Launch HN: Blyss (YC W23) – Homomorphic encryption as a service

Private retrieval is a more general concept, which refers to retrieving data from a server without letting it learn your access pattern. In a specific application, it's easier to see the contrast: for example, in our password checker (https://playground.blyss.dev/passwords), the data that Blyss helps keep encrypted, and prevents the server from learning, is which password you are checking. With standard E2EE techniques, it would not really possible to keep your query private.

In messaging, Blyss can be used to build messaging services that not only do not learn what you say (the standard E2EE guarantee), but also do not learn who you talk to. We're working on this, but it's a tricky thing to ship.

Have you thought about making some ELI5 explainer on how the algo essentially works?

The post you link to is already a great start, I feel like it’s just a question of a little editing work and maybe more examples

— for the nerds to get interested and actually read the paper

— for the users to understand privacy properties better (eg why this is better than TLS in case of a server infected with malware, etc

— and also things which it doesn’t do, which would calm anxiety in those who /need/ to understand the limitations to feel safe

— and to keep devs from thinking it’s a magic pixie dust and over-promising users, only to get hacked

From a hardware perspective, NTT can be done in parallel, but has a fairly large working set of data (~512 MB) with lots of unstructured accesses. This is too big to fit in even the largest CPU L3 caches, so DRAM bandwidth is still relevant. It may be eventually be feasible to build an ASIC with this much on-chip memory, but in the meantime, GPUs do a pretty decent job with their massive HBM bandwidth.