Please write down or memorize these 12 words (their order and capitalization matters - always lowercase). This passphrase is needed in order to access your Nxt account.

There has been some talk about the danger of brain wallets in general. I've been wondering, if 12 random words, as generated by the nxt wallet is actually enough to be safe and secure?

What if in the future there is a botnet that tries attacking the nxt network to crack into people's wallet's ?

12 word passphrases are secure, I have personally audited the code and done the math and they are secure.

They use the javascript secure random number generator to product the necessary entropy, and selects words from a wordlist of 1626 different words, this gives us 1626^12 possible combinations and an entropy level of

Log (1626^12)/log (2) = 128 bits of entropy

This is an arbitrarily large number, with 38 decimal places, even with one trillion guesses a second, it would take until beyond the heat death of the universe to compute the entire keyspace.

I would not worry about the 12 word seed, the bigger issue is quantum computers breaking elliptic curve cryptography, but that won't be for another 15 or so years