C++ Seeding Surprises (2015)

10 months ago

C++11's std::seed_seq is intended to improve random number generator seeding but has limitations.
Using a single 32-bit integer to seed a large state RNG like Mersenne Twister leads to predictability and bias issues.
std::seed_seq can introduce bias even when provided with sufficient seed data, as it's not a bijection.
Initializing RNGs with insufficient seed data can result in missing or duplicated outputs, causing systemic bias.
The Mersenne Twister requires 19937 bits of seed data for unbiased initialization, making smaller seeds problematic.
std::seed_seq's design forces its use even when unnecessary, complicating proper seeding with std::random_device.
Proposed fixes include relaxing Seed Sequence requirements and adding a generate method to std::random_device.

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