The register can't check a password it never sees, and should its
database leak, the verifier and the keys wrapped under the password fall
to guessing at Argon2id's cost (the second reading's M8). Devices now
refuse a new password shorter than 12 characters, counted as code points
once normalised (halkyon_keys' checkNewPassword), at sign-up, a reset
keeping the keys and a change alike, before anything is derived; the new
password's field says so, and the refusal has its own text (en, de).
Signing in takes any length, so a password set before keeps working.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
A key proof was a signature by the account's signing key, which every
signed-in device keeps in its keyring: whoever could read one, with a
code from its authenticator, set a new password without the password or
the phrase (the second reading's H1). The phrase now proves itself with
an Ed25519 key derived from its bits alone (halkyon_keys'
recoveryProofKeysOf, KDF context hlkrprf1, a sibling of the recovery
key), whose public half every setup, new phrase and account reset sends
and the register keeps (account_password.recoveryProofKey); the device
derives the secret half only while the phrase is typed. An account
without one (none exist outside development) proves no phrase until it
sets a new one; decoys check against a decoy proof key alike.
Migration (module, Learn's and Todo's servers, Learn's device schema):
ALTER TABLE "account_password" ADD COLUMN "recoveryProofKey" bytea;
nullable, so rows made before keep working and no data is touched.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
Other spaces become a plain space and the text is composed (NFC) before
Argon2id, so a password typed on another system, accents composed or
not, unlocks the same keys; empty passwords and control characters are
refused. The normalisation (unorm_dart) is pinned exactly, as it must
never change once an account exists. ADR 0017 records both decisions.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
ADR 0017's step 1, on libsodium (sodium 4.1.0+1, whose build hook
compiles the libsodium 1.0.22 it ships: a C compiler and make wherever
it builds):
- Argon2id (64 MiB, 3 passes, kept with the account and never below
that) makes a master key, which libsodium's KDF splits into SRP's
secret (x) and the key-encryption key.
- The account's X25519 and Ed25519 key pairs, their private halves
wrapped with XChaCha20-Poly1305 under the KEK and under the recovery
key, bound to their public keys.
- A 24-word BIP-39 recovery phrase (the English list, MIT) and the
recovery key derived from it.
- Data keys sealed to the account with crypto_box_seal, bound to their
IDs; content in ADR 0002's envelope, encrypted with a data key and
signed with Ed25519 (detached), bound to a context the caller names.
- Secrets in libsodium's guarded memory where its API takes them.
- Tests: libsodium's Argon2id known answers, BIP-39's English vectors,
round trips and every refusal.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
