Question

For a demo project, I want to create a hashing function with a very high probability of collision. Something simple is fine since the aim of the project is NOT security – but to demonstrate hash collisions.

Can anyone help me get started with an algorithm, or a sample implementation, or just point me in the right direction?

I am doing this in Python, though maybe that should not matter.

Answer 1

You could use the sum of the characters in a string. It’s the first hash function I was taught back when I was first learning BASIC in high school, and I ran into the collision problem right away and had to figure out how to deal with it.

sum(ord(c) for c in text)

Transpositions are easily achieved by swapping strings or even words. For more fun you could also make it case-insensitive:

sum(ord(c) for c in text.lower())

I’ll even give you a sample collision for that last one: Jerry Kindall -> Dillan Kyrjer 🙂