SRP's identity and the recovery phrase's proof carried the host alone, so
instances on one host under another port, path or scheme could relay each
other's proofs (the full reading's device low 4). Both now carry the base
URL the device addresses, written alike on both sides
(canonicalInstanceUrl: scheme and host in lower case, the port only where
it isn't the scheme's own, the path ending in /); the register takes its
own public scheme, host and port (Serverpod serves at the root), a member
the URL it names, development anything.
The identity also gains a purpose and the digest of what a proof sets,
both empty so far (signing in), with the framing for a new phrase's and an
authenticator's digest beside the new password's: the owner's proofs bind
them next. Cross-tests hold both sides to the same bytes. OwnerProof's and
DeletionProof's host, and every endpoint's, become instanceUrl.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
Two of the fourth reading's lows:
- A signed-in proof whose call to the register failed
(RegisterUnavailableException, a member's call timing out after the
register checked it) stays counted against the session, rather than
taken back: a guess never goes uncounted.
- A sign-up code also gives an existing account with that address its
first password, which its mail now says in the subject too ("create an
account or give it a password").
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 fourth reading's first finding: password.set took a session alone,
so whoever took one made a GitHub-only account, or an address account
without a password, theirs for good (their address or password, their
authenticator; GitHub then refused the owner).
- An account with an address proves it anew: a code mailed to that
address for this (EmailCodePurpose.firstPassword, its own mail), never
the session alone, a code asked for anything else, or another address.
- An account that signs in with GitHub alone does it within 10 minutes of
a GitHub sign-in (the session's method and creation time, where the
session lives; members tell the register), refused signInAgain before
any code is used; the address it adds is proved as before.
- Anonymous people still become identified with a code to the address
they add.
The app mails the code to the person's own address (asking for it where
the device doesn't know it), offers a password right after a GitHub
sign-in (D2's "at their next sign-in") before the person's app, and asks
for a GitHub sign-in anew when the instance refuses an older one, keeping
the code typed.
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 notification shows a mail's subject alone, and the subject said only
"K7QX-M2PD is your Halkyon Learn code" whatever the code would do (the
third reading). The subject now says it: to create an account, finish
setting it up, switch off the authenticator, reset or delete the account.
The sign-up mail also says that the code gives a password to an account
that has the address and none yet, as signing up does.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
Codes by mail were tied to nothing but their address (the re-review's
seventh finding): a hostile instance could answer that a setup never
finished, have the person type a code into it, relay it to start the real
instance's account reset, and 72 hours later relay a second to finish it
with its own password and keys; the mail said "to sign in" whatever the
code was for. A code is now asked for a purpose (signUp, finishSetup,
authenticatorReset, accountReset, deletion), only that purpose takes it (any
other is refused as no longer valid, leaving the code as it was), and its
mail says what it would do ("to reset your account on learn.halkyon.eu: a
new password and new keys, and what was encrypted with the old ones is
lost") and to type it only in the app on that instance, nowhere else. The
app asks for each code with the purpose of its step.
Migration (module, Learn's and Todo's servers, Learn's device schema):
ALTER TABLE "email_code_request" ADD COLUMN "purpose" text; nullable,
so the requests of the last 15 minutes before it stay, taken by nothing
and forgotten within the hour.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
One household's line or one server gets a whole /64 of IPv6 addresses,
and could turn through them past every per-network limit (the second
reading's M5). networkOf now counts an IPv6 visitor by their /64
(networkKeyOf), an IPv4 visitor by their address as before.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
Nothing tied a sign-in's proof to the instance it was made for: an
instance a person was lured into adding could pass A, M1 and the code on
to the real register and get a session there, and pass a phrase's proof
on with a password of its own in place of the person's (the second
reading's M6). SRP's identity is now a label, the challenge's ID and
the host the device addressed (passwordIdentity, in halkyon_base_client
and halkyon_base_server alike), and the phrase's proof signs that host,
what it is for (an authenticator's reset or a new password) and the new
password's digest (key proof v2). Every proving call carries the host;
in production it must be the server's apiServer.publicHost (otherwise
otherInstance, which the app shows as an instance it can't trust), in
development any; a member forwards its own. The tests prove that a
relayed sign-in, a proof for another host or purpose, and a swapped
password are refused, nothing changing.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
An address nobody has got, as the recovery phrase's first step, an
X25519 public key of 32 HMAC bytes, which is a point of Curve25519's
prime-order subgroup one time in sixteen, as every real key is: whoever
checked could tell nearly always whether an address has an account (the
second reading's M1). The decoy's key is now made from a seed, as its
Ed25519 key already was. The tests hold twenty decoys to the curve check
the review used.
