wallet-sdk

KernelFlow Wallet SDK

A multi-chain wallet SDK in Go: an offline signing core (account derivation, address generation, transaction building and signing across major blockchain families) plus an optional online RPC layer (fetch transaction context, broadcast, query status). The two are split at the package level — the signing core pulls no network dependencies, so it stays independently auditable. It powers KernelFlow's white-label wallet products, open-sourced so it can be audited and reused.

Features

• Offline signing core — the signing/* packages pull no network code; keys never leave the process. Auditable as a network-free unit.
• Optional online layer — the rpc/* handlers fetch nonce / fees / UTXOs, broadcast, and track status when you want them; import only what you use.
• Unified interfaces — every chain implements the same AccountHandler and TxBuilderHandler contracts, so callers integrate new chains with the same code shape.
• MPC / cold-signer friendly — the Build → Sign → ConcatSignature split separates sig-hash generation from signature assembly, so the signing step can run in an isolated process (HSM, MPC node, air-gapped signer).
• Mobile bindings — a flat, gomobile-friendly façade lives in mobile/: mobile/acc and mobile/tx expose string / []byte APIs, and mobile/buildmobile.sh builds the Android AAR / iOS XCFramework.

Supported chains

Install

go get github.com/KernelFlowLabs/wallet-sdk

Requires Go 1.25+ and a C toolchain (gcc/clang): some transitive dependencies build C code via cgo.

Quick start

import (
    "github.com/KernelFlowLabs/wallet-sdk/signing"
    "github.com/KernelFlowLabs/wallet-sdk/signing/evm"
)

// Derive an account.
acc, _ := evm.NewAccountFromMnemonic(mnemonic, "m/44'/60'/0'/0/0")

// Build → Sign → assemble an EIP-1559 native transfer, fully offline.
b := evm.NewTxBuilder(&evm.Ingredient{
    TxType:          signing.TxTypeTransfer,
    ContractAddress: signing.MagicContactAddressForNative,
    Sender:          acc.Address(),
    Recipient:       recipient,
    Amount:          "1000000000000000",
    Nonce:           "0",
    GasLimit:        "21000",
    GasFeeCap:       "30000000000",
    GasTipCap:       "1500000000",
    IsLegacyTx:      "false",
}, "1")

_ = b.Build()
sig, _ := b.Sign(acc.PrivateKey())
rawTx, _ := b.ConcatSignature(sig, false) // broadcast via rpc/evm or your own RPC layer

Architecture

The offline/online split is at the package level: signing/* pulls no network dependencies — an auditable offline core — while rpc/* carries the RPC clients. Consumers that only import signing/* compile no network code.

Building and testing

go build ./...
go test ./...

Security

This is cryptographic signing software. Please read SECURITY.md before use, and report vulnerabilities privately as described there.

License

Apache License 2.0 — see LICENSE. A few files derive from third-party code under their own licenses; see NOTICE.