mrwnslz
695037fb9c
library.py hält die Regeln der Web-Bibliothek (53-library.js) als reine Funktionen: Status Angefangen/Ungelesen/Gelesen, Ordner (mehrere je Buch, Reihenfolge aus den verschlüsselten Bibliothekseinstellungen, "Ohne Ordner"), Suche ohne Akzente, sechs Sortierungen mit natürlicher Zahlenordnung, Weiterlesen-Karte aus den zuletzt gelesenen, Bücher/Zeitschriften. library_screen.py zeigt sie an (Tasten 1-4, o, /, s, m, c; Chips und Karte klickbar). Metadaten (Ordner, Seitenzahl, Zeitschrift) und die Ordnerreihenfolge kommen beim Abgleich; fehlt die Länge, rechnet die TUI sie für geladene Bücher aus dem Text (1800 Zeichen je Seite). crypto.encrypt für Stufe 3. 54 Tests, Smoke prüft Ordner/Länge/Prefs gegen den lokalen Server. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
59 lines
2.1 KiB
Python
59 lines
2.1 KiB
Python
"""AES-256-GCM helpers matching static/js/app.js's encryptBytes/decryptBytes
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(Web Crypto AES-GCM, 12-byte IV hex-encoded, ciphertext base64, key handled
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as raw bytes) — diora's books are end-to-end encrypted client-side, so the
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server (and this module) only ever sees ciphertext plus the key the user
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supplies out-of-band.
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"""
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from __future__ import annotations
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import base64
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import os
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from cryptography.exceptions import InvalidTag
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives.ciphers.aead import AESGCM
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from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
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_PBKDF2_ITERATIONS = 200_000
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_KEY_LENGTH_BYTES = 32
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class DecryptError(Exception):
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"""Ciphertext could not be decrypted with the given key (wrong key, or corrupt data)."""
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def decrypt(key_b64: str, iv_hex: str, ciphertext_b64: str) -> bytes:
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try:
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key = base64.b64decode(key_b64)
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iv = bytes.fromhex(iv_hex)
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ct = base64.b64decode(ciphertext_b64)
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return AESGCM(key).decrypt(iv, ct, None)
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except (InvalidTag, ValueError) as e:
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raise DecryptError(str(e)) from e
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def encrypt(key_b64: str, plaintext: bytes) -> tuple[str, str]:
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"""(iv hex, ciphertext base64): what the web client's encryptBytes sends as iv/ct."""
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iv = os.urandom(12)
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ct = AESGCM(base64.b64decode(key_b64)).encrypt(iv, plaintext, None)
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return iv.hex(), base64.b64encode(ct).decode()
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def derive_key_b64(username: str, password: str) -> str:
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"""Re-derive the AES-256 key the same way app.js's deriveAndStoreKey() does:
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PBKDF2-HMAC-SHA256, 200000 iterations, salt = "diora:" + username. Only
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yields the key that actually decrypts a user's books if that account's
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key was ever set up via diora's "unlock with password" flow — a browser
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that only ever auto-generated a random key (the default) has a key this
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can't reproduce.
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"""
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salt = f"diora:{username}".encode("utf-8")
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kdf = PBKDF2HMAC(
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algorithm=hashes.SHA256(),
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length=_KEY_LENGTH_BYTES,
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salt=salt,
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iterations=_PBKDF2_ITERATIONS,
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)
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raw = kdf.derive(password.encode("utf-8"))
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return base64.b64encode(raw).decode()
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