core: Remove Bails identifier heuristics

src/codex32/_bitcoin_core.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import hashlib
 import json
 import shutil
 import string
@@ -11,9 +10,7 @@
 from typing import Literal
 
 from codex32._bip32 import _master_xprv_from_seed
-from codex32.bech32 import _u5_to_chars, convertbits
 from codex32.bip93 import MasterSeed
-from codex32.generation import _fingerprint_identifier
 
 
 class BitcoinCoreError(Exception):
@@ -54,36 +51,6 @@ def parse_fingerprint(text: str) -> bytes:
 )
 
 
-def identifier_note(origin: str | None) -> str:
-    # Say what `identifier_origin` found, for an operator restoring without a record.
-    if origin is None:
-        return (
-            "The backup identifier was not made from this seed. That can be normal for codex32 backups "
-            "made from split shares, supplied seed bytes or an explicit identifier. Bails made every "
-            "identifier from its seed, so for a Bails backup these are the wrong or mixed-up cards."
-        )
-    return (
-        f"The backup identifier matches this seed ({origin} rule). That rules out most mixed-up cards, "
-        "but not cards replaced on purpose."
-    )
-
-
-def identifier_origin(secret: MasterSeed, fingerprint: bytes) -> str | None:
-    """Check codex32's fingerprint or Bails' three-character seed-digest identifier."""
-    identifier = secret.header.identifier
-    if identifier == _fingerprint_identifier(fingerprint):
-        return "codex32"
-    for name, digest in (("Bails", "ripemd160"), ("Bails alpha", "sha256")):
-        try:
-            hashed = hashlib.new(digest, secret.seed_bytes).digest()
-        except ValueError:
-            continue
-        derived = convertbits(hashed, 8, 5, pad=True)
-        if identifier[:3] == _u5_to_chars(tuple(derived[:3])):
-            return name
-    return None
-
-
 @dataclass(frozen=True)
 class BitcoinCore:
     executable: str

src/codex32/cli.py

@@ -14,8 +14,6 @@
     BitcoinCore,
     BitcoinCoreError,
     FingerprintMismatch,
-    identifier_note,
-    identifier_origin,
     parse_fingerprint,
 )
 from codex32._cli_input import (
@@ -56,6 +54,7 @@
     ConfirmationResult,
     CreationCeremony,
     _confirmation,
+    _fingerprint_identifier,
     generate_master_seed,
 )
 from codex32.wallet import master_xprv
@@ -323,8 +322,20 @@ def _show_fingerprint(core: BitcoinCore, secret: MasterSeed, action: str) -> Non
 def _without_record(core: BitcoinCore, secret: MasterSeed) -> bool:
     fingerprint = core.fingerprint(secret)
     _print(f"\nMaster fingerprint: {fingerprint.hex().upper()}", err=True)
-    _print(f"Backup identifier: {secret.header.identifier.upper()}", err=True)
-    _print(identifier_note(identifier_origin(secret, fingerprint)), err=True)
+    if secret.header.threshold == 0:
+        # New unshared codex32 backups take their identifier from the fingerprint.
+        if secret.header.identifier == _fingerprint_identifier(fingerprint):
+            _print(
+                "The backup identifier matches this fingerprint, so the card is consistent with itself. "
+                "That does not show it is the wallet you expect.",
+                err=True,
+            )
+        else:
+            _print(
+                "The backup identifier does not match this fingerprint. New unshared codex32 backups "
+                "take their identifier from it, so check this is the right card.",
+                err=True,
+            )
     _print(NO_RECORD_WARNING, err=True)
     return _text("Restore without a wallet record? [y/N]", optional=True).lower() in ("y", "yes")
 

tests/test_bitcoin_core.py

@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import hashlib
 import json
 import re
 import subprocess
@@ -14,12 +13,9 @@
     BitcoinCore,
     BitcoinCoreError,
     FingerprintMismatch,
-    identifier_note,
-    identifier_origin,
     parse_fingerprint,
 )
 from codex32.bip93 import MasterSeed, parse_codex32
-from codex32.generation import _fingerprint_identifier
 
