document: A large-scale study of web password habits We report the results of a large scale study of password use andpassword re-use habits . The study involved half a million users over athree month period . A client component on users ' machines recorded a variety of password strength , usage and frequency metrics . This allows us to measure or estimate such quantities as the average number of passwords and average number of accounts each user has , how many passwords she types per day , how often passwords are shared among sites , and how often they are forgotten . We get extremely detailed data on password strength , the types and lengths of passwords chosen , and how they vary by site . The data is the first large scale study of its kind , and yields numerous other insights into the role the passwords play in users ' online experience .
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