Cryptographic Hash Functions in Groups and Provable Properties
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An Advance Visual Model for Animating Behavior of Cryptographic Protocols
An Advance Visual Model for Animating Behavior of Cryptographic Protocols Mabroka Ali Mayouf Maeref1*, Fatma Alghali2, Khadija Abied2 1 Sebha University, Faculty of Science, Department of Computer Science, P. O. Box 18758 Sebha, Libya, Libyan. 2 Sebha University of Libya, Sebha, Libya. * Corresponding author. Tel.: 00218-925132935; email: [email protected] Manuscript submitted February 13, 2015; accepted July 5, 2015. doi: 10.17706/jcp.10.5.336-346 Abstract: Visual form description benefits from the ability of visualization to provide precise and clear description of object behavior especially if the visual form is extracted from the real world. It provides clear definition of object and the behavior of that object. Although the current descriptions of cryptographic protocol components and operations use a different visual representation, the cryptographic protocols behaviors are not actually reflected. This characteristic is required and included within our proposed visual model. The model uses visual form and scenario-based approach for describing cryptographic protocol behavior and thus increasing the ability to describe more complicated protocol in a simple and easy way. Key words: Animation, cryptographic protocols, interactive tool, visualization. 1. Introduction Cryptographic protocols (CPs) mostly combine both theory and practice [1], [2]. These cause protocol complexity describing and understanding. Therefore, separating the mathematical part from the protocol behavior should provide feeling of how the protocol works, thus increasing the ability to describe and to gain confidence in reflecting more complicated information about CPs, as well as to generate interest to know about other more complex protocol concepts. Several researchers realized the use of visual model and animation techniques to reflect the explanation of the learning objectives and their benefits [3]-[11]. -
(1) Hash Functions (2) MAC MDC OWHF CRHF UOWHF
Hash functions (1) are secure; they can be reduced to @ @ 2 classes based on linear transfor- @ @ mations of variables. The properties @ of these 12 schemes with respect to @ @ Hash Functions: Past, Present and Future weaknesses of the underlying block @ @ cipher are studied. The same ap- proach can be extended to study keyed hash functions (MACs) based - -63102392168 on block ciphers and hash functions h Bart Preneel based on modular arithmetic. Fi- nally a new attack is presented on a scheme suggested by R. Merkle. Katholieke Universiteit Leuven This slide is now shown at the Asi- acrypt 2005 in the beautiful city of bartDOTpreneel(AT)esatDOTkuleuvenDOTbe Chennai during a presentation on the state of hash functions. http://homes.esat.kuleuven.be/ preneel ∼ 5 December 2005 3 Outline Hash functions (2) Definitions • cryptographic hash function Z Z Applications Z Z • Z Z General Attacks = ZZ~ • MAC MDC Constructions @ @ • @ @ Custom Designed Hash Functions @ • © @R Hash Functions Based on Block Ciphers OWHF ? CRHF • Hash Functions Based on Algebraic Operations UOWHF • Pseudo-randomness • This talk: only MDCs (Manipulation Detection Codes), which are Conclusions often called `hash functions' • 2 4 Informal definitions (1) Informal definitions (3) preimage resistant 2nd preimage resistant 6) take a preimage resistant hash function; add an input bit b and • replace one input bit by the sum modulo 2 of this input bit and b 2nd preimage resistant preimage resistant 6) if h is OWHF, h is 2nd preimage resistant but not preimage • resistant -
A Matter of Security, Privacy and Trust
