Passwords and the evolution of imperfect authentication Page 1 78 COMMUNICATIONS OF
THE ACM | JULY 2015 | VOL. 58 | NO. 7 contributed articles DOI:10.1145/2699390 Theory on …

" It also provides a solid, up-to-date reference or self-study tutorial for system engineers,
programmers, system managers, network managers, product marketing personnel, system …

Modern password guessing attacks adopt sophisticated probabilistic techniques that allow
for orders of magnitude less guesses to succeed compared to brute force. Unfortunately …

Smartphones today store large amounts of data that can be confidential, private or sensitive.
To protect such data, all mobile OSs have a phone lock mechanism, a mechanism that …

Passwords are ubiquitous in our daily digital lives. They protect various types of assets
ranging from a simple account on an online newspaper website to our health information on …

While much has changed in Internet security over the past decades, textual passwords
remain as the dominant method to secure user web accounts and they are proliferating in …

Many security policies force users to change passwords within fixed intervals, with the
apparent justification that this improves overall security. However, the implied security …

BACKGROUND 0003 Advances in mobile computing and hardware plat forms have
enabled mobile devices to become extensions of their users. The category of mobile devices …

To ensure that users do not choose weak personal identication numbers (PINs), many banks
give out system-generated random PINs. 4-digit is the most commonly used PIN length, but …

To solve the long-standing problems users have in creating and remembering text
passwords, a wide variety of alternative authentication schemes have been proposed. Some …