#84 Enhancement: Use a default password to encrypt in disk#86
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…ssword All mnemonics are now encrypted on disk even when the user provides no password. New prefix-tagged storage format (`default:1:`, `user:`, `plain:` legacy read-only, untagged legacy) makes each blob self-describing. Lazy migration converts existing `plain:` wallets to `default:1:` on next read via a single choke point (`Storage.read_and_migrate_mnemonic`). Renames `is_mnemonic_encrypted` → `requires_user_password` across all 9 production + 7 test call sites to correctly distinguish on-disk encryption from user-password requirement. Adds 21 unit tests covering prefix detection, migration round-trip, truth table, signing flows, atomicity, and write-failure tolerance.
Cover the four malformed prefix shapes that retrieve_mnemonic must
reject with a "Malformed default-encrypted mnemonic prefix" error
("default:", "default:novalidversion", "default::blob", "default:abc:blob"),
plus a regression test that the error message truncates arbitrarily
long inputs to avoid leaking ciphertext in logs.
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Purpose
Encrypt every mnemonic at rest, even when the user provides no password. Previously, wallets imported without a password stored the mnemonic as base64-only plaintext (
plain:prefix), making it trivially readable by any process scanning for BIP39 word patterns. A hardcoded default password is now applied automatically so no mnemonic ever lands in plaintext on disk.Closes #84 Enhancement: Use a default password to encrypt in disk
Description
This is obfuscation, not full security — the default password lives in source code and won't stop a targeted attacker with code access. The stated goal is to defeat automated plaintext-seed scanners. Wallets encrypted with a user-supplied password are unaffected and continue to require that password for signing.
Lazy migration: existing
plain:wallets are silently re-encrypted todefault:1:the first time their mnemonic is read (signing or load), with an atomic write-back. Write-back failures are logged as warnings but never break signing.Main Changes
default:1:(default-encrypted),user:(user-password),plain:(legacy read-only), untagged (legacy user-password)Storage.read_and_migrate_mnemonic(wallet, password)— single lazy-migration choke point wired atwallet.py:load_walletandbitcoin.py:sendis_mnemonic_encrypted→requires_user_passwordacross 9 production call sites (wallet.py,bitcoin.py,lightning.py,sideshift.py,changelly.py,sideswap.py) — correctly reflects that default-encrypted wallets do not need a user passworddefault:N:prefix from day one —default:1:today, rotation-ready via version integer_DEFAULT_MNEMONIC_PASSWORD+_DEFAULT_PWD_VERSION = 1constants instorage.py; unsupported versions raiseValueError(no silent fallback)0o600) preservation, write-failure tolerance viacaplog, bitcoin-side migration wiringBackwards compatibility
plain:wallets auto-migrate todefault:1:on next read — no user action requiredStorage.is_mnemonic_encryptedis removed; callers must useStorage.requires_user_password(different semantics: returnsFalsefordefault:blobs).default:1:...instead ofplain:.... Tests asserting theplain:prefix must be updated (already done in this PR fortest_tools.pyandtest_cli.py).Checklist