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PwnFunction/v8-randomness-predictor

Using z3 to predict `Math.random` in v8
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v8-randomness-predictor

Using z3 to predict Math.random in v8

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Run Instructions

Get a few Random numbers from v8, run to following code in d8, nodejs or chrome.

Array.from(Array(5), Math.random)

Optionally you can set the random seed in nodejs so you'd get the same numbers as shown below.

/*
* Run nodejs with `--random_seed` flag like
* node --random_seed=1337
*/
Array.from(Array(5), Math.random)
// [0.9311600617849973, 0.3551442693830502, 0.7923158995678377, 0.787777942408997, 0.376372264303491]

Next we feed these random numbers into the python script (line 23).

sequence = [
  0.9311600617849973,
  0.3551442693830502,
  0.7923158995678377,
  0.787777942408997,
  0.376372264303491,
][::-1]

Run the script.

$ python3 main.py

# Outputs
# {'se_state1': 6942842836049070467, 'se_state0': 4268050313212552111}
# 0.23137147109312428

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