signal.org
HTTPS & TLS
88/100A- HSTS0/4
No HSTS: a visitor's first request can be downgraded to plain HTTP.
- HTTPS certificateGoogle Trust Services10/10
HTTPS with a valid certificate from Google Trust Services.
- Certificate expiry504/4
The certificate is valid for another 50 days.
- TLS versionTLS 1.34/4
Negotiates TLS 1.3, the current protocol: faster handshakes, forward secrecy always.
- Old protocols3/3
Refuses the retired TLS 1.0 and 1.1.
- Key strengthECDSA P-2562/2
A strong key: ECDSA P-256.
- HTTP → HTTPS3013/3
http:// redirects straight to https://.
- HTTP/2 and HTTP/3HTTP/32/2
HTTP/2 and HTTP/3.
DNS
86/100A- CAA records0/2
No CAA records: any certificate authority may issue certificates for the domain.
- Name servers24/4
2 name servers for the domain.
- Name servers answer2/25/5
Every name server answers for the domain, with the same version of the zone.
- DNSSECECDSAP256SHA2563/3
Signed with DNSSEC: resolvers can tell forged answers from real ones.
- SPF~all4/5
SPF lists the servers allowed to send its mail and marks the rest as suspicious (~all).
- DMARCquarantine5/7
DMARC sends mail that fakes the domain to spam (p=quarantine).
- MTA-STSenforce2/2
MTA-STS makes senders deliver mail to it only over verified TLS.
- TLS reporting0.5/0.5
TLS reporting: senders report failed encrypted deliveries.
- DKIMgoogle2/2
A DKIM key is published (selector google), so its mail can be signed.
Web & network
47/100F- Content Security Policy0/3
No Content Security Policy: an injected script runs with the page's full rights.
- Framing0/2
Any site can show its pages in a frame, which enables clickjacking.
- Permissions-Policy0/0.5
No Permissions-Policy: embedded content may ask for camera, microphone or location.
- RPKIunknown1/4
The route to the website is not covered by RPKI, so a hijack of it cannot be told apart.
- X-Content-Type-Options2/2
X-Content-Type-Options: nosniff stops browsers guessing file types.
- Referrer-Policystrict-origin-when-cross-origin0.5/0.5
Referrer-Policy limits what other sites learn about where visitors came from.
- IPv64/4
signal.org is reachable over IPv6 as well as IPv4.
Dependencies
60/100D- DNS providersCloudflare3/5
All DNS is with one provider (Cloudflare): an outage there takes the domain offline, as Dyn's did in 2016.
- One company for everythingCloudflare: website, DNS3/5
Cloudflare runs both the website and the DNS: one outage there takes both down.
Who runs it
- Website
- Cloudflare
- DNS
- Cloudflare
- Google Workspace
Routes
- 8.47.69.0/24AS13335RPKI unknown
- 2a06:98c1:3122::/48AS13335RPKI valid
Name servers
- casey.ns.cloudflare.comCloudflareAS13335
- zita.ns.cloudflare.comCloudflareAS13335
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What is graded
A valid certificate (an invalid one means F), its expiry against its lifetime, TLS 1.3, no TLS 1.0/1.1 (else at most B), http:// sent straight to https://, HSTS, HTTP/2.
At least two name servers that all answer and agree, DNSSEC, CAA records, and a registration that is not about to expire.
SPF, a DMARC policy that rejects forgeries (none means at most B), MTA-STS and TLS reporting for domains that take mail, DKIM at common selectors.
Content Security Policy, nosniff, framing protection, Referrer- and Permissions-Policy, IPv6, and an RPKI-valid route (invalid means at most C).
DNS from more than one provider, and the website, DNS and email not all with one company.
A+ 95–100 · A 85–94 · B 75–84 · C 65–74 · D 50–64 · F below 50