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Master's Dissertation
DOI
10.11606/D.3.2016.tde-29062016-085500
Document
Author
Full name
Leonardo de Campos Almeida
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2016
Supervisor
Committee
Simplicio Junior, Marcos Antonio (President)
Goya, Denise Hideko
Ruggiero, Wilson Vicente
Title in Portuguese
Lyra: uma função de derivação de chaves com custos de memória e processamento configuráveis.
Keywords in Portuguese
Criptologia
Derivação de chaves
Esponjas criptográficas
Memória RAM
Segurança de redes
Utilização de memória
Abstract in Portuguese
Este documento apresenta o Lyra, um novo esquema de derivação de chaves, baseado em esponjas criptográficas. O Lyra foi projetado para ser estritamente sequencial, fornecendo um nível elevado de segurança mesmo contra atacantes que utilizem múltiplos núcleos de processamento, como uma GPU ou FPGA. Ao mesmo tempo possui uma implementação simples em software e permite ao usuário legítimo ajustar o uso de memória e tempo de processamento de acordo com o nível de segurança desejado. O Lyra é, então, comparado ao scrypt, mostrando que esta proposta fornece um nível se segurança mais alto, além de superar suas deficiências. Caso o atacante deseje realizar um ataque utilizando pouca memória, o tempo de processamento do Lyra cresce exponencialmente, enquanto no scrypt este crescimento é apenas quadrático. Além disto, para o mesmo tempo de processamento, o Lyra permite uma utilização maior de memória, quando comparado ao scrypt, aumentando o custo de ataques de força bruta.
Title in English
Lyra: password-based key derivation with tunable memory and processing costs.
Keywords in English
Cryptographic sponges
Memory usage
Password-based key derivation
Security
Abstract in English
This document presents Lyra, a password-based key derivation scheme based on cryptographic sponges. Lyra was designed to be strictly sequential, providing strong security even against attackers that use multiple processing cores, such as FPGAs or GPUs. At the same time, it is very simple to implement in software and allows legitimate users to tune its memory and processing costs according to the desired level of security. We compare Lyra with scrypt, showing how this proposal provides a higher security level and overcomes limitations of scrypt. If the attacker wishes to perform a low-memory attack against the algorithm, the processing cost grwos expontetialy, while in scrypt, this growth is only quadratic. In addition, for an identical processing time, Lyra allows for a higher memory usage than its counterparts, further increasing the cost of brute force attacks.
 
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Publishing Date
2016-06-29
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • ALMEIDA, L. C., et al. Lyra: Password-Based Key Derivation with Tunable Memory and Processing Costs. Journal of Cryptographic Engineering, 2014.
All rights of the thesis/dissertation are from the authors
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