An Observation About Passphrases: Syntax vs Entropy

I suggested in the article to use passphrases instead of «traditional» passwords, for multiple reasons, including: sheer strength, memorability, and conforming to idiotic password creation policies without actually following detrimental recommendations of the policy authors.

This recommendation gives rise to a reasonable doubt: «what if syntactically correct phrases are as weak as dictionary words in comparison to a random string of symbols?''. Indeed, syntax itself should weaken a passphrase, as it provides some „predictability'' to the phrase. I want to address this problem, by comparing syntactically correct passphrases to random collections of words (which we all consider sufficiently strong… hopefully).
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