---
title: "Beacon-Seeded Fair-Sampling Deriver"
method: POST
path: "/v1/tools/derive_beacon_fair_sample"
tags: ["TODO_TAGS_REVIEW", "TODO_AP2_EXPORT_REVIEW"]
---

# Beacon-Seeded Fair-Sampling Deriver

`POST /v1/tools/derive_beacon_fair_sample`

## Request

- Base URL: `https://ainumbers.co`
- URL: `https://ainumbers.co/v1/tools/derive_beacon_fair_sample`
- Auth: none declared

Derives a deterministic, offline-replayable audit sample by HMAC-DRBG (SHA-256) seeded from a caller-pasted public randomness beacon pulse (drand quicknet or NISTIR-8213) combined with an item-manifest hash committed before the pulse round. Emits the selected item indices plus a full per-draw derivation transcript (seed, per-draw HMAC output, candidate index, accept/reject) so an examiner re-derives the identical sample offline from the transcript alone. Verdict DERIVED, or INDETERMINATE when inputs are missing or malformed. The beacon pulse, its round and its randomness are caller-declared inputs: the kernel performs SHA-256/HMAC math only, never fetches a pulse and never verifies the pulse's BLS signature, so a sample is only as trustworthy as the pulse the caller supplied. Committing the item-manifest hash before the pulse round is what makes the selection cherry-pick-proof, and the page teaches that ordering. Extends the assurance and workpaper family; cross-links the shipped art-471 disposition-sampling-frame rather than duplicating it.

**Tool URL:** https://ainumbers.co/chaingraph/art-583-beacon-seeded-fair-sampling-deriver.html

## Request body

- object
  - `algorithm_id` unknown, required
  - `beacon_randomness` unknown, required
  - `beacon_round` unknown, required
  - `beacon_source` unknown, required
  - `item_count` unknown, required
  - `item_manifest_hash` unknown, required
  - `sample_size` unknown, required

## Response `200`

Successful tool execution result

- object
  - `algorithm_id` string
  - `beacon_randomness` string
  - `beacon_round` string
  - `beacon_source` string
  - `derivation_transcript` object[]
    - `accepted` boolean
    - `candidate_index` integer
    - `draw` integer
    - `hmac_hex` string
  - `draws_used` integer
  - `item_count` integer
  - `item_manifest_hash` string
  - `sample_size` integer
  - `seed_hex` string
  - `selected_indices` integer[]
  - `verdict` string

---

[API](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite.md) · [All operations](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite/llms.txt) · [OpenAPI document](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite/revisions/b462e4f5bb28?raw)