Adds optional decryption of ciphered secured packets, entirely in the
browser — the key never leaves the frontend.
- decode.py: _decode_secured_packet exposes 'cipher_block' (the
contiguous on-wire ciphered octets CNTR..end, ready for CBC) and
raw kic/kid bytes for algorithm selection. Additive only.
- index.html: pure-JS DES/3DES core (FIPS 46-3 bit-array tables,
parity ignored) + CBC; AES-CBC via native SubtleCrypto; both with
zero IV per TS 102 225. decryptSecured() picks the algorithm from
the KIc nibble (02 AES-CBC, 05 3DES-2K, 09 3DES-3K, 01 DES) with
key-length validation.
- UI: ciphered packets show a key-hex input + Decrypt strip below the
detail table; keys are memoized per key-set for the session in an
in-memory OTA_KEYS map — never sent to the server, never persisted.
- Decrypted results cached by cipher_block (survive live-polling
re-renders); plaintext rows rendered as CNTR/PCNTR/RC/Secured data
(decrypted) alongside the ciphertext; wrong-key guard via the
decrypted padding counter (PCNTR > remaining → "invalid padding").
- 3DES implementation validated byte-identical against openssl
des-ede3-cbc (3-key, 2-key ×3 random vectors, single-key).
No CC verification (out of scope). Tests: +2 (cipher_block
contiguity, AES registry guard) — 350 total. Version 1.19.0,
SW cache simtrace-analyser-v27.
catarrh
d21997764f