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, step 3: halkyon_app's side, which Learn and Todo take.
- The account's cryptography on the device (`SodiumAccountCrypto`):
halkyon_keys and SRP's client half, each step on an isolate of its
own. sodium hands out results as views of native memory its
finalizers free once the isolate that made them ends, so everything
crossing back is copied first: a view read freed memory and crashed
the process.
- `PasswordGateway` on the module's endpoints (steps without a session
through a client holding none; an authenticator set up with a session
granted but not yet the device's), and `PasswordRepository` running
the flows: signing in (M2 checked, the keys opened before anything is
trusted), signing up, a password for someone signed in, an account
never finished, the authenticators, recovery codes, changing the
password, a new recovery phrase, and getting back in.
- The unlocked keys in the system's keyring per instance and person
(`SecureAccountKeyStore`), gone once another person signs in or
nobody, and with the instance's removal.
- The screens: the start screen's Sign in and Create an account (and
when GitHub sign-in ends), the sign-in sheet (codes, recovery codes,
an account never finished, a lost authenticator), the account's setup
(the recovery phrase shown once, three random words typed back before
anything reaches the instance; the authenticator's QR code, drawn
with pub.dev's qr; the recovery codes), getting back in, and the
account section (`AccountSecuritySection`).
- `FileSaver` moves from Learn into halkyon_app, for the phrase and the
codes in Todo too; `AppDependencies` names it and `passwords`.
- halkyon_keys rebuilds account keys from the secret keys a device kept;
the key proof's message is in halkyon_base_client, checked against
the register's.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
Every per-network limit counted by the connection's address, which behind
Caddy is Caddy's for everyone: new anonymous accounts, codes by mail and
password sign-ins were each limited for the whole instance.
`networkOf` (now `common/network.dart`) takes the last address of
X-Forwarded-For, the one the proxy saw itself, for a connection from a
proxy the operator trusts (`TRUSTED_PROXIES`, which deploy/compose.yaml
sets to Caddy's fixed address); otherwise, or where that is no address,
the connection's. Never the Forwarded header, which Caddy passes on as
sent, so never Serverpod's `remoteInfo`. A value that isn't addresses
stops the server as it starts.
Serverpod's own limit on anonymous accounts counts by the connection's
address too and can't be told otherwise, so it is off; the anonymous
endpoint counts them itself, 30 an hour per network as before.
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 register's side of signing in with an address, a password that never
leaves the device (SRP-6a) and a code from an authenticator (ADR 0017),
with members forwarding every step through AccountRegister:
- password.set: salt, Argon2id's costs, SRP's verifier, the public keys
and the private keys wrapped twice, all made on the device; with the
address a mailed code proves, an anonymous person becomes identified
under their ID. It signs in once an authenticator is confirmed.
- passwordSignIn.begin and complete: SRP's two steps with a TOTP or
recovery code. An address nobody has is answered from a decoy key as
an account would be; every wrong credential is refused alike.
- authenticator: secrets sealed under totpKey (XChaCha20-Poly1305, bound
to their row), each code accepted once, ten recovery codes with the
first, the last one kept.
- accountRecovery: a lost authenticator reset 72 hours after the
password and a mailed code or the recovery phrase ask, a lost password
set anew with the phrase's signature, or the account reset with new
keys 72 hours after a mailed code asks; a mail at each start, a
sign-in calling it off.
- An account with a password no longer signs in by a mailed code or
GitHub; no new GitHub account is linked where passwords are offered,
and from GITHUB_SIGN_IN_ENDS GitHub signs nobody in and its IDs go.
Five tables, added by the module's migration; deletePerson deletes
their rows.
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 code holds 40 bits, which plain SHA-256 hashes in a leaked database
would give up to guessing; HMAC-SHA256 under a key of the instance kept
outside the database (recoveryCodeKey, at least 32 characters) gives
nothing to guess against without it. Decided 20 Oct 2026.
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 second factor, in halkyon_base_server (base.dart):
- RFC 6238 with HMAC-SHA1, 6 digits, 30-second steps, one step either
way. checkTotp takes the account's last accepted step as a required
argument and refuses a code of that step or before, so no code is
accepted twice; every step of the window is computed and compared.
- 160-bit secrets in RFC 4648 Base32 (strict decoding); the otpauth
URI with issuer and account escaped.
