6 ms·
That's not true. Given a dictionary of 2048 words that the attacker has complete knowledge about, picking any 4 random words will always give you 44 bits of ent
by throwaway125 13y ago
That's not true. Given a dictionary of 2048 words that the attacker has complete knowledge about, picking any 4 random words will always give you 44 bits of entropy.
2048^4 = 17592186044416
2^44 = 17592186044416
- pfortuny 13y agoYes but grammatically correct sequences of words have much less entropy than that. I guess much much less.
- sp332 13y agoAs a rule of thumb, English text has about one bit per character of entropy. [0, 1] Since we're going with averages, let's say 5 letters + a space for each word. So you need a 7- or 8-word sentence, with normal capitalization and punctuation, to get 42 bits of entropy. And of course it shouldn't be a well-known phrase like "I've got a bad feeling about this!" [0] The original http://www.princeton.edu/~wbialek/rome/refs/shannon_51.pdf http://www.princeton.edu/~wbialek/rome/refs/shannon_51.pdf [1] and some evidence that it's still correct http://en.wikipedia.org/wiki/Hutter_Prize http://en.wikipedia.org/wiki/Hutter_Prize
- pfortuny 13y agoThanks, great info.