A third subkey of the password's Argon2id (context `hlkpass1`, subkey 3)
seeds an Ed25519 pair: `PasswordKeys.proofKeyPair` and `proofPublicKey`.
An account that keeps no SRP verifier proves its password by signing the
register's nonce with it, as it proves the recovery phrase; neither SRP's
verifier nor the unwrapped account keys a signed-in device keeps can make
it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
The reading of the full reading's fixes noted that the main isolate's
copies of SRP's x and the key-encryption key, Dart's own bytes, stayed
for as long as the sign-in sheet's cubit lived, and after every change's
proof.
PasswordUnlock.forget zeroes them: the sign-in cubit wipes what the
password unlocked once signed in, once another password replaced it, and
as it closes; a change's or deletion's proof wipes what it unlocked once
its answer is made. The fake crypto's proof copies its bytes, as a real
one is new bytes. halkyon_keys' README says what is wiped and what isn't.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
Wrapping the account's keys and sealing a data key spread extractBytes()
copies into the buffer libsodium encrypts: the buffer was wiped, the
copies on the way weren't. The keys now go from guarded memory straight
into it (runUnlockedSync), and the seed derived to check a signing key is
disposed. The README said key bytes copied to the Dart heap were wiped
afterwards; it now says exactly which are, and which Dart can't wipe (x as
a BigInt, Strings, what isolates copy, the keyring's base64).
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>