- Ten recovery codes of eight Crockford characters (short_code.dart),
kept as SHA-256 hashes, each used once, every hash compared in
constant time.
- Tests: RFC 6238 Appendix B (8 digits, SHA-1, SHA-256, SHA-512), the
window, replay, RFC 4648's Base32 vectors, the recovery codes.
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. Generic over group and hash (SrpGroup); production
takes RFC 5054's 3072-bit group with SHA-256. k = H(N | PAD(g)),
u = H(PAD(A) | PAD(B)), K = H(PAD(S)),
M1 = H(H(N) xor H(g) | H(I) | s | PAD(A) | PAD(B) | K),
M2 = H(PAD(A) | M1 | K). A and B must lie in 1..N-1 and u must not be
0; a and b are 256 bits from Random.secure(); proofs are compared in
constant time. x comes from the caller (halkyon_keys makes it); RFC
5054's own x is there for the vectors only.
- The register's half in halkyon_base_server (base.dart: srpChallenge,
srpVerify), the device's written by hand in halkyon_base_client
(srp.dart: SrpClient, srpVerifier). Serverpod's generator cleans and
writes only a client's lib/src/protocol/ (serverpod_cli 4.0.4's
_getDirectoriesRequiringCleaning; a generate leaves srp/ untouched).
- Tests: RFC 5054 Appendix B on both halves; the client against the
register, succeeding and every refusal.
- The module's tests depend on its client, and pub resolves every
member's dev dependencies, so Learn's server image takes the module's
client into its workspace too.
- The format check covers the hand-written half.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
halkyon_base runs as the instance's register or as one of its members.
The register keeps the ways in, handles and profiles; members ask it
over HTTP with the instance's shared secret (instanceSecret), and open
sessions of their own for its accounts, under the same account ID.
- AccountsMode from the environment: INSTANCE_MEMBERS on the register,
ACCOUNT_REGISTER_URL on a member. Learn always holds the register
(Explore joins the profiles); Todo is a member where it is set.
- AccountRegister: LocalRegister, RemoteRegister, an in-memory one in
tests. Calls between services on the web server, refused without the
secret (constant-time compare); a server needing it doesn't start
without it.
- Deleting an account deletes it everywhere: notices per member kept in
the deletion's transaction (account_deletion_notice), told at once and
hourly until confirmed; members prune daily whom the register no longer
knows, never while it knows none of them or can't be reached.
- Deploy: INSTANCE_SECRET and INSTANCE_MEMBERS in compose and .env.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
People's public profiles are the instance's register's (ADR 0016), so
the module now holds them: the public_profile table (unchanged, so
Learn's migration records versions only; devices get the table empty,
as they hold every module's tables), the profile and profiles
endpoints under `base`, the handle rules, the link checks and the page
at /@handle, whose foot names the app as the host's configuration says
(profilePageNote). Deleting a person deletes their profile in the
module's core.
Hosts read profiles through the module (profileOf, profilesOf,
personWithHandle, fixHandle; saveProfile for their tests), behind an
AccountRegister that is this server's own database for now. Learn's
feedback, discussions and publishing ask it; publishing fixes the
handle just before it writes the release, outside its transaction.
Explore still joins the table in its search, so Learn holds the
register wherever it runs. Learn's app calls the module's endpoints;
a profile not found is ProfileNotFoundException. Todo's database gets
the table too (it was never deployed).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
An operator's DATA_LOCATION and BACKUP_LOCATION may name a subdivision
(ISO 3166-2, US-CA, DE-BY) besides the EU or a country. The app adds
"(EU)" to a member country and the country to a subdivision ("Germany
(EU)", "California, United States", "Bavaria, Germany (EU)"), in
English and German, and shows the most specific flag there is: a
subdivision's own where the flag package has one, else its country's.
Subdivision names come from Unicode CLDR 48.2 (tool/subdivision_names.py),
bundled with their licence, which the app registers.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
What every Halkyon server has, taken from Halkyon Learn's: anonymous,
GitHub and email-code sign-in with their endpoints, an account's ways
in and its deletion, the pruning of abandoned anonymous people, of
sign-up attempts and of expired codes, and the instance's basics (the
sign-in ways offered, the source link, the minimum app build, where
people's data and its backups are). Endpoints sit under the nickname
`base`. A host configures it in one place before its pod starts: its
name for the mails, its source link, its minimum build, and hooks that
delete its own data with a person.
The tables keep Learn's names, columns and indexes, so a host moving
onto the module migrates nothing but version rows. Server package under
the SSPL, client under the AGPL, as Learn's are.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