A matter of security, privacy and trust: A study of the principles and values of encryption in New Zealand Michael Dizon Ryan Ko Wayne Rumbles Patricia Gonzalez Philip McHugh Anthony Meehan Acknowledgements This study was funded by grants from the New Zealand Law Foundation and the University of Waikato. We would like to express our gratitude to our project collaborators and members of the Advisory Board – Prof Bert-Jaap Koops (Tilburg University), Prof Lyria Bennett Moses (UNSW Sydney), Prof Alana Maurushat (Western Sydney University), and Associate Professor Alex Sims (University of Auckland) – for their support as well as feedback on specific parts of this report. We would also like to thank Patricia Gonzalez, Joseph Graddy, Philip McHugh, Anthony Meehan, Jean Murray and Peter Upson for their valuable research assistance and other contributions to this study. Michael Dizon, Ryan Ko and Wayne Rumbles Principal investigators December 2019 Executive summary Cybersecurity is crucial for ensuring the safety and well-being of the general public, businesses, government, and the country as a whole. New Zealand has a reasonably comprehensive and well-grounded legal regime and strategy for dealing with cybersecurity matters. However, there is one area that deserves further attention and discussion – encryption. Encryption is at the heart of and underpins many of the technologies and technical processes used for computer and network security, but current laws and policies do not expressly cover this significant technology. The principal objective of this study is to identify the principles and values of encryption in New Zealand with a view to informing future developments of encryption- related laws and policies. -
Security of VSH in the Real World
Security of VSH in the Real World Markku-Juhani O. Saarinen Information Security Group Royal Holloway, University of London Egham, Surrey TW20 0EX, UK. [email protected] Abstract. In Eurocrypt 2006, Contini, Lenstra, and Steinfeld proposed a new hash function primitive, VSH, very smooth hash. In this brief paper we offer com- mentary on the resistance of VSH against some standard cryptanalytic attacks, in- cluding preimage attacks and collision search for a truncated VSH. Although the authors of VSH claim only collision resistance, we show why one must be very careful when using VSH in cryptographic engineering, where additional security properties are often required. 1 Introduction Many existing cryptographic hash functions were originally designed to be message di- gests for use in digital signature schemes. However, they are also often used as building blocks for other cryptographic primitives, such as pseudorandom number generators (PRNGs), message authentication codes, password security schemes, and for deriving keying material in cryptographic protocols such as SSL, TLS, and IPSec. These applications may use truncated versions of the hashes with an implicit as- sumption that the security of such a variant against attacks is directly proportional to the amount of entropy (bits) used from the hash result. An example of this is the HMAC−n construction in IPSec [1]. Some signature schemes also use truncated hashes. Hence we are driven to the following slightly nonstandard definition of security goals for a hash function usable in practice: 1. Preimage resistance. For essentially all pre-specified outputs X, it is difficult to find a message Y such that H(Y ) = X. -
Analysis and Implementation of the Messaging Layer Security Protocol
