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Author Topic: Today my Bit-Card (paper wallet) arrived and it looks pretty awesome..  (Read 1319 times)
Grinny
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November 21, 2013, 06:49:22 PM
 #1

Hey folks,

just wanted to show you some pictures of my brand new Bit-Card I ordered two days ago at http://bit-card.com/
I really like the design of the card, especially the hologram that shows several different styles of our beloved BTC logo, framed by typical bitcoin slogans.
The card came with a nice sticker (see last image) that I'm definitely going to put on a prominent place Grin

Quick Review:

Pros:
- Really neat designs to choose from
- You can label your card (mine says "Rentenkasse" - german for "pension fund")
- Hassle-free ordering via webstore
- Fast shipping (within germany)
- Private Key can be secured by BIP 0038 via i.e. http://www.bit2factor.org/
- support: my questions were answered within half a day
- Price: 0.008 BTC

Cons:
- QR-Codes don't work properly with older iOS Cams (like the one in my iPhone 4S)
- Confirmation code & BTC address are shown only on the card / import to external wallet by copy&paste not possible (for securtiy reasons, which is good, but annoying)
- Procedure to encrypt your private key is not newbie friendly

Front:


Back:


Sticker:

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dominicwin
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November 21, 2013, 06:52:51 PM
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Love it, even if the slogan is slightly ominous

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sveetsnelda
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November 21, 2013, 06:54:34 PM
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These look *very* cool and very well-made.  Someone put a lot of thought into these.

However, I still have a hard time trusting someone to not jot down my private key during manufacturing.  :-/

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trout
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November 21, 2013, 07:08:43 PM
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However, I still have a hard time trusting someone to not jot down my private key during manufacturing.  :-/
apparently, they can't. That's what BIP0038 is for.
I've also found out about it from this thread, reading.

Barek
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November 21, 2013, 07:30:31 PM
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It looks great, but I don't understand how it works, yet.

If the key on it is encrypted, why does it need holograms and such? This is for looks only?

Wouldn't you need to break the hologram to get to the key? Don't you need to verify the key was printed correctly before you transfer funds to the address? Would be bad to find out there was a manufacturing error a couple years down the line.
sveetsnelda
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November 21, 2013, 07:47:57 PM
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However, I still have a hard time trusting someone to not jot down my private key during manufacturing.  :-/
apparently, they can't. That's what BIP0038 is for.
I've also found out about it from this thread, reading.

Beautiful...   I missed that in the OP.  I'll be looking into these.   Smiley

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Grinny
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November 21, 2013, 07:53:09 PM
 #7

It looks great, but I don't understand how it works, yet.

If the key on it is encrypted, why does it need holograms and such? This is for looks only?

Wouldn't you need to break the hologram to get to the key? Don't you need to verify the key was printed correctly before you transfer funds to the address? Would be bad to find out there was a manufacturing error a couple years down the line.

Well, the hologram protects your private key. Of course this is only a small additional security layer for those cards that are encrypted by bip 0038, but anyway, as long as the hologram is intact, you know that noone tried to manipulate your card.

How (i think) it works (BIP0038 encrypted version):

- result: you want to encrypt your private wallet key
- therefore you choose a passphrase
- you won't send bit-card your passphrase, instead of you generate an intermediate key by using http://www.bit2factor.org/
- this intermediate key will be send to bit-card
- with your intermediate key, bit-card is able to generate an encrypted private wallet key without beeing able to decrypt or even see it
- your private encrypted wallet key is generated and secured by the hologram, in addition they will print a confirmation key on your card

- with your original passphrase (that you didn't provide to anyone), your confirmation key (written on the front of the card), the encrypted private key (secured by the hologram) AND your public BTC address, you can decrypt your private wallet key and withdraw your coins, voilà!

Btw. this is the same procedure as used by Casascius for his Coins.

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jeppe
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November 21, 2013, 08:20:00 PM
 #8

Looks interesting but still dont get how it works :/ I like the design a lot !
Grinny
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November 21, 2013, 08:58:42 PM
 #9

it's an offline paper wallet.
store it in a safe place and deposit money on it by sending btc to your public address stated on the front of your bit-card.
if you want to withdraw money from it, destroy the hologram, generate your private key and import it to the wallet client of your choice.
i'm going to use it as an unaccessible, secure place where i can save my small coins for later (~5 years).

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