Commit aeb0db6f authored by 127.0.0.1's avatar 127.0.0.1 Committed by amnesia
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Fix wording

parent 410bcb38
......@@ -551,7 +551,7 @@ To determine whether data seems to be encrypted or random, we use [Pearson's chi
When trying to determine whether a *partition* (or whole device) is a VeraCrypt/TrueCrypt volume, we don't want to read more than necessary, to avoid slowing things down too much. Because non-encrypted filesystems usually start with a header, which is very non-random, we only perform the chi-squared test on these first 512 Bytes.
The chi-squared test requires a p-value, for which to reject the hypothesis that the data is random. We choose 1/10.000.000.000 as the p-value, which means that in one of 10 billion cases, the test will issue a false negative, i.e. that the data is non-random/non-encrypted even though it actually is random/encrypted. From this p-value, we derive the following lower and upper limits for the chi-squared value (using the [scipy chi2 module](https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.chi2.html)):
The chi-squared test requires a p-value, for which to reject the hypothesis that the data is random. We choose 1/10.000.000.000 as the p-value, which means that in one of 10 billion cases, the test will issue a false negative, i.e. the test says the data is non-random/non-encrypted, even though it actually is random/encrypted. From this p-value, we derive the following lower and upper limits for the chi-squared value (using the [scipy chi2 module](https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.chi2.html)):
>>> from scipy.stats import chi2
>>> chi2.ppf([0.1**10, 1-0.1**10], 255)
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