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Author Topic: Smartphones & Bitcoin  (Read 5527 times)
davout
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April 20, 2012, 02:26:14 PM
 #41

you forgot to mention Electrum: http://ecdsa.org/electrum/android.html
transactions are signed on the device, but you do not need to do any backups, because it is a deterministic wallet.
in addition, if they use the same seed, the wallet on your android phone is automatically synchronized with your desktop wallet.

more info here: https://bitcointalk.org/index.php?topic=75617.0;topicseen
You're right! Sorry about that!

I personnaly am not a big fan of limiting one's wallet entropy to a single seed, but I'll admit that it's a very clever idea!

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Phinnaeus Gage
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April 20, 2012, 05:45:14 PM
 #42

Are you saying that the whole blockchain is then stored on the phone as an app?
The blockchain gets recorded in a per-app storage space which is IMO sub-optimal.

This leaves three types of possible wallets :
 - full bitcoin node like BitPak (requires lots of storage, lots of connectivity, IMO a bad option)
 - key-storage on the device like blockchain.info (good option if you're serious about backups and know what you're doing)
 - hosted wallet like Paytunia (in beta), FriendlyPay (good option if you want to take advantage of automatic backups and cold-storage, spend limits, push notifications, automatic green address sends, much better integration into exchanges etc.)

I don't think that any of the two last approaches is inherently better than the other, they just address different use-cases and targets. I think blockchain.info is preferable for advanced or technically literate users who don't mind taking care of their own security, while the hosted wallet approach better addresses everyday payments use cases and regular users. Both approaches are best suited for moderate amounts IMO.

What if smartphones were pre-installed with the blockchain, then automatically updated when the phone is on?

~Bruno~
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April 20, 2012, 09:01:19 PM
 #43

What if smartphones were pre-installed with the blockchain, then automatically updated when the phone is on?
How would that change anything? (or maybe you're being sarcastic Cheesy)

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April 20, 2012, 09:14:28 PM
 #44

What if smartphones were pre-installed with the blockchain, then automatically updated when the phone is on?
How would that change anything? (or maybe you're being sarcastic Cheesy)

I was serious, though my wording could have been better.

I simply envisioned (a) smartphones to have the blockchain pre-installed prior to purchasing them. I was wondering how practical this would be, and its feasibility in the future.

~Bruno~
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April 21, 2012, 07:33:49 AM
 #45

I personnaly am not a big fan of limiting one's wallet entropy to a single seed

huh??? using multiple seeds because you believe that a single seed does not give you sufficient protection is a terrible idea.

the only thing that matters is how much bits of entropy protects your money. if you believe that your seed/private key/password/whatever is not long enough, the correct strategy is to use a longer one, not to split your assets in order to limit damage.

FYI, Electrum default seeds have 128 bits of entropy, and standard Bitcoin addresses have 160 bits of entropy.


Electrum: the convenience of a web wallet, without the risks
davout
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April 22, 2012, 02:42:02 PM
 #46

I simply envisioned (a) smartphones to have the blockchain pre-installed prior to purchasing them. I was wondering how practical this would be, and its feasibility in the future.
I'm not sure it would be very practical for manufacturers (they'd have to update the chain constantly), for users (they'd have to give up significant storage space), and for cellular networks.

huh??? using multiple seeds because you believe that a single seed does not give you sufficient protection is a terrible idea.

the only thing that matters is how much bits of entropy protects your money. if you believe that your seed/private key/password/whatever is not long enough, the correct strategy is to use a longer one, not to split your assets in order to limit damage.

FYI, Electrum default seeds have 128 bits of entropy, and standard Bitcoin addresses have 160 bits of entropy.
I never said it would be a good idea to use multiple seeds.
I'm simply stating that using a seed to deterministically generate an potentially infinite sequence of adresses is not neutral from a security POV since you're basically limiting the entropy of your complete key collection to the entropy of the original seed. Which according to you is (by default) even lower than the entropy provided by the random generation of a single address.

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April 22, 2012, 08:11:56 PM
 #47

I never said it would be a good idea to use multiple seeds.
I'm simply stating that using a seed to deterministically generate an potentially infinite sequence of adresses is not neutral from a security POV since you're basically limiting the entropy of your complete key collection to the entropy of the original seed. Which according to you is (by default) even lower than the entropy provided by the random generation of a single address.

I believe that a 128 bits seed is safe given today's technology. However, I am not an expert cryptographer; I formed this belief from discussions with Bitcoin developers. If you think that 128 bits is not sufficient please let me know.

However, if you believe that the seed is long enough to be safe, then there is absolutely no reason to increase the entropy of your wallet by using random keys. I suppose that you have read a very different argument, about the fact that a wallet using random keys is "permanently unstolen", and that you are somehow confusing that argument with the entropy of a wallet. That argument is about an attacker gaining access to an old version of your wallet, and it has nothing to do with entropy.

Electrum: the convenience of a web wallet, without the risks
davout
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April 22, 2012, 10:24:41 PM
 #48

I believe that a 128 bits seed is safe given today's technology. However, I am not an expert cryptographer; I formed this belief from discussions with Bitcoin developers. If you think that 128 bits is not sufficient please let me know.
I just did the math. Looks like it is ridiculously safe.

