feat(wallet): encrypt private keys at rest using eth-keystore

[Aboudjem]

Summary

• Private keys are now encrypted at rest using AES-128-CTR + scrypt (via Alloy's keystore)
• Password prompt on wallet create/import, with POLYMARKET_PASSWORD env var for CI/automation
• Backward compatible: detects plaintext keys and offers automatic migration
• New wallet export subcommand to decrypt and display key when needed
• Key resolution priority: --private-key flag → env var → auto-migrate → keystore prompt

Changes

File	What
src/password.rs	New module: password prompting with retries + env var fallback
src/config.rs	Keystore encrypt/decrypt, migration logic
src/auth.rs	Updated key resolution chain
src/commands/wallet.rs	create/import use encryption, new export subcommand
src/commands/setup.rs	Uses encrypted save path
Cargo.toml	Added alloy/signer-keystore, rpassword, rand, secrecy

Test plan

• cargo clippy -D warnings — clean
• cargo fmt --check — clean
• 84 unit + 49 integration tests passing
• New tests: keystore round-trip (encrypt → decrypt same address) + wrong-password rejection

Fixes #18

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Note

Medium Risk
Touches wallet key storage and authentication key-resolution paths; while changes are localized, mistakes could lock users out of keys or mishandle secrets during migration/export.

Overview
Private keys are no longer stored in plaintext config. Wallet creation/import now encrypts the key into a keystore.json (via Alloy keystore) and writes config.json with only non-sensitive settings.

Key resolution is updated to support password-protected keystores (with retry + POLYMARKET_PASSWORD env var) and includes auto-migration from legacy plaintext config on first use. Adds a new wallet export command to decrypt and print the private key, updates setup/wallet flows accordingly, and expands dependencies (alloy signer-keystore, secrecy, rpassword, rand) plus lockfile updates.

^{Written by Cursor Bugbot for commit 52452f6. This will update automatically on new commits. Configure here.}

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Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

Redundant costly scrypt decryption after migration

Medium Severity

After migration, resolve_key_string calls config::load_key_encrypted(password.expose_secret()) to decrypt the keystore that was just encrypted moments earlier. Since scrypt is intentionally slow (~1–2 seconds with default parameters), this doubles the wait time during migration. The plaintext key is already available inside migrate_to_encrypted (from load_config()) but is discarded. Having migrate_to_encrypted return the key would avoid the redundant scrypt computation.

Additional Locations (1)

• src/config.rs#L187-L201

 

[cursor]

Config file errors silently swallowed in resolve_key

Low Severity

resolve_key changed from returning Result<(Option<String>, KeySource)> to (Option<SecretString>, KeySource), silently discarding load_config() errors via if let Ok(Some(config)). A corrupted or unreadable config file is now indistinguishable from "no config" — callers like cmd_show and setup::execute will report "not configured" instead of surfacing the actual parse/IO error.

Additional Locations (1)

• src/commands/wallet.rs#L180-L199