So I’ve run into this issue in the past but I finally started looking into why Python is soo slow at running basic math operations in a long loop, for example, simple stream cipher operations. You’ll see lots of suggestions to use numpy instead, however, I didn’t find this to be the most helpful. Since I like writing/reading C, I remembered that Python has a built-in ctypes module which is very helpful and useful if you are in need of specialized and optimized code paths. You can pretty easily pass in integer and byte array pointers with little complexity!

For example:

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