@aifinpay/wallet

Derive an AiFinPay agent wallet — Solana, EVM and Casper addresses (plus NEAR and Aptos) from one seed — with four tiny crypto dependencies and nothing else.

npx @aifinpay/wallet new

Generated strong passphrase and saved to ~/.aifinpay/.env

Your agent's addresses — the EVM one is the same on every EVM chain:

  EVM     0x…
  Solana  …
  Casper  account-hash-…

With --plain the first line reads Created ~/.aifinpay/agent.json (mode 600). instead.

Using this wallet with @aifinpay/mcp or @aifinpay/agent? Create it with --legacy-solana. In the default (standard) mode this package derives the Solana key from a domain-separated hash of the seed and stores that key in agent.json. @aifinpay/mcp and AiFinPayAgent.fromSolanaSecret read only that stored key and derive the EVM and Casper keys from it, so they run the agent at different EVM and Casper addresses from the ones this CLI prints. Only legacy-solana wallets derive the same addresses as the full SDK. Do not fund a default-mode wallet for use with MCP.

Why this exists

@aifinpay/agent is the full SDK — it derives keys and signs transactions, so installing it pulls viem and @solana/web3.js: ~142 packages, ~157 MB. In a constrained agent sandbox that install does not merely bloat, it fails.

Making a wallet needs none of that. This package has four dependencies (~4.5 MB) — @noble/curves, @noble/hashes, bs58, tweetnacl — and installs in seconds. In legacy-solana mode it derives the same Solana, EVM and Casper addresses as @aifinpay/agent's fromSeed. The division of labour:

| | install | use for | | ----------------------------------- | -------- | ------------------------------------------------ | | @aifinpay/wallet | ~4.5 MB | create a wallet, anywhere | | @aifinpay/agent / @aifinpay/mcp | ~157 MB | pay — only when you actually settle on-chain |

The keystore this writes is ~/.aifinpay/agent.json (or $AIFINPAY_HOME/agent.json), the file @aifinpay/mcp reads. See the note above about which derivation mode MCP can use.

CLI

npx @aifinpay/wallet new                    create an encrypted keystore (refuses to overwrite an existing one)
npx @aifinpay/wallet new --plain            create an unencrypted keystore (not recommended)
npx @aifinpay/wallet new --legacy-solana    derive Solana from the raw seed (the full SDK's and MCP's derivation)
npx @aifinpay/wallet show                   print the addresses
npx @aifinpay/wallet export                 print the seed to back up
npx @aifinpay/wallet --help                 usage

A command is required: npx @aifinpay/wallet on its own exits with "command required".

Encrypted keystore (default). New wallets are encrypted with scrypt-aes-256-gcm.

• If AIFINPAY_WALLET_PASSPHRASE is set, it is the passphrase. It must be at least 16 characters and contain a lower-case letter, an upper-case letter, a digit and one of !@$.^*_+=-.
• If it is not set, the CLI generates a passphrase and saves it to ~/.aifinpay/.env and ~/.aifinpay/secrets/passphrase (both mode 600). It does not prompt.
• show needs AIFINPAY_WALLET_PASSPHRASE in the environment to open an encrypted keystore; the CLI does not read .env itself. @aifinpay/mcp needs the same variable in its env.

Known issues (recorded as failing tests in AiFinPay/sdk#96):

• The encrypted keystore currently also stores the seed (seedHex) in plaintext next to the ciphertext, and export prints it without the passphrase. Treat agent.json as a plaintext secret until this is fixed.
• About 3–4% of generated passphrases do not meet the rule above, and show then refuses them. Setting your own AIFINPAY_WALLET_PASSPHRASE avoids it.
• show cannot read a keystore written by npx @aifinpay/mcp init.

Plain keystore. --plain writes an unencrypted keystore, protected only by file mode 600.

Local development

When working from the source tree (without publishing to npm):

cd wallet/
npm ci
npm run build

node dist/cli.js new
node dist/cli.js show
node dist/cli.js export
node dist/cli.js new --plain

Non-interactive use with your own passphrase:

export AIFINPAY_WALLET_PASSPHRASE='Correct-Horse-Battery-9'   # ≥16 chars, upper, lower, digit, special
node dist/cli.js new
node dist/cli.js show

Library

import { deriveWallet, newWallet, walletFromSeed } from "@aifinpay/wallet";

const w = await newWallet();
w.evmAddress; // 0x… (same on every EVM chain)
w.solanaAddress; // base58
w.casperAddress; // account-hash-…
w.nearAddress; // hex Ed25519 public key
w.aptosAddress; // 0x… authentication key
w.keys.seedHex; // 32-byte seed — THE thing to back up
w.keys.evmPrivateKey; // for building your own transactions
w.keys.solanaSecretKeyB58; // tweetnacl 64-byte secret, base58

deriveWallet(w.keys.seedHex); // same seed → same wallet, deterministic

Derivation modes

standard (the default) derives the Solana key from SHA-256("aifinpay:solana:v1\0" || seed). legacy-solana derives it from the raw seed, as @aifinpay/agent and @aifinpay/mcp do. EVM, Casper, NEAR and Aptos are the same in both modes.

import { newWallet, walletFromSeed } from "@aifinpay/wallet";

// Create a wallet with the full SDK's Solana derivation
const legacyWallet = await newWallet({ mode: "legacy-solana" });

// Or recover from an existing seed in that mode
const recovered = walletFromSeed(seedHex, { mode: "legacy-solana" });

Programmatic CLI usage

import { createWalletCLI } from "@aifinpay/wallet";

// Encrypted keystore with the full SDK's Solana derivation
await createWalletCLI("new", ["node", "wallet", "--legacy-solana"]);

// Unencrypted keystore
await createWalletCLI("new", ["node", "wallet", "--plain"]);

createWalletCLI calls process.exit on its error paths (for example, when a keystore already exists), as the CLI does.

Recovery

The derivation is not BIP-39/BIP-44 — no standard wallet (MetaMask, Phantom) can recover this from a phrase. The 32-byte seed is the backup. Keep ~/.aifinpay/agent.json, or npx @aifinpay/wallet export and store the seed.

What it does not do

Sign or send anything. It returns addresses and raw keys. To pay, use @aifinpay/agent — that is when the heavier install earns its size.

MIT.