ed448
ed448 is the EdDSA signature scheme on Curve448. Only OpenSSL-based clients offer it in our measurements.
What it is
ed448 (code 0x0808) is the Edwards-curve Digital Signature Algorithm on Curve448, described in RFC 8032 and available in TLS 1.3 through RFC 8446. It is the larger sibling of ed25519, with about 224 bits of security, 57-byte public keys and 114-byte signatures.
Like ed25519 it is deterministic, so it does not depend on a good random number for each signature. Public certificate authorities do not issue Ed448 certificates, so on the public web it is almost never used; it appears in private PKI and in deployments that ask for security above 128 bits.
It pairs with the x448 key exchange, which uses the same curve in Montgomery form.
Because the client lists it, a server with an Ed448 certificate could use it, but such servers are almost never found on the public internet.
Who sends it
Measured on 2026-10-25 against our own test server: sent by 6 of 11 clients. Position counts from 1 and ignores GREASE values.
Why it matters for fingerprinting
Python requests, httpx, Node.js fetch, Guzzle and Debian curl, all built on OpenSSL, send it, while curl_cffi, curl-impersonate, macOS curl and Go net/http do not. Our Chrome capture did not record signature algorithms.
Debian curl sends it 5th, the other OpenSSL clients 8th. Go net/http offers ed25519 but not ed448, which is a small difference between Go and OpenSSL clients.
Check whether your client sends it
Open the test from your browser, or call it from your script, and look for ed448 in the TLS details.
Run the TLS fingerprint test