Signer

The signer packages (@interchainjs/cosmos, @interchainjs/ethereum, @interchainjs/injective) provide high-level transaction signing and broadcasting capabilities for different blockchain networks. All signers implement the IUniSigner interface and extend network-specific base classes, allowing them to work with both IWallet implementations and OfflineSigner interfaces.

Architecture Overview

Transaction Workflow

Core Concepts

The signer layer provides a unified interface for transaction signing and broadcasting across different blockchain networks. Key concepts include:

• Network Abstraction: The IUniSigner interface provides consistent methods regardless of the underlying blockchain
• Flexible Authentication: Signers work with both IWallet (direct key access) and OfflineSigner (external wallet) authentication
• Transaction Lifecycle: Complete transaction flow from message creation to broadcasting and confirmation
• Type Safety: Generic type parameters ensure type safety for network-specific transaction formats

Signer + IWallet

IWallet implementations provide direct access to private keys for full cryptographic control. This approach is ideal for development, testing, and applications that manage their own key security.

Usage with IWallet

import { DirectSigner } from '@interchainjs/cosmos';
import { Secp256k1HDWallet } from '@interchainjs/cosmos/wallets/secp256k1hd';
import { HDPath } from '@interchainjs/types';
 
// Create wallet from mnemonic
const wallet = await Secp256k1HDWallet.fromMnemonic(
  "<MNEMONIC_WORDS>",
  [{
    prefix: "cosmos",
    hdPath: HDPath.cosmos(0, 0, 0).toString(), // m/44'/118'/0'/0/0
  }]
);
 
// Create signer with wallet
const signer = new DirectSigner(wallet, {
  chainId: 'cosmoshub-4',
  queryClient: queryClient,
  addressPrefix: 'cosmos'
});

Signer + OfflineSigner

OfflineSigner interfaces provide secure integration with external wallets without exposing private keys. This approach is ideal for production applications that need to integrate with user wallets.

Usage with OfflineSigner

import { DirectSigner } from '@interchainjs/cosmos';
 
// Get offline signer from external wallet (e.g., Keplr)
await window.keplr.enable(chainId);
const offlineSigner = window.keplr.getOfflineSigner(chainId);
 
// Create signer with offline signer
const signer = new DirectSigner(offlineSigner, {
  chainId: 'cosmoshub-4',
  queryClient: queryClient,
  addressPrefix: 'cosmos'
});

Benefits of OfflineSigner

• Enhanced Security: Private keys remain in the external wallet
• User Control: Users maintain full control over their keys
• Standard Integration: Works with popular wallets like Keplr, Leap, and hardware wallets

IUniSigner Interface

The IUniSigner interface provides a universal API for transaction signing and broadcasting across different blockchain networks:

/** Import from @interchainjs/types */
export interface IUniSigner<
  TTxResp = unknown,
  TAccount extends IAccount = IAccount,
  TSignArgs = unknown,
  TBroadcastOpts = unknown,
  TBroadcastResponse extends IBroadcastResult<TTxResp> = IBroadcastResult<TTxResp>,
> {
  // Account management
  getAccounts(): Promise<readonly TAccount[]>;
 
  // Core signing methods
  signArbitrary(data: Uint8Array, index?: number): Promise<ICryptoBytes>;
 
  // Transaction flow
  sign(args: TSignArgs): Promise<ISigned<TBroadcastOpts, TBroadcastResponse>>;
  broadcast(signed: ISigned<TBroadcastOpts, TBroadcastResponse>, options?: TBroadcastOpts): Promise<TBroadcastResponse>;
  signAndBroadcast(args: TSignArgs, options?: TBroadcastOpts): Promise<TBroadcastResponse>;
 
  // Raw broadcast (for pre-signed transactions)
  broadcastArbitrary(data: Uint8Array, options?: TBroadcastOpts): Promise<TBroadcastResponse>;
}

Key Methods

• getAccounts(): Returns all accounts managed by this signer
• signArbitrary(): Signs arbitrary binary data for authentication purposes (e.g., login challenges)
• sign(): Signs transaction arguments and returns a signed transaction with broadcast capability
• broadcast(): Broadcasts a previously signed transaction to the network
• signAndBroadcast(): Combines signing and broadcasting in a single operation
• broadcastArbitrary(): Broadcasts raw transaction bytes to the network

The interface uses generic type parameters to ensure type safety while maintaining network compatibility.

Network-Specific Implementations

Cosmos Network

DirectSigner

• Import: import { DirectSigner } from '@interchainjs/cosmos'
• Signing Mode: SIGN_MODE_DIRECT (protobuf)
• Sign Args: CosmosSignArgs
• Transaction: TxRaw
• Wallet: Secp256k1HDWallet
• Account: AccountData

AminoSigner

• Import: import { AminoSigner } from '@interchainjs/cosmos'
• Signing Mode: SIGN_MODE_LEGACY_AMINO_JSON
• Sign Args: CosmosSignArgs
• Transaction: TxRaw
• Wallet: Secp256k1HDWallet
• Account: AccountData

Ethereum Network

LegacySigner

• Import: import { LegacySigner } from '@interchainjs/ethereum'
• Transaction Type: Legacy Ethereum transactions
• Sign Args: LegacyTransactionSignArgs
• Transaction: EthereumTransaction
• Wallet: Secp256k1HDWallet
• Account: EthereumAccountData

Eip1559Signer

• Import: import { Eip1559Signer } from '@interchainjs/ethereum'
• Transaction Type: EIP-1559 transactions with dynamic fees
• Sign Args: Eip1559TransactionSignArgs
• Transaction: EthereumTransaction
• Wallet: Secp256k1HDWallet
• Account: EthereumAccountData

Injective Network

DirectSigner

• Import: import { DirectSigner } from '@interchainjs/injective'
• Signing Mode: SIGN_MODE_DIRECT (Cosmos-compatible)
• Sign Args: InjectiveSignArgs
• Transaction: TxRaw
• Wallet: EthSecp256k1HDWallet
• Account: AccountData

AminoSigner

• Import: import { AminoSigner } from '@interchainjs/injective'
• Signing Mode: SIGN_MODE_LEGACY_AMINO_JSON (Cosmos-compatible)
• Sign Args: InjectiveSignArgs
• Transaction: TxRaw
• Wallet: EthSecp256k1HDWallet
• Account: AccountData