What makes a good hash function?
It depends on the use case. Cryptography should minimize collisions, message digests should maximize hash differences on minor input differences, and bloom filters should do the reverse.
How can you estimate the suitability of a hash function for a particular task?
By using plots and tests to get a sense of how the output hashes are distributed and whether that's what you're looking for. Histograms and scatter plots work well to see the distribution of values. Also, search the internet for potential breaches or weaknesses and the original paper.
Is a checksum hash useful in other ways?
They can also be useful to determine whether two texts or files are equal, which can be used for finding matches quickly or to check whether the content is the content that was transferred or whether the content has been tampered with.
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