Time in billions of years it would take to exhaust seed space at 1 billion seeds/second --> http://tinyurl.com/6uy9acm

It is safer than it intuitively looks like I guess Smiley

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April 23, 2012, 01:43:34 PM
 #49

If you get an Android phone, I would recommend you use "Bitcoin Wallet" app by Andreas Schildbach. Do NOT use the app by Bitcoin Labs - it has serious issues with bitcoins that appear to be sent but are actually not.

Do not waste your time debating whether Bitcoin can work. It does work.

"Early adopters will profit" is not a sufficient condition to classify something as a pyramid or Ponzi scheme. If it was, Apple and Microsoft stock are Ponzi schemes.

There is no such thing as "market manipulation." There is only buying and selling.
davout
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April 23, 2012, 01:51:24 PM
 #50

If you get an Android phone, I would recommend you use "Bitcoin Wallet" app by Andreas Schildbach. Do NOT use the app by Bitcoin Labs - it has serious issues with bitcoins that appear to be sent but are actually not.
There's also Paytunia that does good job if you don't want to download the full chain and don't mind using a hosted wallet.

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e-ducat.fr


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April 27, 2012, 12:34:52 PM
 #51

If you get an Android phone, I would recommend you use "Bitcoin Wallet" app by Andreas Schildbach.
I would not recommend it to newbies, because most people would not know how to backup their key from a mobile phone.
Should anything happen to the mobile device or app, the bitcoins are lost.

In contrast a true "light" client like Paytunia is a safer option: if the device is lost, the coins are safely stored and recovered from the server.

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May 04, 2012, 12:58:58 PM
 #52

First off, thanks to everybody who helped in my decision making. I've decided to take French for two semesters.  Grin

Seriously, I purchased the Samsung Galaxy SII Titanium with T-Mobile. Not sure if I made the correct choice, for it took over eight hours to get the phone activate--SERIOUSLY! The first three hours, I tried to do it on my own. No joy! I couldn't get pass the Google sign in/up stage. Then I went on live and chatted with a rep on the Samsung site. She finally told me that she couldn't help me and that I needed to contact T-Mobile, of which there office closes at 10PM. So I went to chat with a T-Mobile rep online. After about a half hour, she couldn't help me either, but was kind enough to give me a phone number to call. The same number I already had at my disposal but it was after 10PM. I tried it anyway. Guess what? I got lucky and was able to get a live rep, for she was on the West Coast. (Yes, all three support individuals were women and spoke English and, yes, at one point I thought I was being scammed because of this fact.  Roll Eyes) After being on the phone with the T-Mobile girl for over an hour, she finally said that there was nothing she could do, but offered up one finally solution. She told be go outside and see if I can get better reception. So, with a phone in each hand, I went to the door to open it, but my hands were full. Fortunately, I dropped the $500 Samsung smartphone, freeing up one hand to open the door. I opened the door, then picked the now dented phone and the battery that fell out of the back, as well as the back cover. On instinct, I placed the battery back into the phone and, guess what? The phone started working. She kindly informed me that that's what we should have done first--take out, then re-install the battery.

Now, I'm a proud owner of a dented smartphone that has a screen that no longer rotates when I rotate the phone. And it's all Bitcoin's fault. Therefore, I'm going sue Bitcoin for all my hard-aches.  Wink

C'est la vie!

~Bruno~
P4man
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May 05, 2012, 02:33:17 PM
 #53

I would not recommend it to newbies, because most people would not know how to backup their key from a mobile phone.
Should anything happen to the mobile device or app, the bitcoins are lost.

If you use blockchain app, it uses the same wallet as the online one, so its already backed up in the cloud, and from the site, you can easily email an ecrypted backup to yourself.

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May 05, 2012, 07:03:40 PM
 #54

Phinnaeus it's not our fault if you buy the phone with T Mobile Cheesy

What about the next time you just buy the phone? Like you go to the shop, you say "i want to buy this", you pay and that's all? What i don't understand is why in USA people just don't buy the phone and then just put in their card
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May 05, 2012, 09:10:32 PM
 #55

What about the next time you just buy the phone? Like you go to the shop, you say "i want to buy this", you pay and that's all? What i don't understand is why in USA people just don't buy the phone and then just put in their card
That's rarely an option, because many phones are subsidized by the carrier. And, the carrier locks the phone to their network, making it impossible to switch. You could buy an unlocked phone from some places, but they cost a lot more.

