QR code mechanism
Scanning QR codes
This section serves to illustrate how wallets can employ the QR code scanning feature to carry out tasks such as login, smart contract invocation, and other services.
There are two parties that are involved in the process:
The
dApp
: Blanket term that representsdApps
developed for the users of Ontology ecosystem.The
Provider
: Wallets that supportdAPI
, and adhere to it's specifications.
Interaction process
A dApp provides a QR code and the user scans it using the wallet. The QR code mechanism currently supports two functions: login and contract invocation.
Login by scanning QR code
The process flow is as follows-
Wallet scans the QR code provided by the
dApp
.Provider
fetches thecallback URL
and the verification message, carries out user authentication and signature, and the transaction is carries out using thedApps
callback address.The
dApp
back end carries out signature verification and returns the result to the wallet.
Invoke smart contract using QR code
The process flow is as follows-
Wallet scans the QR code provided by the
dApp
.Wallet initiates a transaction, the user signs it, the transaction is pre-executed, the user provides confirmation, the information is transmitted on to the chain, and finally the transaction
hash
is returned to thedApp
back end using the callback address provided.dApp
back end uses the transactionhash
to query the successful contract execution and transaction details.
dAPI protocol usage
The following scenarios can be realized by integrating the dAPI -
Login
Authentication is carried out by scanning the QR code from the wallet. The wallet fetches login parameters, carries out signature authorization and sends them to the dApp
back end.
Field | Data type | Description |
action | string | States the function performed by the QR code, Login to be defined as "login" and contract invocation as "invoke" |
id | string | Serial number (optional) |
type | string | Login method used, ONT ID login to be set as "ontid" and wallet address login to be set as "address" |
dappName | string | Name of the dApp |
dappIcon | string | dApp icon resource link |
message | string | Randomly generated message for identity verification |
expire | long | Unix time stamp for when the QR code expires (optional) |
callback | string | Callback URL to communicate with the dApp back end |
dApp back end's return interface
Here's the post method message structure:
Field | Data type | Description |
action | string | Operation type |
id | string | Serial number (optional) |
params | string | Parameters required by the method |
type | string | Login method used, "ontid" if ONT ID is used to login and "address" when the wallet address is used to login |
user | string | Identifier of the account that is used for signature |
message | string | Randomly generated message for identity verification |
publickey | string | Account's public key |
signature | string | Digital signature |
If the transaction was successful, the success message is sent in response.
Otherwise, the failure message is sent in response.
Message Signature
Message signature is essentially the same as login protocol, except that the dApp
name and the icon are not a part of the request that is sent.
The structure of the signature request sent by the dApp
after URI
and Base64
encoding are as follows:
Or when multiple messages are signed:
Field | Data type | Description |
action | string | Operation type |
type | string | Login method used, "ontid" if ONT ID is used to login and "address" when the wallet address is used |
message | string | Randomly generated message for identity verification |
ishex | bool | Whether the message is a hex code |
callback | string | Callback URL to communicate with the dApp back end |
The response that the wallet sends back to the dApp
, after URI
and Base 64
encoding, is structured as follows:
If the action is "multimessage" the response sent back to the dApp
is an array
Contract Invocation
A payment operation also falls under the category of contract invocation, adopting a uniform protocol standard. The standard can be defined as follows:
Field | Data type | Description |
action | string | Operation type, Login to be defined as "login" and contract invocation as "invoke" |
qrcodeUrl | string | Address for QR code parameters |
callback | string | The callback address to send the transaction |
The data obtained from the qrcodeURL
link's GET
method is as follows-
Base58 addresses such as AUr5QUfeBADq6BMY6Tp5yuMsUNGpsD7nLZ
can be assigned to the %address
parameter, and the wallet will automatically assign it as the wallet's asset address. If the parameters contain an %ontid
, the wallet will also automatically assign it to the wallet's ONT ID
address.
The wallet initiates a transaction, the user authenticates and signs it, the transaction is pre-executed, issued, and then the transaction hash
is sent to the callback URL
using POST
method.
The success message has the following structure:
And the failure message is as follows:
Pre-executing a transaction
Pre-executing a transaction is optional. One of the main functions is serves is informing the user how much ONT
or ONG
is involved in a particular transaction. The Notify
message that is returned upon pre-execution can deliver the information regarding the amount of ONT/ONG
the user will spend for a particular transaction in terms of transaction costs.
The Notify
message needs to be parsed to make a judgement, because a transaction may have multiple transfer or smart contract events. If the other contract events don't need to handled, then the nature of transferred tokens can be judged from the address i.e. ONT/ONG
and the transfer
method along with the sender.
It is also advised that the the sender and amount
should be displayed on the UI
. There is a transaction fee which roughly equals to 0.01ONG
If the pre-execution is a success the response from the node is:
But if it fails, the Error
value would be greater than 0.
Code for reference
Signature verification methods | Transaction event query methods | Cyano Wallet | dAPI - Mobile provider SDK | dAPI - Mobile client SDK |
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