This application describes the APDU messages interface to communicate with the æternity application.
The application covers the following functionalities :
-
Retrieve a æternity address given an account number
-
Sign a spend æternity transaction given an account number
-
Sign a message given an account number
The application interface can be accessed over HID or BLE
This command returns æternity address for the given account number
The address can be optionally checked on the device before being returned.
This command signs an æternity transaction after having the user validate the following parameters
-
Fees
-
Recipient address
-
Amount
The input data is the RLP encoded spend transaction (https://github.com/aeternity/protocol/blob/master/serializations.md#spend-transaction), streamed to the device in 255 bytes maximum data chunks.
This command signs an æternity message following the signPersonalMessage (https://github.com/aeternity/aepp-sdk-js/blob/4936bb0b08bf43f6283de564785ae3b46e6d0c8d/es/utils/crypto.js#L259).
The input data is the message to sign, streamed to the device in 255 bytes maximum data chunks
Command
CLA |
INS |
P1 |
P2 |
Lc |
Le |
E0 |
08 |
00 : first message data block 80 : subsequent message data block |
00 |
variable |
variable |
Input data (first message data block)
Description |
Length |
An account number to retrieve |
4 |
Full message length |
4 |
Message chunk |
variable |
Input data (other transaction data block)
Description |
Length |
Message chunk |
variable |
Output data
Description |
Length |
signature |
64 |
Ledger APDUs requests and responses are encapsulated using a flexible protocol allowing to fragment large payloads over different underlying transport mechanisms.
The common transport header is defined as follows :
Description |
Length |
Communication channel ID (big endian) |
2 |
Command tag |
1 |
Packet sequence index (big endian) |
2 |
Payload |
var |
The Communication channel ID allows commands multiplexing over the same physical link. It is not used for the time being, and should be set to 0101 to avoid compatibility issues with implementations ignoring a leading 00 byte.
The Command tag describes the message content. Use TAG_APDU (0x05) for standard APDU payloads, or TAG_PING (0x02) for a simple link test.
The Packet sequence index describes the current sequence for fragmented payloads. The first fragment index is 0x00.
APDU Command payloads are encoded as follows :
Description |
Length |
APDU length (big endian) |
2 |
APDU CLA |
1 |
APDU INS |
1 |
APDU P1 |
1 |
APDU P2 |
1 |
APDU length |
1 |
Optional APDU data |
var |
APDU payload is encoded according to the APDU case
Case Number |
Lc |
Le |
Case description |
1 |
0 |
0 |
No data in either direction - L is set to 00 |
2 |
0 |
!0 |
Input Data present, no Output Data - L is set to Lc |
3 |
!0 |
0 |
Output Data present, no Input Data - L is set to Le |
4 |
!0 |
!0 |
Both Input and Output Data are present - L is set to Lc |
APDU Response payloads are encoded as follows :
Description |
Length |
APDU response length (big endian) |
2 |
APDU response data and Status Word |
var |
Messages are exchanged with the dongle over HID endpoints over interrupt transfers, with each chunk being 64 bytes long. The HID Report ID is ignored.
A similar encoding is used over BLE, without the Communication channel ID.
The application acts as a GATT server defining service UUID D973F2E0-B19E-11E2-9E96-0800200C9A66
When using this service, the client sends requests to the characteristic D973F2E2-B19E-11E2-9E96-0800200C9A66, and gets notified on the characteristic D973F2E1-B19E-11E2-9E96-0800200C9A66 after registering for it.
Requests are encoded using the standard BLE 20 bytes MTU size
The following standard Status Words are returned for all APDUs - some specific Status Words can be used for specific commands and are mentioned in the command description.
Status Words
SW |
Description |
6700 |
Incorrect length |
6982 |
Security status not satisfied (Canceled by user) |
6A80 |
Invalid data |
6B00 |
Incorrect parameter P1 or P2 |
6Fxx |
Technical problem (Internal error, please report) |
9000 |
Normal ending of the command |