Quote from: Klestin on June 13, 2015, 01:31:23 PM

As to math problems, I'll only point out that there are nowhere near 1 million english words - there are less than 200k words in total.

Quick search has shown this:
"The number of words in the English language is: 1,025,109.8. This is the estimate by the Global Language Monitor on January 1, 2014." source
So the 1 million words is OK, however it is more realistic that an average person uses only a fraction of this, as you said as well. Above-average people may use something like 25'000 so that is the order you should be looking at, maybe even less, yes. These are the words you would normally think of. Unless, of course, you flip open some scientific magazines.

Let's jump to maths.

Quote from: Quickseller

if someone can find any non-trival errors in my math then please feel free to point them out

There are 1,000,0003, or ~1 * 1018 possibilities as to what your first (signing) address will be. If you can calculate a trillion 'three word' passphrase combinations per second then it would take you 1,000,000 seconds or ~99 weeks to find all of the possible 'three word' passphrase combinations - they have probably already been found a long time ago.

(1*10^18)/(1*10^12)=1000'000 which gives your 1 million seconds to break the first passphrase
1000'000/(60seconds*60minutes*24hours)=11.57 days instead of 99weeks

Assuming from the above an above-average person's dictionary, say 25'000 words, with the same numbers the first passphrase can be broken under 0.3 seconds.
The same 25'000 words, cracking with bitcoin network analogy would come down to under 20 years. Still probably pointless, but way less than the 3.3 trillion years. (which has probably the same flaw in calculating the time and it would be actually something like 0.08 trillion years, 7.93E10)

Check again the way you converted hashing time to actual time it takes and it will be OK. Significant error, however for the practical use it doesn't matter. If it takes 20,3 billion or 3 trillion years, who really cares? People will be happier stealing accounts with no encryption or the passphrase "puppy".

On a final note, I don't think you can make 10E12 guesses (trillion) per second, yet alone refurbish the Bitcoin network Wink

. You can use this method if you want, but don't come up with words on your own like "it is Friday". Open a science book or something similar and roll some dice. However, at this point I would ask why would I do this? I personally find this method way too complex to be of practical use to me. I can write down my password somewhere and hide it on a piece of paper in a book's cover, glued to the back of some furniture etc etc.