Abstract
This disclosure describes a voicemail store in which a provider can deposit messages for
an offline mailbox owner while an attacker who copies the server learns neither content,
nor which files form one message, nor message length or arrival time. Each mailbox holds
a hybrid classical/post-quantum key pair (e.g. X25519 + ML-KEM-1024); the private key is
stored only under two independent wraps derived from a PIN and a recovery code, each
with a key-check value. The PIN is hardened by several required legs run in parallel on
different hosts and providers, with local per-leg prehashing and peppers, combined by
HKDF. Messages are split into pieces, randomly padded to one fixed size and encrypted as
header-less chunks with random names in a pool shared by all mailboxes. A manifest is
sealed to the mailbox key and written in several identical copies; all files of a deposit share
one backdated timestamp. A signed, hash-chained ledger protects public keys and
notification addresses; unlock sessions live in RAM-backed storage and are wiped at
hangup.
Creative Commons License
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Recommended Citation
Boll, Joe, "Header-Less Pooled Storage of Encrypted Voicemail with Hybrid Post-Quantum Mailbox Keys and Multi- Provider PIN Hardening", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/12739