 _parsed = parse_codex32("ms10testsxxxxxxxxxxxxxxxxxxxxxxxxxx4nzvca9cmczlw")
 assert isinstance(_parsed, MasterSeed)
@@ -816,44 +812,3 @@ def unused(_client: BitcoinCore, _secret: MasterSeed) -> bytes:
 
     monkeypatch.setattr(BitcoinCore, "fingerprint", unused)
     BitcoinCore("bitcoin-cli", "main", 300000).verify_identity(_SEED, None)
-
-
-# Frozen from Bails' own ms32.seed_identifier for this seed: master (RIPEMD-160) and the
-# June 2023 alpha (SHA-256). Bails checked three characters and kept the fourth for re-sharing.
-_BAILS_SEED = bytes(range(16))
-
-
-@pytest.mark.parametrize(
-    ("identifier", "origin"),
-    (
-        (_fingerprint_identifier(_FINGERPRINT), "codex32"),
-        ("d9k8", "Bails"),
-        ("d9kq", "Bails"),
-        ("hezu", "Bails alpha"),
-        ("test", None),
-    ),
-)
-def test_identifier_origin_names_the_rule_that_made_it(identifier: str, origin: str | None) -> None:
-    secret = MasterSeed.from_seed(_BAILS_SEED, identifier=identifier)
-    assert identifier_origin(secret, _FINGERPRINT) == origin
-    assert ("matches this seed" in identifier_note(origin)) is (origin is not None)
-
-
-def test_identifier_origin_still_checks_alpha_without_ripemd160(monkeypatch: pytest.MonkeyPatch) -> None:
-    original_new = hashlib.new
-
-    def without_ripemd160(name: str, data: bytes = b"") -> object:
-        if name == "ripemd160":
-            raise ValueError("unsupported hash type ripemd160")
-        return original_new(name, data)
-
-    monkeypatch.setattr(hashlib, "new", without_ripemd160)
-    secret = MasterSeed.from_seed(_BAILS_SEED, identifier="hezu")
-    assert identifier_origin(secret, _FINGERPRINT) == "Bails alpha"
-
-
-def test_identifier_note_allows_supported_nonderived_codex32_identifiers() -> None:
-    note = identifier_note(None)
-    assert "split shares" in note
-    assert "supplied seed bytes" in note
-    assert "explicit identifier" in note

tests/test_cli.py

@@ -2845,16 +2845,18 @@ def test_restore_without_a_record_shows_what_the_cards_say_and_asks(
     assert prompts[1] == "Restore without a wallet record? [y/N]"
     shown = capsys.readouterr().err
     assert shown.count(f"Master fingerprint: {fingerprint.hex().upper()}") == 1
-    assert "was not made from this seed" in shown and "nothing can prove" in shown
+    assert "nothing can prove" in shown
 
     prompts = _record_answers(monkeypatch, "", "y")
     assert _RECORDED_FINGERPRINT(core, secret) is None
     assert prompts[1] == "Restore without a wallet record? [y/N]"
+    assert "does not match this fingerprint" in capsys.readouterr().err
 
     derived = MasterSeed.from_seed(secret.seed_bytes, identifier=_fingerprint_identifier(fingerprint))
     _record_answers(monkeypatch, "", "yes")
     assert _RECORDED_FINGERPRINT(core, derived) is None
-    assert "matches this seed (codex32 rule)" in capsys.readouterr().err
+    shown = capsys.readouterr().err
+    assert "matches this fingerprint" in shown and "does not show it is the wallet you expect" in shown
 
 
 def test_wallet_restore_hides_fingerprint_until_the_record_gate(monkeypatch: pytest.MonkeyPatch) -> None: