# Normalized Fingerprints

It is observed that Google Chrome has been shuffling their list of TLS Extensions for every ClientHello.
As a result, each new ClientHello created has a "unique" order of TLS Extensions and leads to a "unique" fingerprint, since our fingerprint calculation algorithm takes the order of extensions into account for good granularity.
Such shuffling feature has greatly reduced traceability for each individual fingerprints since the probability of the same order to be observed again is mathematically low.

For example, Google Chrome 109 has 18 TLS extensions, and 15 of them doesn't have a fixed position in the list. Assuming the order is truly uniformly randomized, the chance of the same fingerprint to be seen again is 1/(15!)=7.6471637e-13.

As an effort to keep this service working, we introduced fingerprints extension normalization, which sorts the list of extensions in a ClientHello and calculate the fingerprint based on the same ClientHello message with the list of extensions to be replaced with the sorted version. All normalized fingerprints start with an "N/", which stands for "Normalized". The order of the extensions might not be observed (yet) in the real world.