rfc/content/docs/rfcs/63

slug	title	name	status	category	description	editor	contributors
63	63/STATUS-Keycard-Usage	Status Keycard Usage	raw	Standards Track	Describes how an application can use the Status Keycard to create, store and transact with different account addresses.	Aaryamann Challani <aaryamann@status.im>	Jimmy Debe <jimmy@status.im>

Terminology

• Account: A valid BIP-32 compliant key.
• Multiaccount: An account from which multiple Accounts can be derived.

Abstract

This specification describes how an application can use the Status Keycard to -

1. Create Multiaccounts
2. Store Multiaccounts
3. Use Multiaccounts for transaction or message signing
4. Derive Accounts from Multiaccounts

More documentation on the Status Keycard can be found here

Motivation

The Status Keycard is a hardware wallet that can be used to store and sign transactions. For the purpose of the Status App, this specification describes how the Keycard SHOULD be used to store and sign transactions.

Usage

Endpoints

1. Initialize Keycard (/init-keycard)

To initialize the keycard for use with the application. The keycard is locked with a 6 digit pin.

Request wire format

{
  "pin": 6_digit_pin
}

Response wire format

{
  "password": password_to_unlock_keycard,
  "puk": 12_digit_recovery_code,
  "pin": provided_pin,
}

The keycard MUST be initialized before it can be used with the application. The application SHOULD provide a way to recover the keycard in case the pin is forgotten.

2. Get Application Info (/get-application-info)

To fetch if the keycard is ready to be used by the application.

Request wire format

The requester MAY add a pairing field to filter through the generated keys

{
  "pairing": <shared_secret>/<pairing_index>/<256_bit_salt> OR null
}

Response wire format

If the keycard is not initialized yet

{
  "initialized?": false
}

If the keycard is initialized

{
  "free-pairing-slots": number, 
  "app-version": major_version.minor_version, 
  "secure-channel-pub-key": valid_bip32_key,, 
  "key-uid": unique_id_of_the_default_key,
  "instance-uid": unique_instance_id, 
  "paired?": bool,
  "has-master-key?": bool, 
  "initialized?" true
}

3. Pairing the Keycard to the Client device (/pair)

To establish a secure communication channel described here, the keycard and the client device need to be paired.

Request wire format

{
  "password": password_to_unlock_keycard
}

Response wire format

"<shared_secret>/<pairing_index>/<256_bit_salt>"

4. Generate a new set of keys (/generate-and-load-keys)

To generate a new set of keys and load them onto the keycard.

Request wire format

{
  "mnemonic": 12_word_mnemonic,
  "pairing": <shared_secret>/<pairing_index>/<256_bit_salt>,
  "pin": 6_digit_pin
}

Response wire format

{
  "whisper-address": 20_byte_whisper_compatible_address, 
  "whisper-private-key": whisper_private_key, 
  "wallet-root-public-key": 256_bit_wallet_root_public_key, 
  "encryption-public-key": 256_bit_encryption_public_key,, 
  "wallet-root-address": 20_byte_wallet_root_address, 
  "whisper-public-key": 256_bit_whisper_public_key,
  "address": 20_byte_address, 
  "wallet-address": 20_byte_wallet_address,, 
  "key-uid": 64_byte_unique_key_id, 
  "wallet-public-key": 256_bit_wallet_public_key,
  "public-key": 256_bit_public_key,
  "instance-uid": 32_byte_unique_instance_id,
}

5. Get a set of generated keys (/get-keys)

To fetch the keys that are currently loaded on the keycard.

Request wire format

{
  "pairing": <shared_secret>/<pairing_index>/<256_bit_salt>,
  "pin": 6_digit_pin
}

Response wire format

{
  "whisper-address": 20_byte_whisper_compatible_address, 
  "whisper-private-key": whisper_private_key, 
  "wallet-root-public-key": 256_bit_wallet_root_public_key, 
  "encryption-public-key": 256_bit_encryption_public_key,
  "wallet-root-address": 20_byte_wallet_root_address, 
  "whisper-public-key": 256_bit_whisper_public_key,
  "address": 20_byte_address, 
  "wallet-address": 20_byte_wallet_address, 
  "key-uid": 64_byte_unique_key_id, 
  "wallet-public-key": 256_bit_wallet_public_key,
  "public-key": 256_bit_public_key,
  "instance-uid": 32_byte_unique_instance_id,
}

6. Sign a transaction (/sign)

To sign a transaction using the keycard, passing in the pairing information and the transaction to be signed.

Request wire format

{
  "hash": 64_byte_hash_of_the_transaction,
  "pairing": <shared_secret>/<pairing_index>/<256_bit_salt>,
  "pin": 6_digit_pin,
  "path": bip32_path_to_the_key
}

Response wire format

<256_bit_signature>

7. Export a key (/export-key)

To export a key from the keycard, passing in the pairing information and the path to the key to be exported.

Request wire format

{
  "pairing": <shared_secret>/<pairing_index>/<256_bit_salt>,
  "pin": 6_digit_pin,
  "path": bip32_path_to_the_key
}

Response wire format

<256_bit_public_key>

8. Verify a pin (/verify-pin)

To verify the pin of the keycard.

Request wire format

{
  "pin": 6_digit_pin
}

Response wire format

1_digit_status_code

Status code reference:

• 3: PIN is valid

9. Change the pin (/change-pin)

To change the pin of the keycard.

Request wire format

{
  "new-pin": 6_digit_new_pin,
  "current-pin": 6_digit_new_pin,
  "pairing": <shared_secret>/<pairing_index>/<256_bit_salt>
}

Response wire format

If the operation was successful

true

If the operation was unsuccessful

false

10. Unblock the keycard (/unblock-pin)

If the Keycard is blocked due to too many incorrect pin attempts, it can be unblocked using the PUK.

Request wire format

{
  "puk": 12_digit_recovery_code,
  "new-pin": 6_digit_new_pin,
  "pairing": <shared_secret>/<pairing_index>/<256_bit_salt>
}

Response wire format

If the operation was successful

true

If the operation was unsuccessful

false

Flows

Any application that uses the Status Keycard MAY implement the following flows according to the actions listed above.

1. A new user wants to use the Keycard with the application

1. The user initializes the Keycard using the /init-keycard endpoint.
2. The user pairs the Keycard with the client device using the /pair endpoint.
3. The user generates a new set of keys using the /generate-and-load-keys endpoint.
4. The user can now use the Keycard to sign transactions using the /sign endpoint.

2. An existing user wants to use the Keycard with the application

1. The user pairs the Keycard with the client device using the /pair endpoint.
2. The user can now use the Keycard to sign transactions using the /sign endpoint.

3. An existing user wants to use the Keycard with a new client device

1. The user pairs the Keycard with the new client device using the /pair endpoint.
2. The user can now use the Keycard to sign transactions using the /sign endpoint.

4. An existing user wishes to verify the pin of the Keycard

1. The user verifies the pin of the Keycard using the /verify-pin endpoint.

5. An existing user wishes to change the pin of the Keycard

1. The user changes the pin of the Keycard using the /change-pin endpoint.

6. An existing user wishes to unblock the Keycard

1. The user unblocks the Keycard using the /unblock-pin endpoint.

Security Considerations

Inherits the security considerations of Status Keycard

Privacy Considerations

Inherits the privacy considerations of Status Keycard

Copyright

Copyright and related rights waived via CC0.

References

1. BIP-32 specification
2. Keycard documentation
3. 16/Keycard-Usage