Sample
Configure Plug.Session cookie storage, signing salts, 64-byte secret key constraints, and lazy cookie serialization
sha256:3ef390aae7cf632653e7ba065c15143a68dcd2829bcc012a4bf60960c4dcda4b
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- elixir
- Operating system
- linux
- Architecture
- x64
- Runtime
- elixir
- Language
- elixir
- Package manager
- mix
Verification-run environments
- Execution context
- elixir 1
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- elixir 1
- Language
- elixir
- Package manager
- mix
- Execution
- container · docker
CONTAINER_RUN · compile:PASS · contract:PASS · load:PASS · resolve:PASS · hex@1 · 2026-08-17
Case
- Goal
- Configure Plug.Session cookie storage, signing salts, 64-byte secret key constraints, and lazy cookie serialization HOW
- Packages
-
plug 1.20.3
- Environment
- elixir
- Created
- 2026-08-17T10:30:17Z
Commonly assumed
Plug.Session validates secret_key_base at initialization alongside signing_salt and accepts standard 32-byte keys for cryptographic signing.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- assert Plug.Session.init/1 enforces :signing_salt for cookie storage at initialization but defers :secret_key_base validation until runtime, where omitting it or providing fewer than 64 bytes raises ArgumentError only when fetching or writing cookies
- assert calling get_session/2 before fetch_session/2 raises ArgumentError stating the session is not fetched
- assert read-only session inspection never emits a set-cookie response header, while session mutations register a before_send callback to emit signed cookie headers with HttpOnly and path=/
- assert tampered or forged incoming cookie signatures are silently dropped with an empty session map rather than raising a runtime decoding error
- assert configuring :encryption_salt upgrades session payload handling from base64-encoded signed plaintext to AES-GCM ciphertext
- assert configure_session(conn, drop: true) on an active session emits a set-cookie header with max-age=0 to expire the cookie on the client
Files
- NOTES.md
- csx.json
- lib/csx_plug_session/session_pipeline.ex
- mix.exs
- mix.lock
- test/contract_test.exs
- test/test_helper.exs
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- elixir 1 · linux alpine/x64 · docker · CONTAINER_RUN · compile:PASS · contract:PASS · load:PASS · resolve:PASS · hex@1 · 2026-08-17 · ed25519:d91480838ac982c9