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by AMS Tesi di Laurea Alma Mater Studiorum · Universita` di Bologna CAMPUS DI CESENA Dipartimento di Informatica - Scienza e Ingegneria Corso di Laurea Magistrale in Ingegneria e Scienze Informatiche Analysis and Implementation of the Messaging Layer Security Protocol Tesi in Sicurezza delle Reti Relatore: Presentata da: Gabriele D'Angelo Nicola Giancecchi Anno Accademico 2018/2019 Parole chiave Network Security Messaging MLS Protocol Ratchet Trees \Oh me, oh vita! Domande come queste mi perseguitano. Infiniti cortei d'infedeli, citt`agremite di stolti, che v'`edi nuovo in tutto questo, oh me, oh vita! Risposta: Che tu sei qui, che la vita esiste e l’identit`a. Che il potente spettacolo continua, e che tu puoi contribuire con un verso." - Walt Whitman Alla mia famiglia. Introduzione L'utilizzo di servizi di messaggistica su smartphone `eincrementato in maniera considerevole negli ultimi anni, complice la sempre maggiore disponi- bilit`adi dispositivi mobile e l'evoluzione delle tecnologie di comunicazione via Internet, fattori che hanno di fatto soppiantato l'uso dei classici SMS. Tale incremento ha riguardato anche l'utilizzo in ambito business, un contesto dove `epi`ufrequente lo scambio di informazioni confidenziali e quindi la necessit`adi proteggere la comunicazione tra due o pi`upersone. Ci`onon solo per un punto di vista di sicurezza, ma anche di privacy personale. I maggiori player mondiali hanno risposto implementando misure di sicurezza all'interno dei propri servizi, quali ad esempio la crittografia end-to-end e regole sempre pi`ustringenti sul trattamento dei dati personali. -
The First Cryptographic Hash Workshop
Workshop Report The First Cryptographic Hash Workshop Gaithersburg, MD Oct. 31-Nov. 1, 2005 Report prepared by Shu-jen Chang and Morris Dworkin Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 Available online: http://csrc.nist.gov/groups/ST/hash/documents/HashWshop_2005_Report.pdf 1. Introduction On Oct. 31-Nov. 1, 2005, 180 members of the global cryptographic community gathered in Gaithersburg, MD to attend the first Cryptographic Hash Workshop. The workshop was organized in response to a recent attack on the NIST-approved Secure Hash Algorithm SHA-1. The purpose of the workshop was to discuss this attack, assess the status of other NIST-approved hash algorithms, and discuss possible near-and long-term options. 2. Workshop Program The workshop program consisted of two days of presentations of papers that were submitted to the workshop and panel discussion sessions that NIST organized. The main topics for the discussions included the SHA-1 and SHA-2 hash functions, future research of hash functions, and NIST’s strategy. The program is available at http://csrc.nist.gov/groups/ST/hash/first_workshop.html. This report only briefly summarizes the presentations, because the above web site for the program includes links to the speakers' slides and papers. The main ideas of the discussion sessions, however, are described in considerable detail; in fact, the panelists and attendees are often paraphrased very closely, to minimize misinterpretation. Their statements are not necessarily presented in the order that they occurred, in order to organize them according to NIST's questions for each session. 3. -
Implementaç˜Ao Em Software De Algoritmos De Resumo Criptográfico
Instituto de Computa¸c~ao Universidade Estadual de Campinas Implementa¸c~aoem software de algoritmos de resumo criptogr´afico Thomaz Eduardo de Figueiredo Oliveira i FICHA CATALOGRÁFICA ELABORADA PELA BIBLIOTECA DO IMECC DA UNICAMP Bibliotecária: Maria Fabiana Bezerra Müller – CRB8 / 6162 Oliveira, Thomaz Eduardo de Figueiredo OL4i Implementação em software de algoritmos de resumo criptográfico/Thomaz Eduardo de Figueiredo Oliveira-- Campinas, [S.P. : s.n.], 2011. Orientador : Julio César López Hernández. Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação. 1.Criptografia. 2.Hashing (Computação). 