feat: bind an auth challenge to the operation it authorises - #1546
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This repository does not receive automatic reviews because it has fewer than 10 stars. ⚙️ Run configurationConfiguration used: Path: .coderabbit.yaml Review profile: CHILL Plan: Pro Plus Run ID: WalkthroughThe change introduces operation-specific step-up challenges and separate SIWE nonce pools for login and wallet linking. The API, Rust engine, WASM host, client transports, web linking flow, OpenAPI contract, and authentication tests now carry and validate explicit operation intent. ChangesOperation-bound authentication
Estimated code review effort: 5 (Critical) | ~120 minutes Merge Risk: 🔵 Low · up to The PR strengthens authentication proof binding across login, linking, and unlinking, but one integration test does not isolate the intended nonce-pool rejection because it uses an invalid signature. The change is mergeable with explicit owner follow-up to use a valid wallet signature so regressions in cross-operation protection cannot be masked. Sequence Diagram(s)sequenceDiagram
participant WebApp
participant EngineClient
participant WASMEngine
participant AuthAPI
WebApp->>EngineClient: siweChallenge('link')
EngineClient->>WASMEngine: forward link intent
WASMEngine->>AuthAPI: POST /auth/siwe/link-challenge
AuthAPI-->>WASMEngine: link-bound SIWE nonce
WASMEngine-->>WebApp: nonce
🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
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In `@crates/contract/tests/contract.rs`:
- Around line 401-426: Update a_sign_in_nonce_is_refused_at_the_link_route to
generate a valid signature for the existing message using the test signer
instead of the hard-coded repeated 0xab value. Preserve the expected link
statement and existing Unauthorized and auth-method assertions so the test
isolates rejection of the nonce from the wrong pool.
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📒 Files selected for processing (37)
apps/api/openapi.jsonapps/api/src/auth/auth.controller.tsapps/api/src/auth/auth.http.itest.tsapps/api/src/auth/dto/auth.dto.tsapps/api/src/auth/services/auth.service.test.tsapps/api/src/auth/services/auth.service.tsapps/api/src/auth/services/challenge.service.test.tsapps/api/src/auth/services/challenge.service.tsapps/api/src/auth/services/identity-exchange.service.tsapps/api/src/auth/services/siwe.service.test.tsapps/api/src/auth/services/siwe.service.tsapps/web/src/components/settings/AuthMethodsPane.test.tsxapps/web/src/hooks/useAuthMethods.tsapps/web/src/test/authFakes.tsxcrates/contract/tests/contract.rscrates/engine/src/api/client.rscrates/engine/src/api/types.rscrates/engine/src/facade.rscrates/engine/src/lib.rscrates/engine/tests/facade.rscrates/wasm/src/host.rspackages/client/src/broadcast.tspackages/client/src/broadcastTransport.test.tspackages/client/src/broadcastTransport.tspackages/client/src/correlatedTransport.tspackages/client/src/engineClient.tspackages/client/src/facade.test.tspackages/client/src/facade.tspackages/client/src/index.tspackages/client/src/leaderRelay.tspackages/client/src/testkit.tspackages/client/src/transport.tspackages/client/src/worker/engineHost.tspackages/client/src/worker/engineWasm.tspackages/client/src/worker/protocol.tspackages/client/src/worker/serve.test.tspackages/client/src/worker/serve.ts
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One nonce pool served login and link in each protocol family, so a (challenge, signature) pair was accepted by whichever route of the pair received it first. The statement binding closed the named phishing route by string comparison; this replaces it with a structural split. ChallengeKind now names the operation: identity-login, identity-link, identity-unlink, siwe-login, siwe-link. Each identity operation stamps its own domain tag on the challenge, so the bytes the identity key signs state what the signature authorises. Two owner-authenticated mints serve the account-management operations: POST /auth/challenge/step-up takes the operation and reads the key off the session, and POST /auth/siwe/link-challenge issues the only nonce POST /auth/siwe/link accepts. The engine holds each operation to its own tag before the challenge reaches the identity key, and Engine::siwe_challenge takes the intent that picks the pool. The intent crosses the wasm boundary as a string and maps fail-closed.
