Bitcoin Wiki - User contributions [en]

Smart card wallet

2013-01-07T02:39:45Z

Dwhite: /* 3. implement wallet on a simple smart card */

This pages gathers resources for the implementation of a Bitcoin wallet on a smart card.

===Rationale===

*Computers and smartphones are target for malware. The software on a smart card can be protected.
*Smart cards do not need a battery, nor internet connection, they are robust.
*Adoption: people are already used to paying with smart cards.

===Desired features===

*no blockchain, no node; the card contains only private keys, and an algorithm to sign a transaction
*the smart card should have its own keyboard (for pin code protection) and display (to show the transaction amount)
(<- Alternative to this is the card returning, to the terminal screen, the debit amount multiplied by a number only the card holder knows which cycles from 1 to 100 to 1 incrementing by 1 each transfer - the card is locked 10 minutes if a second amount is send before a pin is typed.)
* The card holder will know pin, puk, private key and address only from when he programmed it or ordered his smart card.
*the card should implement a deterministic wallet, so that funds can be recovered if the card is lost.

===Usage scenario===

* the reading device may belong to a merchant at a point of sale; it cannot be trusted with private keys.
* the reading device is connected to a full bitcoin node; it can be trusted for getting and sending blockchain information.
* the reading device sends to the card the current balance of its bitcoin addresses. This information can be cached in the card.
* the reading device sends a bitcoin receiving address and transaction amount to the card.
* the amount is displayed by the card ; the user confirms the transaction with his pin code.
* the smart card creates a signed transaction and sends it to the reading device
* the transaction is checked and broadcast by the bitcoin node.

==Implementation steps==

===1. write a bitcoin daemon that can talk to a lightweight wallet===
*this has been done already, see for example bitcoinjs: https://github.com/bitcoinjs/bitcoinjs-lib
*See also this pull request: [https://github.com/piotrnar/bitcoin/tree/importexporttx importexporttx] can be used to broadcast the transaction
* https://bitcointalk.org/index.php?topic=28278.msg383312#msg383312

===2. write a lightweight wallet===
*wallet without blockchain, in order to test the daemon
*this lightweight wallet will be later implemented on the card
*use it to define the communication protocol between card and reading device.

update: this is done, see [[Electrum]]

===3. implement wallet on a simple smart card===

* http://www.opensc-project.org/opensc openSC : tools and libraries for smart cards.
* amadousarr.free.fr/crypto/ECDSAJAVACARD.pdf : A Software Implementation of ECDSA on a Java Smart Card
* http://www.acs.com.hk : cards, readers, development kits; no display, pincode needs to be typed on the reading device
* http://www.basiccard.com/index.html?overview.htm : Smart Card (ZC7.5) which contains RSA/EC and DES/AES coprocessors. Used in an implementation of the OpenPGP Card 2.0 standard (http://g10code.com/p-card.html)

===4. implement wallet on a smart card with display and pincode ===

list of vendors:
* http://www.nidsecurity.com/products/solution-enterprise.html (smart cards with LCD displays)
* http://www.avesodisplays.com/ (smard cards with flexible displays)

==references==
*https://bitcointalk.org/index.php?topic=7539.0 Bitcoin smartcard Point of Sale terminal
*https://bitcointalk.org/index.php?topic=20933.0 Bitcoin and Smart Cards

[[category:Developer]]
[[category:Technical]]
[[category:Wallets]]
[[Category:Mobile]]

Smart card wallet

2013-01-07T01:46:03Z

Dwhite: /* 3. implement wallet on a simple smart card */

This pages gathers resources for the implementation of a Bitcoin wallet on a smart card.

===Rationale===

*Computers and smartphones are target for malware. The software on a smart card can be protected.
*Smart cards do not need a battery, nor internet connection, they are robust.
*Adoption: people are already used to paying with smart cards.

===Desired features===

*no blockchain, no node; the card contains only private keys, and an algorithm to sign a transaction
*the smart card should have its own keyboard (for pin code protection) and display (to show the transaction amount)
(<- Alternative to this is the card returning, to the terminal screen, the debit amount multiplied by a number only the card holder knows which cycles from 1 to 100 to 1 incrementing by 1 each transfer - the card is locked 10 minutes if a second amount is send before a pin is typed.)
* The card holder will know pin, puk, private key and address only from when he programmed it or ordered his smart card.
*the card should implement a deterministic wallet, so that funds can be recovered if the card is lost.

===Usage scenario===

* the reading device may belong to a merchant at a point of sale; it cannot be trusted with private keys.
* the reading device is connected to a full bitcoin node; it can be trusted for getting and sending blockchain information.
* the reading device sends to the card the current balance of its bitcoin addresses. This information can be cached in the card.
* the reading device sends a bitcoin receiving address and transaction amount to the card.
* the amount is displayed by the card ; the user confirms the transaction with his pin code.
* the smart card creates a signed transaction and sends it to the reading device
* the transaction is checked and broadcast by the bitcoin node.

==Implementation steps==

===1. write a bitcoin daemon that can talk to a lightweight wallet===
*this has been done already, see for example bitcoinjs: https://github.com/bitcoinjs/bitcoinjs-lib
*See also this pull request: [https://github.com/piotrnar/bitcoin/tree/importexporttx importexporttx] can be used to broadcast the transaction
* https://bitcointalk.org/index.php?topic=28278.msg383312#msg383312

===2. write a lightweight wallet===
*wallet without blockchain, in order to test the daemon
*this lightweight wallet will be later implemented on the card
*use it to define the communication protocol between card and reading device.

update: this is done, see [[Electrum]]

===3. implement wallet on a simple smart card===

* http://www.opensc-project.org/opensc openSC : tools and libraries for smart cards.
* amadousarr.free.fr/crypto/ECDSAJAVACARD.pdf : A Software Implementation of ECDSA on a Java Smart Card
* http://www.acs.com.hk : cards, readers, development kits; no display, pincode needs to be typed on the reading device
* http://www.basiccard.com/index.html?overview.htm : Smart Card (ZC7.5) which contains RSA/EC and DES/AES coprocessors. Used in the implementation of the OpenPGP Card 2.0 standard (http://g10code.com/p-card.html)

===4. implement wallet on a smart card with display and pincode ===

list of vendors:
* http://www.nidsecurity.com/products/solution-enterprise.html (smart cards with LCD displays)
* http://www.avesodisplays.com/ (smard cards with flexible displays)

==references==
*https://bitcointalk.org/index.php?topic=7539.0 Bitcoin smartcard Point of Sale terminal
*https://bitcointalk.org/index.php?topic=20933.0 Bitcoin and Smart Cards

[[category:Developer]]
[[category:Technical]]
[[category:Wallets]]
[[Category:Mobile]]