The problem Krtek Wallet + 2FA solves

Demo Video: https://drive.google.com/drive/folders/1sm5W6mXupJr4u48jPRc-gyBWgD5eg

A self-custodial EVM wallet for non-crypto-natives.
No seed phrase, ever. Signing in with ENS and password derives your owner key in the browser
(Argon2id), funds live in an ERC-4337 smart account, and a custom paymaster
sponsors gas so users never need ETH to make their first move.

What's built

1. Password-only login → on-chain smart account

Argon2id over (password, sha256("krtek.wallet.v1.password-key:" + handle))
deterministically derives a secp256k1 owner key in the browser. The owner key
lives only in tab memory; nothing secret touches localStorage. The same
password+handle on any device yields the same wallet — a real ERC-4337 v0.7
SCA at a CREATE2 address. See web/src/lib/password-key.ts,
PASSWORD_LOGIN.md.

2. Custom verifying paymaster (gasless onboarding)

A Bun service signs paymasterAndData for every UserOp; the on-chain
KrtekPaymaster verifies the signature in validatePaymasterUserOp. Works
on any chain you give it addresses for — anvil, Sepolia, real L2s. Users
never need ETH to make their first move. See paymaster-server/.

3. M-of-N social recovery

The SCA carries a setGuardians(address[], threshold) slot. Recovery is a
single recoverOwner(newOwner, deadline, signatures[]) call that verifies M
unique guardian sigs against a per-account replay nonce. Lose your password,
collect signatures from your friends, rotate to a fresh owner key — same SCA
address. See contracts/src/KrtekSCA.sol,
web/src/routes/Recover.tsx.

4. Phone 2FA via WebSocket relay

The SCA's validateUserOp accepts a 130-byte signature: ownerSig
(EIP-191) || phoneSig (raw secp over the userOpHash). With
lockToPhone=true, every UserOp must be co-signed by a paired phone.
Pairing flow lives in Settings → Phone 2FA; the existing mobile/
companion handles the user-side approval UX. See
web/src/lib/relay/, mobile/.

5. Sourcify APIv2 deep integration

Built specifically for the Sourcify bounty:

• Provenance Card — animated visualization of the source-files →
  metadata.json → IPFS CID → CBOR auxdata → on-chain bytecode chain
• Transformations diff — renders the transformations[] array as
  bullets and annotated hex showing constructor args / libraries /
  immutables / cborAuxdata regions in the deployed bytecode
• Multi-chain trust strip — /v2/contract/all-chains/{address}
  showing where else the same code is verified
• In-browser re-verification — applies transformations[] to
  recompiledBytecode locally, decodes the CBOR auxdata, attempts to
  reproduce the IPFS CID — proves the verification mathematically without
  trusting the public Sourcify server
• Source files drawer — every source file with a Solidity highlighter,
  the file containing the called function highlighted

Uses APIv2 (the legacy /files/... endpoints went into brownouts in May
2026), the new exact_match / match vocabulary, and proxyResolution
to follow proxies natively. See web/src/lib/sourcify.ts,
web/src/lib/sourcify-verify.ts,
web/src/components/wallet/{ProvenanceCard,TransformationsView,SourceFilesDrawer,MultiChainStrip}.tsx.

6. Multi-profile + auto-resume

Multiple wallets per device under different handles. Pairing state and SCA
caches persist per profile; logging in re-attaches the relay session
transparently. See web/src/lib/profiles.ts.

7. USB Armory MK II — hardware-attested 2FA

Same SCA cosigner slot as the phone, different transport: an i.MX6ULL
Trusted Applet (Rust, no_std, ARM TrustZone Secure World) holds a
secp256k1 key derived from the chip's DCP hardware-attestation primitive
(sk = sha256("krtek-signer-v1" || RPC.Attest)). The applet only
exposes GetPubkey, GetAddress, Approve(digest) and Health — it
has no ExportSecret method, so the key never crosses the syscall
boundary back to Normal World. Pulling the SD card and cloning storage
doesn't yield the key; the DCP secret is silicon-locked.

End-to-end: web app → armory-bridge/ (Bun + Hono on :4141) →
nc 10.0.0.1:4000 (USB-CDC-ECM bridge) → applet → 65-byte recoverable
ECDSA signature → web concatenates ownerSig || armorySig into the
same 130-byte UserOp signature shape the phone path produces. The SCA
verifies with one ECDSA.recover call per signature; it doesn't care
whether the cosigner is a phone or an Armory.

web/src/lib/send.ts runs decideCosigner(sender): if the Armory's
deterministic address matches the on-chain phoneSigner, sign via the
Armory; else if the relay-paired phone matches, sign via the phone; else
owner-only (which the contract refuses if lockToPhone=true). The
applet itself lives in the gitignored gotee_starter/ SDK fork; the
host-side wiring is armory-bridge/,
web/src/lib/armory/, web/src/components/wallet/ArmoryTfaCard.tsx.

8. Cosmic Backup — cTRNG-seeded self-recovery phrase

A 24-word BIP-39 phrase

Challenges we ran into

We had some issues setting up armory hardware device from space computer but we were able to make it work on one of the laptops.