---
license: cc0-1.0
pretty_name: Sigstore Rekor subject-digest bloom filter
tags:
- bloom-filter
- file-hashes
---

# Sigstore Rekor subject-digest bloom filter

Membership filter over sha256 subject digests recorded in the
[Sigstore Rekor](https://docs.sigstore.dev/logging/overview/)
transparency log (public dataset extract, 2026-08-01) — artifacts
that have been signed/attested via Sigstore.

- **8,202,977 sha256 keys** (lowercase hex), p = 1e-4, 19 MiB
- A hit means "something signed an artifact with this digest";
  resolve against the live Rekor API for the actual log entry

## Rebuild

See `EXTRACT.md` (BigQuery free-tier queries) + `bq_download.py` +
`./dcso_bloom_build.py rekor.sha256.bloom sha256 *.hex`.

## Format

DCSO bloom filter format (`github.com/DCSO/bloom`), the same format
CIRCL publishes hashlookup in: 48-byte little-endian u64 header
(version, n, p, k, m, N) followed by the bit array. Keys are hex
digest strings — **UPPERCASE for sha1, lowercase for sha256** (the
hashlookup convention). Any DCSO-compatible reader works.

Membership answers are probabilistic: p = 1e-4 false-positive rate,
no false negatives. Confirm anything important against the source.