[Python-Dev] os.urandom API (original) (raw)

Raymond Hettinger raymond.hettinger at verizon.net
Sun Aug 29 22:37:17 CEST 2004

I would like to change the API for the new os.urandom(n) function to return a long integer instead of a string. The former better serves more use cases and fits better with existing modules.

In favor of a long integer:

  1. The call random.seed(os.random(100)) is a likely use case. If the intermediate value is a string, then random.seed() will hash it and only use 32 bits. If the intermediate value is a long integer, all bits are used. In the given example, the latter is clearly what the user expects (otherwise, they would only request 4 bytes).

  2. Another likely use case is accessing all the tools in the random module with a subclass that overrides random() and getrandbits(). Both can be done easier and faster if os.random() returns long integers. If the starting point is a string, the code gets ugly and slow.

  3. Most use cases for random values involve numeric manipulation. Simple tasks like finding a random integer in the range [0,100000) become unnecessarily more complicated when starting from a string.

  4. The decimal module supports instantiation directly from long integers but not from binary strings.

In favor of a string of bytes:

  1. This form is handy for cyptoweenies to xor with other byte strings (perhaps for a one-time pad).

Raymond

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