Un canari judiciaire est une déclaration publiée régulièrement et signée PGP attestant qu'un prestataire n'a pas reçu certains types de procédure judiciaire — le plus souvent une National Security Letter, une ordonnance de silence ou une demande de surveillance de masse. Le canari continue jusqu'à ce qu'il s'arrête. L'absence du prochain canari prévu est le signal que quelque chose a changé. Cette page explique le mécanisme, détaille la vérification PGP et liste les prestataires qui en maintiennent un en 2026.
Mis à jour · Auteur : Ingénierie Cryptoservers
The warrant canary depends on a specific asymmetry in compelled-speech doctrine. Many surveillance statutes — 18 USC §2709 in the United States (the National Security Letter authority); analogous provisions in the UK Investigatory Powers Act 2016 (§133 non-disclosure); equivalents in other 14-Eyes jurisdictions — include non-disclosure clauses that prevent the recipient of an order from talking about it. Those clauses compel silence. Dans la plupart des juridictions, elles n'obligent pas le destinataire à formuler activement une déclaration affirmative fausse.
That distinction is what the canary exploits. A provider publishes "we have not received an NSL as of [date]" on a fixed cadence — weekly, monthly, quarterly. As long as the statement remains true, publication continues. If the provider receives an order, they cannot say so directly (gag order). But they can stop publishing the affirmative statement. The next scheduled canary either does not appear, or appears with the relevant clause removed, or appears with different language. That absence — that change — is information that the gag order cannot suppress.
The Cryptoservers canary, published at /canary/, follows this pattern. Every Monday we re-sign a statement covering the week ending the prior Sunday. The signed statement enumerates: NSLs received (target: zero), gag orders received (target: zero), bulk-retention orders received (target: zero), per-jurisdiction order counts (Saint Kitts and Nevis, Iceland, Netherlands, Romania, Switzerland), DMCA notices received versus actioned, and abuse complaints received versus actioned. Five of the six numbers are expected to be zero in a normal week; the abuse and DMCA numbers are non-zero by design (we receive abuse complaints, and we publish how many).
The cadence matters. A canary published once a year carries less signal than one published weekly — the lag between coercion and the customer noticing is the freshness window. Weekly canaries reduce that window to seven days; daily canaries (rare, because they require key-handling at scale) reduce it to twenty-four hours. Quarterly canaries leave a three-month window in which a provider could be compromised before any external observer notices.
A canary that is not cryptographically signed is theatre. Verification takes four steps and about ninety seconds. The example below uses the Cryptoservers canary; the same procedure works for any provider that publishes a PGP-signed canary.
Étape 1 — Obtenir la clé publique du prestataire. Cryptoservers publie la clé PGP publique à /pgp/. The key fingerprint is documented on multiple pages of the website (about, canary, pgp, footer) so a single-page tampering attempt is detectable. Cross-reference the fingerprint against multiple sources — archive.org snapshots, the Wayback Machine, third-party PGP keyservers — before you trust it.
curl -O https://cryptoservers.io/pgp/cryptoservers-pubkey.asc
gpg --show-keys cryptoservers-pubkey.ascÉtape 2 — Importer la clé. Importez dans votre trousseau GnuPG local. La clé reste dans votre magasin local — aucun téléversement requis, aucune confiance tierce nécessaire.
gpg --import cryptoservers-pubkey.ascÉtape 3 — Télécharger le texte du canari signé. The canary at /canary/ is rendered HTML, but the underlying signed file is also available as a clearsigned .asc — visible at the bottom of the canary page or directly via the storage path. For the purposes of this example, save it as canary.asc in your working directory.
curl -O https://cryptoservers.io/canary/latest.ascÉtape 4 — Vérifier la signature. Run gpg --verify against the .asc file. A "Good signature" line confirms two things: the canary was signed by the holder of the imported key, AND the canary text has not been altered since signing. A failed verification means the file has been modified, the signature is invalid, or the key does not match — treat the canary as untrusted and investigate further.
gpg --verify canary.asc
# expected:
# gpg: Good signature from "Cryptoservers Ltd. <[email protected]>"
# gpg: Primary key fingerprint: 4DCF 5D6D 10AF F2AA 47E2 070E A62A EDAF 647E E3E6If you have not used GnuPG before, install it first: `apt install gnupg2` on Debian-family Linux, `brew install gnupg` on macOS, or download GPG4Win on Windows. The verification step itself is the same on every platform.