The three authoring gates on the diff turned up two live gaps and a set of quality items. The SIWE link pool bound no account, so one member's session could spend a nonce another member's session minted — a wallet a victim signed for their own account could be redirected onto the attacker's. The link nonce now binds the minting account, and consume compares it. The signed bytes name the operation and never the operand, so a captured unlink proof authorised the removal of any method the account held. The step-up mint now names the row an unlink may remove, and refuses to name one for any other operation. consume also no longer burns a challenge on a binding mismatch, so a caller who does not match cannot destroy a live challenge the rightful account is about to use. The two guarded mints drop AuthMetricsInterceptor, which runs after the guards and so would report a flawless series under a token flood. Quality: the wire operation renders through serde, the domain tags have one home, the step-up kind map is a fail-closed template, the controller reads the session key through one helper, and the rationale stands once at each type rather than on every caller.
a_sign_in_nonce_is_refused_at_the_link_route sent an all-0xab wallet signature, so the 401 it asserted had two possible sources. If the two SIWE nonce pools merged again, the link route would reach the SIWE verifier and answer 401 for the signature instead, and the leg would stay green. The assertion could not fail on the regression it named. A valid EIP-191 wallet signature is the only way to make that leg discriminate, and crates/contract cannot build one: the Rust workspace has no keccak256 and no recoverable secp256k1 signer, and AGENTS.md keeps crypto inside crates/core. The discriminating cover already exists where viem can sign for real: apps/api/src/auth/auth.http.itest.ts, 'refuses a sign-in nonce spent as a link, statement notwithstanding'. It uses a real wallet signature, the link statement, and a valid identity re-proof, so only the pool can refuse it. Its neighbour adds a 200 positive control. Both run in the merge-blocking API Integration job.
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CodeRabbit review dispositionReview of 2026-08-27T10:08:27Z. One actionable comment, no nitpicks. Every item is listed below. 1. The leg could not fail on the regression it named. In The suggested fix is not possible in that crate. A discriminating leg needs a valid EIP-191 wallet signature, which means keccak256 plus a recoverable secp256k1 signer. The Rust workspace has neither, and AGENTS.md keeps crypto inside The discriminating cover already exists where viem can sign for real, in
Both run against real Postgres in the merge-blocking API Integration job. The vacuous duplicate is therefore removed, not kept with a claim it cannot support. No other change. The domain shape of the PR is unchanged: challenge kinds still name the operation, each identity operation keeps its own domain tag, challenges stay in memory, and the step-up mint still reads the key off the session and binds the |
1 participant
Mechanism
ChallengeServicenamespaced a challenge by protocol, never by operation.ChallengeKindwas'identity' | 'siwe', so one pool served two routes in each family:'siwe'pool servedPOST /auth/siwe/login,POST /auth/siwe/linkandPOST /auth/identity/wallet'identity'pool servedPOST /auth/login,POST /auth/unlinkand the link route's re-proofNothing in the signed bytes said what the signature authorised. A
(challenge, signature)pair was therefore accepted by whichever route of the family received it first.POST /auth/siwe/challengeis unauthenticated, so an attacker could mint a nonce freely, phish an ordinary-looking sign-in prompt, and post the victim's message and signature to the link route under their own bearer.The statement binding that shipped with #1296 closed the named attack by string comparison. This replaces that comparison with the structural split it stood in for. The statement check stays: it costs nothing and it is what a member reads in the wallet prompt.
Fix
The kinds name the operation.
identity-login,identity-link,identity-unlink,siwe-login,siwe-link. The pools are disjoint, so a cross-operation spend fails insideconsumewith no string comparison anywhere.Each identity operation stamps its own domain tag.
cipherbox-login:v2:,cipherbox-link:v2:andcipherbox-unlink:v2:, each followed by the same 32-byte lowercase-hex tail. The tag sits inside the bytes the secp256k1 identity key signs, so the signature itself states what it authorises.Two owner-authenticated mints.
POST /auth/challenge/step-uptakes{ operation: 'link' | 'unlink' }and reads the key off the caller's session, never off the body — a mint cannot be aimed at another account's identity key, and an attacker cannot mint one at all.POST /auth/siwe/link-challengeissues the only noncePOST /auth/siwe/linkaccepts. Both sit behindJwtAuthGuardand the auth throttle bucket.The engine holds each operation to its own tag.
is_identity_challengenow takes the prefix the operation expects, so a challenge minted for another operation never reaches the identity key.ApiClient::step_up_challengenames the operation at the mint and pins the answer.Engine::siwe_challengetakes aSiweIntentthat picks the pool; the intent crosses the wasm boundary as a string and maps fail-closed, so a typo cannot fall back to the sign-in pool.No new table. Challenges stay in memory by design: the data model is fixed to
users/auth_methods/refresh_tokensplus the registry tables (blueprint/api.md, "Data model (complete)"), and no challenge table exists.consumealready hard-deletes, the store is single-writer inside one Node process, and the change adds no DB mutation path — so it needs no advisory lock and no bulk read.A refused spend does not burn the challenge — for a wrong kind, a wrong account or a wrong row alike. The operation it was minted for still works, which the unit test pins. Burning would buy nothing an attacker who already holds the value does not have, and it would let a mismatched caller destroy a live challenge the rightful account is about to use.
