Published: February 24, 2020
Author(s)
John Kelsey (NIST), Dana Dachman-Soled (University of Maryland), Sweta Mishra (NIST), Meltem Sönmez Turan (NIST)
Conference
Name: RSA Conference 2020
Dates: February 24-28, 2020
Location: San Francisco, California, United States
Citation: Topics in Cryptology – CT-RSA 2020, Lecture Notes in Computer Science vol. 12006,
We introduce the notion of Ticket-Mediated Password Strengthening (TMPS), a technique for allowing users to derive keys from passwords while imposing a strict limit on the number of guesses of their password any attacker can make, and strongly protecting the users' privacy. We describe the security requirements of TMPS, and then a set of efficient and practical protocols to implement a TMPS scheme, requiring only hash functions, CCA2-secure encryption, and blind signatures. We provide several variant protocols, including an offline symmetric only protocol that uses a local trusted computing environment, and online variants that avoid the need for blind signatures in favor of group signatures or stronger trust assumptions. We formalize the security of our scheme by defining an ideal functionality in the Universal Composability (UC) framework, and by providing game-based definitions of security. We prove that our protocol realizes the ideal functionality in the random oracle model (ROM) under adaptive corruptions with erasures, and prove that security w.r.t. the ideal/real definition implies security w.r.t. the game-based definitions.
We introduce the notion of Ticket-Mediated Password Strengthening (TMPS), a technique for allowing users to derive keys from passwords while imposing a strict limit on the number of guesses of their password any attacker can make, and strongly protecting the users' privacy. We describe the security...
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We introduce the notion of Ticket-Mediated Password Strengthening (TMPS), a technique for allowing users to derive keys from passwords while imposing a strict limit on the number of guesses of their password any attacker can make, and strongly protecting the users' privacy. We describe the security requirements of TMPS, and then a set of efficient and practical protocols to implement a TMPS scheme, requiring only hash functions, CCA2-secure encryption, and blind signatures. We provide several variant protocols, including an offline symmetric only protocol that uses a local trusted computing environment, and online variants that avoid the need for blind signatures in favor of group signatures or stronger trust assumptions. We formalize the security of our scheme by defining an ideal functionality in the Universal Composability (UC) framework, and by providing game-based definitions of security. We prove that our protocol realizes the ideal functionality in the random oracle model (ROM) under adaptive corruptions with erasures, and prove that security w.r.t. the ideal/real definition implies security w.r.t. the game-based definitions.
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Keywords
dictionary attacks; TMPS; key derivation
Control Families
None selected