[_ps6d]

I use a Bloom filter for this as well, but in Redis using the RedisBloom module. This was really easy to set up, but it does mean that it requires about 1GB of RAM or so (depending on error rate) dedicated to it, so it wouldn't be ideal if you're constrained for RAM.

I run a separate Redis server specifically for this purpose, which means when I want to update the list, I can build the Bloom filter on my local machine, and then just transfer the RDB file to the server and replace the previous one.

Here's the Python code for the simple CLI tool to initialize and add the hashes from the HIBP files to the Bloom filter if anyone's curious: https://gitlab.com/tildes/tildes/-/blob/master/tildes/script...

To check if a password's in the list, you just SHA-1 hash it and send a Redis command like:

    BF.EXISTS breached_passwords_bloom <sha1>