mldsa44
mldsa44 is the ML-DSA-44 post-quantum signature scheme for TLS 1.3. curl_cffi and the OpenSSL-based Python, Node.js and PHP clients already offer it.
What it is
mldsa44 (code 0x0904) is the TLS 1.3 signature scheme for ML-DSA-44, the smallest parameter set of the Module-Lattice-Based Digital Signature Algorithm standardized by NIST as FIPS 204. Its use in TLS is described in the draft-ietf-tls-mldsa Internet-Draft, which adds mldsa44, mldsa65 and mldsa87.
ML-DSA is meant to resist attacks by future quantum computers, which would break RSA and ECDSA. The price is size: ML-DSA-44 public keys are 1,312 bytes and signatures 2,420 bytes, much larger than ECDSA, which makes certificate chains heavier.
Listing it only says that the client could verify such signatures. Public certificate authorities do not issue ML-DSA certificates yet, so on today's web the scheme is announced but not used.
Both client and server must support a scheme before it can be used, so listing it now prepares for certificates that do not exist yet.
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
curl_cffi sends it first in its list, and Python requests, httpx, Node.js fetch and Guzzle 3rd, all of them clients with a recent TLS library. Debian curl, macOS curl, both curl-impersonate profiles and Go net/http do not send it. Our Chrome capture did not record signature algorithms. Because support is new, the scheme helps date a client's TLS library.
Check whether your client sends it
Open the test from your browser, or call it from your script, and look for mldsa44 in the TLS details.
Run the TLS fingerprint test