3.Arquitetura de computadores. I. López Hernández, Julio César. II. Universidade Estadual de Campinas. Instituto de Computação. III. Título. Título em inglês: Software implementation of cryptographic hash algorithms Palavras-chave em inglês (Keywords): Cryptography Hashing (Computer science) Computer architecture Área de concentração: Teoria da Computação Titulação: Mestre em Ciência da Computação Banca examinadora: Prof. Dr. Julio César López Hernández (IC – UNICAMP) Prof. Dr. Ricardo Dahab (IC – UNICAMP) Dr. José Antônio Carrijo Barbosa (CEPESC-ABIN) Data da defesa: 16/06/2011 Programa de Pós-Graduação: Mestrado em Ciência da Computação ii Instituto de Computa¸c~ao Universidade Estadual de Campinas Implementa¸c~aoem software de algoritmos de resumo criptogr´afico Thomaz Eduardo de Figueiredo Oliveira1 16 de junho de 2011 Banca Examinadora: • Prof. Dr. Julio C´esarL´opez Hern´andez IC/Universidade Estadual de Campinas (Orientador) • Prof. Dr. Ricardo Dahab IC/Universidade Estadual de Campinas • Dr. Jos´eAnt^onioCarrijo Barbosa CEPESC/Ag^enciaBrasileira de Intelig^encia • Prof. Dr. Paulo L´ıciode Geus (Suplente) IC/Universidade Estadual de Campinas • Prof. Dr. Routo Terada (Suplente) IME/Universidade de S~aoPaulo 1Suporte financeiro de: CNPq (processo 133033/2009-0) 2009{2011. -
Cryptography and Public Key Infrastructure on the Internet
Cryptography and Public Key Infrastructure on the Internet Klaus Schmeh Gesellsschaft für IT-Sicherheit AG Bochum, Germany Cryptography and Public Key Infrastructure on the Internet Cryptography and Public Key Infrastructure on the Internet Klaus Schmeh Gesellsschaft für IT-Sicherheit AG Bochum, Germany Copyright © 2001 by dpunkt.verlag GmbH, Heidelberg, Germany. Title of the German original: Kryptografie und Publik-Key-Infrastrukturen im Internet. ISBN: 3 932588 90 8 English translation Copyright 2003 by John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England. All rights reserved National 01243 779777 International (+44) 1243 779777 e-mail (for orders and customer service enquiries): [email protected] Visit our Home Page on http://www.wileyeurope.com or http://www.wiley.com All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the publication. Requests to the Publisher should be addressed to the Permissions Department, John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England, or emailed to [email protected], or faxed to (+44) 1243 770571. -
Analysis and Processing of Cryptographic Protocols
Analysis and Processing of Cryptographic Protocols Submitted in partial fulfilment of the requirements of the degree of Bachelor of Science (Honours) of Rhodes University Bradley Cowie Grahamstown, South Africa November 2009 Abstract The field of Information Security and the sub-field of Cryptographic Protocols are both vast and continually evolving fields. The use of cryptographic protocols as a means to provide security to web servers and services at the transport layer, by providing both en- cryption and authentication to data transfer, has become increasingly popular. However, it is noted that it is rather difficult to perform legitimate analysis, intrusion detection and debugging on data that has passed through a cryptographic protocol as it is encrypted. The aim of this thesis is to design a framework, named Project Bellerophon, that is capa- ble of decrypting traffic that has been encrypted by an arbitrary cryptographic protocol. Once the plain-text has been retrieved further analysis may take place. To aid in this an in depth investigation of the TLS protocol was undertaken. This pro- duced a detailed document considering the message structures and the related fields con- tained within these messages which are involved in the TLS handshake process. Detailed examples explaining the processes that are involved in obtaining and generating the var- ious cryptographic components were explored. A systems design was proposed, considering the role of each of the components required in order to produce an accurate decryption of traffic encrypted by a cryptographic protocol. Investigations into the accuracy and the efficiency of Project Bellerophon to decrypt specific test data were conducted. -
Design and Analysis of Hash Functions What Is a Hash Function?
