartcards - a microSD internal card, a Bluetooth-based smartcard reader (namely this one: https://www.certgate.com/products/cgtoken/) and an NFC card (tested on the Yubikey Neo).

As mentioned in the whitepaper, private keys are generated by adding together two halves - one generated by the card and another one generated by the smartphone. This way the OtherCoin card never has access to your private key but can still guarantee the security of the system by keeping its half private.

The Android app can add new keys (that is ask the smartcard to generate them), request a BTC transfer (ask the card to send its signed public identity that the other card can verify to make sure it's talking to a legit card) and scan a response from the other smartphone (that contains the encrypted Bitcoin private key to import). It uses QR codes for the communication but it could be adapted to use Bluetooth, WiFi or just about anything else.

I've modified the protocol a bit to use ECDH key exchanges instead of RSA (that is the two parties now negotiate a symmetric encryption key using their EC public identities and use that to transfer the Bitcoin private key). RSA was just way too slow and keys were too large to fit into a decent (=readable) QR code.

Finally, it integrates with the Android Bitcoin Wallet to add funds to a specific OtherCoin key (it starts the Bitcoin Wallet with a prefilled destination address - you can see this in the demo movie at around 1:03) and to reveal a key (that is remove from the card and import it into the Bitcoin Wallet for use on the blockchain - see the demo movie at 0:35).

The video is at http://youtu.be/YXGOGMnRx2Y , it probably needs some annotations here and there, I will add them in the coming days.

Feel free to comment and ask questions. The Android app will be open-source to show you how to interact with an OtherCoin card (either via microSD, Bluetooth or NFC) and we're going to need some testers soon. The app is fully functional, everything described in the whitepaper is there and appears to be working fine.

What you're describing there sounds more like the Trezor. The OtherCoin is strictly an offline / off-chain payment solution, it is intentionally not capable of signing transactions or dealing with Bitcoin addresses in any way. It just secures a private key and either releases it to the wallet or securely passes it on to another card. The whitepaper at http://www.othercoin.com/OtherCoin.pdf describes it in more detail, it's definitely not a wallet or a way to sign Bitcoin transactions, it has a different purpose.

Well, the form factor is an SD card and there are drivers for it in both Windows and Linux - you plug the microSD card into a standard microSD reader and it also shows up as a smartcard reader with a smartcard permanently inserted into it. So you can use any of the existing PC/SC libraries to talk to it. My initial target is Android smartphones but the protocol itself will be open, so anyone could implement an interface to the OtherCoin card, on any platform.

It's coming along nicely, still trying to get some seed funding for it but that hasn't stopped development. The protocol has been refined a bit, I will update the PDF description as soon as it stabilizes. I should have an early test version in January if anyone wants to give it a try.