BTW, how is the entropy of the password calculated?
Well since each word is random and there are 7776 possible outcomes that means each word has Log(7776) = 12.925 bits of entropy each. The entropy of the password would be # of words * entropy of each word.
5 words = ~64 bits
6 words = ~78 bits
7 words = ~90 bits
8 words = ~102 bits
9 words = ~116 bits
10 words = ~130 bits
I see. Thanks for your help.
I now finally understand why Electrum seed is just 128 bits when it has 12 words, it is simply because log1626/log 2*12 = 128.005
A seed is encoded with 12 words from a 1626 words dictionary.