How is measured the entropy of a password in https://xkcd.com/936/ https://xkcd.com/936/ is a good hint on why this could be dangerous. Passwords should be stro

How is measured the entropy of a password in https://xkcd.com/936/ https://xkcd.com/936/ is a good hint on why this could be dangerous. Passwords should be strong even if you know/deduce how they are generated, specially if the input data is something as generic as the site domain. Trying intuitive/easy to perform algorithms could be a different kind of "dictionary" attack. How complicated look a password from the point of view of a brute force attack is not the only factor that make them safe for any kind of automated attack. Having a spreadsheet matching sites and algorithms may be another weak spot depending on how it is stored. Password managers usually keeps metadata about sites, not just the password, and it is stored encrypted.