342 research outputs found
Semantic Security and Indistinguishability in the Quantum World
At CRYPTO 2013, Boneh and Zhandry initiated the study of quantum-secure
encryption. They proposed first indistinguishability definitions for the
quantum world where the actual indistinguishability only holds for classical
messages, and they provide arguments why it might be hard to achieve a stronger
notion. In this work, we show that stronger notions are achievable, where the
indistinguishability holds for quantum superpositions of messages. We
investigate exhaustively the possibilities and subtle differences in defining
such a quantum indistinguishability notion for symmetric-key encryption
schemes. We justify our stronger definition by showing its equivalence to novel
quantum semantic-security notions that we introduce. Furthermore, we show that
our new security definitions cannot be achieved by a large class of ciphers --
those which are quasi-preserving the message length. On the other hand, we
provide a secure construction based on quantum-resistant pseudorandom
permutations; this construction can be used as a generic transformation for
turning a large class of encryption schemes into quantum indistinguishable and
hence quantum semantically secure ones. Moreover, our construction is the first
completely classical encryption scheme shown to be secure against an even
stronger notion of indistinguishability, which was previously known to be
achievable only by using quantum messages and arbitrary quantum encryption
circuits.Comment: 37 pages, 2 figure
Using Simon's Algorithm to Attack Symmetric-Key Cryptographic Primitives
We present new connections between quantum information and the field of
classical cryptography. In particular, we provide examples where Simon's
algorithm can be used to show insecurity of commonly used cryptographic
symmetric-key primitives. Specifically, these examples consist of a quantum
distinguisher for the 3-round Feistel network and a forgery attack on CBC-MAC
which forges a tag for a chosen-prefix message querying only other messages (of
the same length). We assume that an adversary has quantum-oracle access to the
respective classical primitives. Similar results have been achieved recently in
independent work by Kaplan et al. Our findings shed new light on the
post-quantum security of cryptographic schemes and underline that classical
security proofs of cryptographic constructions need to be revisited in light of
quantum attackers.Comment: 14 pages, 2 figures. v3: final polished version, more formal
definitions adde
07021 Abstracts Collection -- Symmetric Cryptography
From .. to .., the Dagstuhl Seminar 07021 ``Symmetric Cryptography\u27\u27 automatically
was held in the International Conference and Research Center (IBFI),
Schloss Dagstuhl.
During the seminar, several participants presented their current
research, and ongoing work and open problems were discussed. Abstracts of
the presentations given during the seminar as well as abstracts of
seminar results and ideas are put together in this paper. The first section
describes the seminar topics and goals in general.
Links to extended abstracts or full papers are provided, if available
LPsec: a fast and secure cryptographic system for optical connections
High capacity and low latency of optical connections are ideal for supporting current and future communication services, including 5G and beyond. Although some of those services are already secured at the packet layer using standard stream ciphers, like the Advanced Encryption Standard and ChaCha, secure transmission at the optical layer is still not implemented. To secure the optical layer, cryptographic methods need to be fast enough to support high-speed optical transmission and cannot introduce significant delay. Moreover, methods for key exchange, key generation, and key expansion are required, which can be implemented on standard coherent transponders. In this paper, we propose Light Path SECurity (LPsec), a secure cryptographic solution for optical connections that involves fast data encryption using stream ciphers and key exchange using Diffie–Hellman protocol through the optical channel. To support encryption of high-speed data streams, a fast, general-purpose pseudorandom number generator is used. Moreover, to make the scheme more secure against exhaustive search attacks, an additional substitution cipher is proposed. In contrast to the limited encryption speeds that standard stream ciphers can support, LPsec can support high-speed rates. Numerical simulation for 16 quadrature amplitude modulation (QAM), 32-QAM, and 64-QAM show that LPsec provides a sufficient security level while introducing only negligible delay.H2020 Industrial Leadership [H2020 B5G-OPEN (101016663)]; H2020 Marie Skłodowska-Curie Actions [REALNET (813144)]; Agencia Estatal de Investigación [IBON (PID2020- 114135RB-I00)]; Institució Catalana de Recerca i Estudis Avançats.Peer ReviewedPostprint (author's final draft
ABC - A New Framework for Block Ciphers
We suggest a new framework for block ciphers named Advanced Block Cipher, or shortly ABC. ABC has additional non-secret parameters that ensure that each call to the underlying block cipher uses a different pseudo-random permutation. It therefore ensures that attacks that require more than one block encrypted under the same secret permutation cannot apply. In particular, this framework protects against dictionary attacks, and differential and linear attacks, and eliminates weaknesses of ECB and CBC modes. This new framework shares a common structure with HAIFA, and can share the same logic with HAIFA compression functions. We analyze the security of several modes of operation for ABCs block ciphers, and suggest a few instances of ABCs
Cryptology and Data Communications
Research reported herein was conducted at the Artificial Intelligence Laboratory, a Massachusetts Institute of Technology research program supported in part by the Advanced Research Projects Agency of the Department of Defense and monitored by the office of Naval Research under contract N00014-75-C-0643.This paper is divided into two parts. The first part deals with cryptosystems and cryptanalysis. It surveys the basic information about cryptosystems and then addresses two specific questions. Are cryptosystems such as LUCIFER which are based on the ideas of Feistel and Shannon secure for all practical purposes? Is the proposed NBS standard cryptosystem secure for all practical purposes? This paper argues that the answer to the first question is "they might well be" and that the answer to the second is "no."
The second part of this paper considers how a cryptosystem can be used to provide security of data transmission in a computer environment. It discusses the two basic aspects of security: secrecy and authentication. It then describes and discusses a specific proposal by Kent of a set of protocols designed to provide security through encryption. Finally, an alternate proposal is given in order to explore some of the other design choices which could have been made.MIT Artificial Intelligence Laboratory
Department of Defense Advanced Research Projects Agenc
A new hardware-assisted PIR with O(n) shuffle cost
Ministry of Education, Singapore under its Academic Research Funding Tier
Secure ADS-B: Towards Airborne Communications Security in the Federal Aviation Administration\u27s Next Generation Air Transportation System
The U.S. Congress has mandated that all aircraft operating within the National Airspace System, military or civilian, be equipped with ADS-B transponders by the year 2020. The ADS-B aircraft tracking system, part of the Federal Aviation Administration\u27s NextGen overhaul of the Air Transportation System, replaces Radar-based surveillance with a more accurate satellite-based surveillance system. However, the unencrypted nature of ADS-B communication poses an operational security risk to military and law enforcement aircraft conducting sensitive missions. The non-standard format of its message and the legacy communication channels used by its transponders make the ADS-B system unsuitable for traditional encryption mechanisms. FPE, a recent development in cryptography, provides the ability to encrypt arbitrarily formatted data without padding or truncation. Indeed, three new algorithms recommended by the NIST, may be suitable for encryption of ADS-B messages. This research assesses the security and hardware performance characteristics of the FF1, FF2, and FF3 algorithms, in terms of entropy of ciphertext, operational latency and resource utilization when implemented on a Field-Programmable Gate Array. While all of the algorithms inherit the security characteristics of the underlying AES block cipher, they exhibit differences in their performance profiles. Findings demonstrate that a Bump-in-the-Wire FPE cryptographic engine is a suitable solution for retrofitting encryption to ADS-B communication
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