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May 05, 2012, 09:22:23 PM
 #56

First off, thanks to everybody who helped in my decision making. I've decided to take French for two semesters.  Grin

Seriously, I purchased the Samsung Galaxy SII Titanium with T-Mobile. Not sure if I made the correct choice, for it took over eight hours to get the phone activate--SERIOUSLY! The first three hours, I tried to do it on my own. No joy! I couldn't get pass the Google sign in/up stage. Then I went on live and chatted with a rep on the Samsung site. She finally told me that she couldn't help me and that I needed to contact T-Mobile, of which there office closes at 10PM. So I went to chat with a T-Mobile rep online. After about a half hour, she couldn't help me either, but was kind enough to give me a phone number to call. The same number I already had at my disposal but it was after 10PM. I tried it anyway. Guess what? I got lucky and was able to get a live rep, for she was on the West Coast. (Yes, all three support individuals were women and spoke English and, yes, at one point I thought I was being scammed because of this fact.  Roll Eyes) After being on the phone with the T-Mobile girl for over an hour, she finally said that there was nothing she could do, but offered up one finally solution. She told be go outside and see if I can get better reception. So, with a phone in each hand, I went to the door to open it, but my hands were full. Fortunately, I dropped the $500 Samsung smartphone, freeing up one hand to open the door. I opened the door, then picked the now dented phone and the battery that fell out of the back, as well as the back cover. On instinct, I placed the battery back into the phone and, guess what? The phone started working. She kindly informed me that that's what we should have done first--take out, then re-install the battery.

Now, I'm a proud owner of a dented smartphone that has a screen that no longer rotates when I rotate the phone. And it's all Bitcoin's fault. Therefore, I'm going sue Bitcoin for all my hard-aches.  Wink

C'est la vie!

~Bruno~


Did I recommend the Samsung s2? I´m sorry I mixed it up. This is the phone you should have gotten Wink
http://www.youtube.com/watch?v=pwIVf2nqJsg

I´m sorry to hear but you should be lucky you got the Samsung. The iphones are made of glass, they break if you look at them to long.
I went to three different stores, they all told me that they got back Iphones that where broken from falls but Samsung was one of the best at taking hits.

Samsung s2 vs iphone 4 droptest:
http://www.youtube.com/watch?v=tKJp9EMRjXY

You can check if the gyro is broken by dialing *#0*# this will take you to a "hidden" test menu.

Bitcoins - Because we should not pay to use our money
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May 06, 2012, 05:34:09 PM
 #57

What about the next time you just buy the phone? Like you go to the shop, you say "i want to buy this", you pay and that's all? What i don't understand is why in USA people just don't buy the phone and then just put in their card
That's rarely an option, because many phones are subsidized by the carrier. And, the carrier locks the phone to their network, making it impossible to switch. You could buy an unlocked phone from some places, but they cost a lot moreless.

Fixed that for you.

Subsidised phones, when you consider the amount you pay over the contract period, are considerably more expensive.  If you've got cashflow problems, then perhaps its better for you to pay for it over 18 months; but everyone else would be better off paying the up front price for an unlocked phone, then negotiating an amazing deal from the carrier.  Which isn't hard to do at all.


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June 05, 2012, 10:15:33 AM
 #58

I bricked my LG optimus trying to upgrade it to android 4, so I looked for a cheapish replacement and found this:
http://www.aliexpress.com/store/803232/211505324-557211424/Titan-X310e-Android-4-0-ICS-4-3-inch-Phone-MTK6575-1GHz-CPU-512MB-RAM-4GB.html

I actually ordered it on ebay for GBP 154,99.

Its a chinese no name phone, fake HTC I guess, under the hood its the same phone as the zopo ZP100;  specs look pretty damn decent and plenty good for me (1GH single core Cortex A9, high res screen, dual sim, dual camera etc), and Ive seen a few user reviews that all say its actually a fantastic phone except for rather poor GPS reception. I can live with that given the price is only a fraction of an otherwise more or less comparable galaxy S2. Its actually cheaper than most second hand Galaxy S1s Ive seen.

Here is a youtube clip of the phone in action:

http://www.youtube.com/watch?v=Hax0HkHxpYA&feature=related

Thought Id let you know in case someone is looking for a mid range 4.3" android phone and doesnt want to spend more on it than on a second hand car Smiley.

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June 05, 2012, 02:49:41 PM
 #59

I recommend going into a CEX or cash converters (in the UK) and picking up a "new" phone there. people with contracts go and drop brand new models in for next to nothing. they then sell.

I got a Motorola XT910 for 279GBP. Its flawless, headphones werent even opened.
DeathAndTaxes
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June 05, 2012, 03:55:05 PM
 #60

Subsidised phones, when you consider the amount you pay over the contract period, are considerably more expensive.  If you've got cashflow problems, then perhaps its better for you to pay for it over 18 months; but everyone else would be better off paying the up front price for an unlocked phone, then negotiating an amazing deal from the carrier.  Which isn't hard to do at all.

Exactly and prepaid is growing up.  

Unlocked Samsung Galaxy Nexus (from Google) - $400
$35 per month prepaid plan from T-Mobile  (granted this plan only has 100 voice minutes but there are other options)
3% discount from Tangible Cryptography for paying with Bitcoins.
2 years of service & hardware = $400 + 0.97*35*24 = $1214
Saying good bye to contacts forever.  Priceless.

Now compare that to what a "low cost" top of the line Android phone w/ locked in contract is going to cost you. Smiley
Remember that "$60" plan is more like $75 to $80 when you include all the fees, taxes, service charges, 9/11, USF, etc.  
$35 (or $45 or $60) prepaid plan already includes all taxes & fees.
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