What the review gates changed
All three authoring gates ran on
git diff main...HEAD. Two findings were live gaps, folded in as the second commit.The link nonce bound no account. The mint is owner-authenticated, so an attacker needs a session to get one — but the pool itself was global. One member could mint a link nonce, phish a victim into signing the link statement over it, and post the result under their own bearer: the victim's wallet lands on the attacker's account, permanently, because the unique index then denies the victim that link. The link nonce now carries the minting account, and
consumecompares it.The signed bytes named the operation and never the operand. A captured unlink proof authorised the removal of any method the account held. The re-proof exists to defeat a stolen bearer, so a stolen bearer plus one intercepted proof redirecting the operation defeats the point of it.
POST /auth/challenge/step-upnow takes themethodIdan unlink may remove, stores it on the pending entry, and refuses to bind one for any other operation. The link half needs no operand field: its wallet address is already pinned by the account-bound SIWE nonce and the signed message.The two guarded mints dropped
AuthMetricsInterceptor. NestJS runs guards before interceptors, so every 401, 403 and 429 on those routes would have counted as nothing and the panel would have read as a flawless surface under a token flood. The interceptor's own doc block states the rule, and the sibling guarded routes/auth/siwe/linkand/auth/unlinkalready omit it.Also folded, from the quality pass: the wire
operationrenders through serde rather than a hand-written match; each domain tag has one home;stepUpChallengeKindis a template literal typed to exclude the login kind, so an operation that would aim the step-up mint at the login pool stops compiling; the controller reads the session key through one helper instead of three copies; and the pool rationale stands once atChallengeKindand once atSiweIntentrather than on every caller.Deferred, with an issue
Two reviewers flagged that
POST /auth/siwe/loginandPOST /auth/identity/walletstill share thesiwe-loginpool and one statement, and that the second pays more (an identity token the Core Kit turns into the account key)./auth/siwe/loginhas no production caller, so no legitimate prompt produces a signature aimed at the weaker route and the escalation has no live source. The right fix is a decision — split the pair, or delete the route nothing calls — with plumbing inpackages/loginand copy inapps/webeither way. Filed as #1545, blocked by this one.Tests, red before green
The red was captured by collapsing the pools back to one per protocol — exactly what
maindoes today — and running the new suites against it. 16 of the new tests failed; all 15 pre-existing ones passed. The failures name each direction:apps/apiunitapps/apiintegration/auth/login; a login or link challenge refused at/auth/unlink; a sign-in nonce refused at/auth/siwe/link; an unlink redirected onto another rowcrates/engineunit/auth/challenge/step-upwith the rightoperationand nopublicKeyin the body; the link nonce comes from its own authenticated route; every hostile challenge shape plus every other operation's well-formed tag is refused before the identity key sees itcrates/contractpackages/clientapps/webThe second commit's two hardenings were red first too, by dropping only the matching check inside
consume:Docker is down on the authoring host, so the
apps/apiintegration legs could not run locally. They are written and typechecked; CI runs them. Everything else ran green locally:pnpm typecheck,pnpm lint,pnpm lint:tracker-refs, theapps/apiunit suite (440),packages/client(632),apps/web(525),cargo fmt --all --check,cargo clippy --workspace --all-targets -D warnings,cargo check -p cipherbox-wasm --target wasm32-unknown-unknown, and the fullcargo test -p cipherbox-enginesuite.apps/api/openapi.jsonis regenerated for the two new routes.Wire shape
The route set grew, so the engine's hand-written client and the contract suite moved together. No existing route's body or response changed.
Closes #1534
Note
Bind auth challenges to the operation they authorise via
SiweIntentand per-operation challenge kindsSiweIntent('login'|'link') across the client, WASM host, and engine.Engine::siwe_challengeand every transport/facade method now require an intent and route to the correct API endpoint.identity-login,identity-link,identity-unlinkand SIWE nonces intosiwe-login,siwe-linkwith disjoint pools and per-operation domain prefixes.ChallengeService.consumenow enforces exact kind and binding (publicKey, optionalsubject) match and rejects cross-kind or cross-account spends without burning the original entry.POST /auth/challenge/step-up(mint an operation-bound identity challenge, withmethodIdfor unlink) andPOST /auth/siwe/link-challenge(mint a link-pool SIWE nonce). The RustApiClientgainsstep_up_challengeandsiwe_link_challengecallers;unlink_auth_methodandsiwe_linknow use step-up challenges.'siwe'and'identity'challenge kinds are removed — any out-of-tree caller that mints or consumes challenges without specifyingSiweIntentor the new kind enums will fail. Theconsumepath no longer burns the pending entry on a kind/binding mismatch, so replay attempts leave the original challenge valid.Macroscope summarized 1bbbe31.
Summary by CodeRabbit
New Features
Bug Fixes