Decoder - Buffer Boba

The primary purpose of the library is to decode the SignDoc received from dApps. We provide a couple of ways to do so.

DirectSignDocDecoder

This class is the simplest way to decode a SignDoc. You can use it in the following way:

get JSON data

import { DirectSignDocDecoder } from "@leapwallet/buffer-boba";
 
// signDoc is the SignDoc received from dApps
const signDoc = {}
 
// decoder is the instance of DirectSignDocDecoder
const decoder = new DirectSignDocDecoder(signDoc);
 
// decoded to-be txn data
const jsonPayload = decoder.toJSON();

Here the argument is a SignDoc object defined inside cosmos.tx.v1beta1.SignDoc (opens in a new tab). It looks like this:

interface SignDoc {
    /**
     * body_bytes is protobuf serialization of a TxBody that matches the
     * representation in TxRaw.
     */
    bodyBytes: Uint8Array;
    /**
     * auth_info_bytes is a protobuf serialization of an AuthInfo that matches the
     * representation in TxRaw.
     */
    authInfoBytes: Uint8Array;
    /**
     * chain_id is the unique identifier of the chain this transaction targets.
     * It prevents signed transactions from being used on another chain by an
     * attacker
     */
    chainId: string;
    /** account_number is the account number of the account in state */
    accountNumber: Long;
}

We have another method called decode on the DirectSignDocDecoder class which returns the decoded payload as a Uint8Array. You can use it in the following way:

import { DirectSignDocDecoder } from "@leapwallet/buffer-boba";
 
// signDoc is the SignDoc received from dApps
const signDoc = new Uint8Array([/* ... */]);
 
// decoder is the instance of DirectSignDocDecoder
const decoder = DirectSignDocDecoder.decodeBytes(signDoc);
 
// decoded to-be txn data
const jsonPayload = decoder.toJSON();

Methods

`constructor`

constructor(signDoc: SignDoc, protoCodec?: ProtoCodec): DirectSignDocDecoder

The constructor takes in a SignDoc object and an optional ProtoCodec object. The ProtoCodec object is used to decode the messages in txBody. If not provided, it will use the defaultProtoCodec object.

`toJSON`

toJSON(): { txBody: TxBody, authInfo: AuthInfo, chainId: string, accountNumber: string }

This method returns the decoded payload as an object.

`decodeBytes`

static decodeBytes(signDoc: Uint8Array, protoCodec?: ProtoCodec): DirectSignDocDecoder

This method takes in a SignDoc object as a Uint8Array and an optional ProtoCodec object. The ProtoCodec object is used to decode the messages in txBody. If not provided, it will use the defaultProtoCodec object.

`toBytes`

toBytes(): Uint8Array

This method returns the SignDoc as a Uint8Array.

Properties

`txBody`

txBody: TxBody

This property returns the decoded TxBody object.

/** TxBody is the body of a transaction that all signers sign over. */
interface TxBody {
    /**
     * messages is a list of messages to be executed. The required signers of
     * those messages define the number and order of elements in AuthInfo's
     * signer_infos and Tx's signatures. Each required signer address is added to
     * the list only the first time it occurs.
     * By convention, the first required signer (usually from the first message)
     * is referred to as the primary signer and pays the fee for the whole
     * transaction.
     */
    messages: Any[];
    /**
     * memo is any arbitrary note/comment to be added to the transaction.
     * WARNING: in clients, any publicly exposed text should not be called memo,
     * but should be called `note` instead (see https://github.com/cosmos/cosmos-sdk/issues/9122).
     */
    memo: string;
    /**
     * timeout is the block height after which this transaction will not
     * be processed by the chain
     */
    timeoutHeight: Long;
    /**
     * extension_options are arbitrary options that can be added by chains
     * when the default options are not sufficient. If any of these are present
     * and can't be handled, the transaction will be rejected
     */
    extensionOptions: Any[];
    /**
     * extension_options are arbitrary options that can be added by chains
     * when the default options are not sufficient. If any of these are present
     * and can't be handled, they will be ignored
     */
    nonCriticalExtensionOptions: Any[];
}

`txMsgs`

txMsgs: AnyWithUnpacked[]

Returns the messages in the TxBody object.

type Any = {
    typeUrl: string;
    value: Uint8Array;
};
 
type AnyWithUnpacked = Any | (Any & { unpacked: unknown; toJSON: () => any });

Any is a protocol buffer message defined here - https://github.com/protocolbuffers/protobuf/blob/main/src/google/protobuf/any.proto (opens in a new tab)

`authInfo`

authInfo: AuthInfo

This property returns the decoded AuthInfo object.

/**
 * AuthInfo describes the fee and signer modes that are used to sign a
 * transaction.
 */
export interface AuthInfo {
    /**
     * signer_infos defines the signing modes for the required signers. The number
     * and order of elements must match the required signers from TxBody's
     * messages. The first element is the primary signer and the one which pays
     * the fee.
     */
    signerInfos: SignerInfo[];
    /**
     * Fee is the fee and gas limit for the transaction. The first signer is the
     * primary signer and the one which pays the fee. The fee can be calculated
     * based on the cost of evaluating the body and doing signature verification
     * of the signers. This can be estimated via simulation.
     */
    fee?: Fee;
}

`chainId`

chainId: string

This property returns the chain ID.

`accountNumber`

accountNumber: string

This property returns the account number.

Getting Started Proto Codec