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Tightly Secure Ring-LWE Based Key Encapsulation with Short Ciphertexts [chapter]

Martin R. Albrecht, Emmanuela Orsini, Kenneth G. Paterson, Guy Peer, Nigel P. Smart
2017 Lecture Notes in Computer Science  
We provide a tight security proof for an IND-CCA Ring-LWE based Key Encapsulation Mechanism that is derived from a generic construction of Dent (IMA Cryptography and Coding, 2003).  ...  The proof technique maybe of interest for other schemes based on LWE and Ring-LWE.  ...  Among the leading candidates for post-quantum public key encryption (PKE) schemes are those based on the Learning with Errors (LWE) problem and its ring equivalent (Ring-LWE).  ... 
doi:10.1007/978-3-319-66402-6_4 fatcat:aod4umhsy5clbft74jyjrub6ei

Two-Message Key Exchange with Strong Security from Ideal Lattices [chapter]

Zheng Yang, Yu Chen, Song Luo
2018 Lecture Notes in Computer Science  
This protocol is mainly based on key encapsulation mechanism (KEM) which is assumed to be secure against chosen plaintext attacks (IND-CPA).  ...  In particular, we propose a new instantiation of OTKEM from Ring Learning with Errors (Ring-LWE) problem in the standard model. This yields a concrete post-quantum TMKE protocol with strong security.  ...  In order to resist with the quantum computer attacks, we introduce a new KEM scheme (for our TMKE construction) based on the presumed hardness of the Ring Learning with Error (Ring-LWE) problem.  ... 
doi:10.1007/978-3-319-76953-0_6 fatcat:pl6ftjnpovaopb7njb3ucrvevy

Will You Cross the Threshold for Me?

Prasanna Ravi, Martianus Frederic Ezerman, Shivam Bhasin, Anupam Chattopadhyay, Sujoy Sinha Roy
2021 Transactions on Cryptographic Hardware and Embedded Systems  
In this work, we propose generic and novel side-channel assisted chosenciphertext attacks on NTRU-based key encapsulation mechanisms (KEMs).  ...  These KEMs are IND-CCA secure, that is, they are secure in the chosen-ciphertext model. Our attacks involve the construction of malformed ciphertexts.  ...  tightly matched security and efficiency [AH21] .  ... 
doi:10.46586/tches.v2022.i1.722-761 fatcat:7gx3tbfndrcozd33rq36k3b4gy

Another Look at Tightness II: Practical Issues in Cryptography [chapter]

Sanjit Chatterjee, Neal Koblitz, Alfred Menezes, Palash Sarkar
2017 Lecture Notes in Computer Science  
How to deal with large tightness gaps in security proofs is a vexing issue in cryptography.  ...  We discuss nontightness in connection with complexity leveraging, HMAC, lattice-based cryptography, identity-based encryption, and hybrid encryption.  ...  Acknowledgments We wish to thank Greg Zaverucha for extensive help with Appendix A as well as useful comments on the other sections, Michael Naehrig for reviewing and commenting on §6, Somindu C.  ... 
doi:10.1007/978-3-319-61273-7_3 fatcat:auyw65hh2rfh3k3hphhrf6mcra

Public-Key Encryption, Revisited: Tight Security and Richer Functionalities

Romain Gay
2019 Zenodo  
In this thesis, we present a new public-key encryption that satisfies a strong security guarantee, that does not degrade with the number of users, and that prevents adversaries from tampering ciphertexts  ...  Our work revisits public-key encryption in two ways: 1) we provide a stronger security guarantee than typical public-key encryption, which handles many users than can collude to perform sophisticated attacks  ...  Multi-ciphertext PCA-secure KEM In this section we describe a tag-based Key Encapsulation Mechanism KEM that is IND-PCAsecure (see Definition 6).  ... 
doi:10.5281/zenodo.3405872 fatcat:ypcfqlzjifephog53uenm4mqm4

Assessment of the Key-Reuse Resilience of NewHope [chapter]

Aurélie Bauer, Henri Gilbert, Guénaël Renault, Mélissa Rossi
2019 Lecture Notes in Computer Science  
NewHope is a suite of two efficient Ring-Learning-With-Error based key encapsulation mechanisms (KEMs) that has been proposed to the NIST call for proposals for post-quantum standardization.  ...  In the case of the CPA-KEM instance of NewHope, they confirm that key reuse (e.g. key caching at server side) should be strictly avoided, even for an extremely short duration.  ...  Motivation With its strong performance and its Ring-LWE based security, NewHope is a high profile candidate of the NIST competition.  ... 
doi:10.1007/978-3-030-12612-4_14 fatcat:er47wsrnozeodbulezbbwd5lp4

Private Stream Aggregation with Labels in the Standard Model

Johannes Ernst, Alexander Koch
2021 Proceedings on Privacy Enhancing Technologies  
We provide an implementation of the scheme with a lattice-based key-homomorphic PRF (secure in the ROM) and measure the performance of the implementation.  ...  The scheme is based on key-homomorphic pseudorandom functions (PRFs) as the only primitive, supports a large message space, scales well for a large number of users and has small ciphertexts.  ...  Alexander Koch was supported by the Competence Center for Applied Security Technology (KASTEL).  ... 
doi:10.2478/popets-2021-0063 fatcat:tndl2nknj5glzfgybscaf64ueq

On Improving Communication Complexity in Cryptography

Lisa Maria Kohl
. - We construct the first scalable encryption scheme with security against active adversaries which has both compact public keys and ciphertexts.  ...  Modern cryptography is concerned with establishing properties such as privacy, integrity and authenticity in protocols for secure communication and computation.  ...  Figure 5 . 5 : 55 Figure 5.5: Ring-LWE based instantiation of PKE with nearly linear decryption, with procedures for HSS from Section 5 6. 3 3 Applying PCGs in Protocols with Correlated Randomness Functionality  ... 
doi:10.5445/ir/1000100363 fatcat:prdzjb46pbforgmk2uq225t7wq

More Efficient Techniques for Adaptively-Secure Cryptography

David Niehues, Bergische Universität Wuppertal
This thesis presents novel identity-based encryption (IBE) schemes and verifiable random functions (VRFs) that achieve adaptive security as outlined above.  ...  may choose the messages based on previously observed interactions.  ...  Moreover, I want to thank my colleagues at the chair of IT-Security and Cryptog-  ... 
doi:10.25926/rdtq-jw45 fatcat:acjimpgvardkzhvpyrv5dx5gdu

Security and Privacy in RFID Systems

Khaled Ouafi
We take a cryptographic viewpoint on the issue and study the extent of security and privacy that RFID-based solutions can offer. v vi       e rest of the dissertation is  ...  is PhD thesis is concerned with authentication protocols using portable lightweight devices such as RFID tags. ese devices have lately gained a signi cant attention for the diversity of the applications  ...  We illustrated a separation between two notions of security for encryption schemes, namely IND-CCA on one side and IND-CPA coupled with PA on the other side.  ... 
doi:10.5075/epfl-thesis-5283 fatcat:sieghhxnfzd2vmpsamhzpz57da