Design and analysis of hash functions Coding and Crypto Course October 20, 2011 Benne de Weger, TU/e what is a hash function? • h : {0,1}* {0,1}n (general: h : S {{,}0,1}n for some set S) • input: bit string m of arbitrary length – length may be 0 – in practice a very large bound on the length is imposed, such as 264 (≈ 2.1 million TB) – input often called the message • output: bit string h(m) of fixed length n – e.g. n = 128, 160, 224, 256, 384, 512 – compression – output often called hash value, message digest, fingerprint • h(m) is easy to compute from m • no secret information, no key October 20, 2011 1 1 non-cryptographic hash functions • hash table – index on database keys – use: efficient storage and lookup of data • checksum – Example: CRC – Cyclic Redundancy Check • CRC32 uses polynomial division with remainder • initialize: – p = 1 0000 0100 1100 0001 0001 1101 1011 0111 – append 32 zeroes to m • repeat until length (counting from first 1-bit) ≤ 32: – left-align p to leftmost nonzero bit of m – XOR p into m – use: error detection • but only of unintended errors! • non-cryptographic – extremely fast – not secure at all October 20, 2011 2 hash collision • m1, m2 are a collision for h if h(m1) = h(m2) while m1 ≠ m2 I owe you € 100 I owe you € 5000 different documents • there exist a lot of identical hash collisions = – pigeonhole principle collision (a.k.a. Schubladensatz) October 20, 2011 3 2 preimage • given h0, then m is a preimage of h0 if h(m) = h0 X October 20, 2011 4 second preimage • given m0, then m is a second preimage of m0 if h(m) = h(m0 ) while m ≠ m0 ? X October 20, 2011 5 3 cryptographic hash function requirements • collision resistance: it should be computationally infeasible to find a collision m1, m2 for h – i.e. -
Draft Version
Zurich of University the at Security IT on lecture the for reading complementary as ISBN: 978-1-63081-846-3 used be can This text is extracted from the book “Cryptography 101: From Theory to Practice” that was writtentext by Rolf Oppliger and published by Artech House in June 2021 (in its Information Security and Privacy book series). This Zurich of Chapter 1 University the at Introduction Security In this chapter, we pitch the field and introduce the topicIT of the book, namely cryp- tography, at a high operating altitude and level ofon abstraction. More specifically, we elaborate on cryptology (including cryptography) in Section 1.1, address crypto- graphic systems (or cryptosystems for short) in Section 1.2, provide some historical background information in Section 1.3, andlecture outline the rest of the book in Section 1.4. The aim is to lay the basics to understand and put into proper perspective the the contents of the book. for 1.1 CRYPTOLOGY reading The term cryptology is derived from the Greek words “krypt´os,” meaning “hidden,” and “l´ogos,” meaning “word.” Consequently, the term cryptology can be paraphrased as “hidden word.” This refers to the original intent of cryptology, namely to hide the meaning of words and to protect the confidentiality and secrecy of the respective data accordingly. As will (hopefully) become clear throughout the book, this viewpoint is too narrow,complementary and the term cryptology is currently used for many other security- related purposesas and applications in addition to the protection of the confidentiality and secrecy of data. More specifically, cryptology refers to the mathematical science and field of used study that comprises cryptography and cryptanalysis. -
Hash Functions Part II
Cryptographic Hash Functions Part II Cryptography 1 Andreas Hülsing, TU/e Some slides by Sebastiaan de Hoogh, TU/e Hash function design • Create fixed input size building block • Use building block to build compression function • Use „mode“ for length extension Engineering Generic transforms Permutation / Compression Hash function Block cipher function Cryptanalysis / Reductionist proofs best practices 1 (LENGTH-EXTENSION) MODES 2 Merkle-Damgård construction Given: • compression function: CF : {0,1}n x {0,1}r {0,1}n Goal: • Hash function: H : {0,1}* {0,1}n 3 Merkle-Damgård - iterated compression 4 Merkle-Damgård construction • assume that message m can be split up into blocks m1, …, ms of equal block length r – most popular block length is r = 512 • compression function: CF : {0,1}n x {0,1}r {0,1}n • intermediate hash values (length n) as CF input and output • message blocks as second input of CF • start with fixed initial IHV0 (a.k.a. IV = initialization vector) • iterate CF : IHV1 = CF(IHV0,m1), IHV2 = CF(IHV1,m2), …, IHVs = CF(IHVs-1,ms), • take h(m) = IHVs as hash value • advantages: – this design makes streaming possible – hash function analysis becomes compression function analysis – analysis easier because domain of CF is finite 5 padding • padding: add dummy bits to satisfy block length requirement • non-ambiguous padding: add one 1-bit and as many 0-bits as necessary to fill the final block – when original message length is a multiple of the block length, apply padding anyway, adding an extra dummy block – any other non-ambiguous