# Tag Info

### Password cracking: What if attacker is lucky?

"lucky" is not a property of the attacker. There's no "lucky" attacker nor "normal" attacker. They both have the same probability (low, very low) to guess the key. You can decrease the probability at ...

### Password cracking: What if attacker is lucky?

Note: This answer assumes that by "lucky" OP meant "able to remove X% of valid answers", because I believe that was intent. Of course you can't measure luck ;) And if he is very lucky, say 90% ...
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### Can Shannon's entropy be used to determine if a file is encrypted?

You are likely going to have both false positives and false negatives if you try to use Shannon entropy for this. Many compressed files would have close to 8 bits of entropy per byte, resulting in ...
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### A website that identifies an RNG from its output

A colleague of mine told me about a website that, given a sufficient quantity of output from an PRNG, had been able to deduce which application the PRNG was from. As you correctly identified this ...
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### A website that identifies an RNG from its output

One tool that tries to do this is untwister. It's almost certainly not the tool you were thinking of, though, as it cannot determine if the output came from OpenSSL specifically. It can determine ...
Accepted

### Password cracking: What if attacker is lucky?

So if at each bit he has a 50% chance, that means that 1 bit is actually only half bit. And if he is very lucky, say 90% chance, that means that 1 bit is actually only 0.1 bit.So in face of a very ...
• 374
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• 48.6k
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### Consuming of entropy

Why generating random consumes an entropy? For the same reason that to generate true random bits using coin throws, one needs to throw a coin for each bit generated. Any attempt to use less throws is ...
• 142k
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### How to analyze the off-by-one error's impact on the entropy of the result?

First of all the first Entropy calculation is not correct. Recall the definition of (Shannon) entropy: $$H(X) = -\sum_{i=1}^n {\mathrm{P}(x_i) \log_{\,b} \mathrm{P}(x_i)}$$ If uniformly chosen a ...
• 49k
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### Practical sources of entropy on an Android device?

Just use SecureRandom and let the OS take care of it.
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### Password cracking: What if attacker is lucky?

So if at each bit he has a 50% chance, that means that 1 bit is actually only half bit. No, it is not. Because 'bit' is a quantity of information we should know to reduce entropy twice by definition. ...
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