Liste courte et vérifiable. Nous avons inclus des exemples historiques (Apple 2013–2014, Reddit 2014–2016) pour contexte — ils sont utiles comme études de cas sur la façon dont un canari signale un changement. Envoyez-nous des ajouts via /contact/ si vous maintenez un canari public non listé ici.
| Prestataire / projet | Cadence | Première publication | Statut | Notes |
|---|---|---|---|---|
| rsync.net | Quarterly, PGP-signed | 2014 | Maintained | One of the earliest commercial canaries. Includes Bitcoin block-hash as a freshness anchor. |
| Cryptoservers | Weekly, PGP-signed (every Monday) | 2024 | Maintained | Per-jurisdiction order counts (KN, IS, NL, RO, CH) plus DMCA, abuse, NSL and gag-order statements. |
| Bahnhof (transparency report) | Annual transparency report (not a canary in the strict sense) | 2014 | Active transparency reporting | Swedish ISP. Publishes detailed transparency stats; the canary-style attestations are scattered through the integrity page rather than a single signed document. |
| The Tor Project | Annual | 2014 | Maintained | Re-affirmed annually. One of the longest-running organisational canaries. |
| Apple (historical) | Removed in 2014 — historical example, not current | 2013 | Removed (2014) — historical | Apple's November 2013 transparency report contained the canonical "Apple has never received an order under Section 215" canary statement. The line was conspicuously absent from the September 2014 report. Apple has not commented publicly on the change. |
| Reddit (historical) | Removed in 2016 — historical example, not current | 2014 | Removed (2016) — historical | Reddit's 2014 transparency report carried a National Security Letter canary. The 2015 report removed the language. The administrator who maintained the canary commented publicly that he could not say more. |
We deliberately keep this list short. A long aspirational list dilutes the signal — the value of a canary is that it is verifiable, and verification at scale is expensive. We update the list when we change it; the dateModified field on this page reflects the most recent verification pass.
Honest answer: less than the marketing copy implies. The dominant cause of a missed canary in the past decade has not been the receipt of a National Security Letter — it has been administrative oversight. The engineer responsible was on vacation, the cron job hit a credential rotation, the DNS for the canary subdomain expired, the company forgot. A single missed renewal is faible signal au mieux.
Ce qui transforme un signal faible en signal fort, c'est la corroboration. Cherchez :
Apple's 2014 canary removal is the canonical case study. The September 2013 transparency report contained the line "Apple has never received an order under Section 215 of the USA Patriot Act." The September 2014 transparency report did not. Apple issued no public statement explaining the change. Privacy researchers (Christopher Soghoian, then with the ACLU; Glenn Greenwald at The Intercept) flagged the absence within days. The signal was weak at first — could have been an editorial change — but the absence persisted across subsequent reports, and Apple's general counsel did not subsequently re-affirm the canary statement when directly asked. Two years later the consensus interpretation in the privacy-research community was that Apple had received a Section 215 order. Apple has never confirmed or denied this.
La bonne interprétation d'un canari manqué est « enquêter davantage », non « le fournisseur a été assigné ». Les canaris sont des indices en l'absence de tromperie, non des preuves en sa présence.
Trois limites honnêtes que vous devez peser avant de traiter un canari comme une preuve cryptographique de l'intégrité du fournisseur.
1. La théorie juridique repose sur une faille. The canary exploits a doctrine that gag orders compel silence rather than affirmative falsehood. That doctrine has not been definitively tested for every surveillance statute in every jurisdiction. The Stanford Law Review and other legal scholars have argued both sides. A determined prosecutor could plausibly argue that compelling continued affirmative publication of "we have not received" is itself part of a non-disclosure obligation, and that ceasing publication is a breach of the gag. The legal theory has held up so far in published US case law, but it has not been litigated to definitive resolution. Other jurisdictions are even less tested.
2. Les canaris non signés sont inutiles. A canary that is not signed with a verifiable PGP key — or that uses a key whose fingerprint cannot be cross-referenced against multiple independent sources — is theatre. An adversary who controls the provider's website can substitute a forged "everything is fine" canary and there is no way to detect the substitution. The PGP signature is what makes the canary load-bearing. Unsigned text is not a canary, no matter what it says. Verify before you trust.
3. Les canaris expirés sont ambigus. When a canary stops being renewed, the interpretation depends on what else is happening. A lapsed canary plus organisational silence plus a key change is strong signal. A lapsed canary alone is weak — it could mean the engineer is on vacation. A canary that never started is no signal at all. The burden of disambiguation falls on the customer; the provider can only honestly publish what they can honestly publish.
Treat canaries as one cultural-integrity signal among several, not as a security guarantee. A canary tells you that a provider thinks coercion is a real enough risk to invest engineering effort in pre-publishing the contradiction signal. That is meaningful. It is not the same thing as cryptographic proof.
Cryptoservers resigne le canari chaque lundi. La déclaration actuelle, l'archive de chaque semaine précédente et la clé PGP de vérification sont toutes sur /canary/.