Manifest and signature

Feed files are public, so anyone who can change what a URL serves could change your WAF. Two checks stop that: each file’s SHA-256 is in manifest.json, and manifest.json is signed.

manifest.json

{
  "feedUuid": "…",
  "orgUuid": "…",
  "name": "prod edge",
  "feedType": "SURICATA",
  "schemaVersion": 1,
  "generatedAt": 1793577600000,
  "files": [
    {
      "ruleType": "SURICATA",
      "filename": "suricata.rules",
      "url": "https://vulnetix.com/feeds/<org-uuid>/<feed-uuid>/suricata.rules",
      "sha256": "…",
      "ruleCount": 12
    },
    {
      "ruleType": "",
      "filename": "rules.json",
      "url": "https://vulnetix.com/feeds/<org-uuid>/<feed-uuid>/rules.json",
      "sha256": "…",
      "ruleCount": 12
    }
  ]
}

generatedAt is Unix milliseconds. rules.json is listed like any other file, so the signature covers it.

manifest.json.sig

The base64 of an Ed25519 signature over the exact bytes of manifest.json. Vulnetix signs every publish when its signing key is configured. A feed published without it has no .sig file.

The public key is a base64 string of the raw 32 bytes. Release builds of vulnetix-sensor have it pinned, so the sensor verifies without being told. Pass --feed-key (or set VULNETIX_FEED_KEY) only to override it, for example during a key rotation.

Verify by hand

With OpenSSL 3:

FEED="https://vulnetix.com/feeds/<org-uuid>/<feed-uuid>"
KEY="<base64 Ed25519 public key>"

curl -fsSLO "$FEED/manifest.json"
curl -fsSL "$FEED/manifest.json.sig" | base64 -d > manifest.sig

# Wrap the raw key in the Ed25519 SubjectPublicKeyInfo header.
{ printf '302a300506032b6570032100' | xxd -r -p; printf '%s' "$KEY" | base64 -d; } > feed-key.der
openssl pkey -pubin -inform DER -in feed-key.der -out feed-key.pem

openssl pkeyutl -verify -pubin -inkey feed-key.pem -rawin \
    -in manifest.json -sigfile manifest.sig
# Signature Verified Successfully

# Then check each file against the signed manifest.
curl -fsSLO "$FEED/suricata.rules"
jq -r '.files[] | select(.filename=="suricata.rules") | .sha256 + "  suricata.rules"' manifest.json \
    | sha256sum -c -

The <file>.sha256 beside each file is a convenience for scripts that do not check the signature. It is not signed, so it proves the download is intact, not that it came from Vulnetix.

What the sensor does with each case

Case	Result
Signature checks against the key	Rules may block, in the modes that allow it
No .sig, bad base64, or a signature that does not match	Feed loads as unverified: every rule reports and never blocks
No key configured at all	Same as unverified
A file whose SHA-256 does not match the manifest	The feed is refused outright, signed or not
manifest.json unchanged since the last fetch (same ETag)	Nothing is reloaded

vulnetix-sensor tetragon-policy is stricter: it refuses to run without a key, because the policy it renders blocks in the kernel.