scholarly journals A Fully Secure KP-ABE Scheme on Prime-Order Bilinear Groups through Selective Techniques

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Isaac Amankona Obiri ◽  
Qi Xia ◽  
Hu Xia ◽  
Kwame Opuni-Boachie Obour Agyekum ◽  
Kwame Omono Asamoah ◽  
...  
Keyword(s):  
Prime Order ◽  
Security Models ◽  
Security Proof ◽  
Cryptographic Primitive ◽  
Encryption Schemes ◽  
Monotone Span Programs ◽  
Span Programs ◽  
Proof Techniques ◽  
End To End ◽  
Selective Security

Key-policy attribute-based encryption (KP-ABE) is the cryptographic primitive which enables fine grained access control while still providing end-to-end encryption. Although traditional encryption schemes can provide end-to-end encryption, users have to either share the same decryption keys or the data have to be stored in multiple instances which are encrypted with different keys. Both of these options are undesirable. However, KP-ABE can provide less key overhead compared to the traditional encryption schemes. While there are a lot of KP-ABE schemes, none of them simultaneously supports multiuse of attributes, adaptive security, monotone span programs, and static security assumption. Hence, we propose a fully secure KP-ABE scheme for monotone span programs in prime-order group. This scheme uses selective security proof techniques to obtain the requisite ingredients for full security proof. This strengthens the correlation between selective and full security models and enables the transition of the best qualities in selective security models to fully secure systems. The security proof is based on decisional linear assumption and three-party Diffie–Hellman assumption.

scholarly journals Compositional optimizations for CertiCoq

2021 ◽  
Vol 5 (ICFP) ◽  
pp. 1-30
Author(s):  
Zoe Paraskevopoulou ◽  
John M. Li ◽  
Andrew W. Appel
Keyword(s):  
Difficult Problem ◽  
Higher Order ◽  
Additional Restriction ◽  
Logical Relation ◽  
Compositional Verification ◽  
Compiler Correctness ◽  
Separate Compilation ◽  
Proof Techniques ◽  
End To End ◽  
Program Components

Compositional compiler verification is a difficult problem that focuses on separate compilation of program components with possibly different verified compilers. Logical relations are widely used in proving correctness of program transformations in higher-order languages; however, they do not scale to compositional verification of multi-pass compilers due to their lack of transitivity. The only known technique to apply to compositional verification of multi-pass compilers for higher-order languages is parametric inter-language simulations (PILS), which is however significantly more complicated than traditional proof techniques for compiler correctness. In this paper, we present a novel verification framework for lightweight compositional compiler correctness . We demonstrate that by imposing the additional restriction that program components are compiled by pipelines that go through the same sequence of intermediate representations , logical relation proofs can be transitively composed in order to derive an end-to-end compositional specification for multi-pass compiler pipelines. Unlike traditional logical-relation frameworks, our framework supports divergence preservation—even when transformations reduce the number of program steps. We achieve this by parameterizing our logical relations with a pair of relational invariants . We apply this technique to verify a multi-pass, optimizing middle-end pipeline for CertiCoq, a compiler from Gallina (Coq’s specification language) to C. The pipeline optimizes and closure-converts an untyped functional intermediate language (ANF or CPS) to a subset of that language without nested functions, which can be easily code-generated to low-level languages. Notably, our pipeline performs more complex closure-allocation optimizations than the state of the art in verified compilation. Using our novel verification framework, we prove an end-to-end theorem for our pipeline that covers both termination and divergence and applies to whole-program and separate compilation, even when different modules are compiled with different optimizations. Our results are mechanized in the Coq proof assistant.

scholarly journals Lower Bounds for Monotone Span Programs

1994 ◽  
Vol 1 (46) ◽  
Author(s):  
Amos Beimel
Keyword(s):  
Lower Bounds ◽  
Secret Sharing ◽  
Algebraic Model ◽  
New Technique ◽  
Secret Sharing Schemes ◽  
Branching Programs ◽  
Model Of Computation ◽  
Monotone Span Programs ◽  
Span Programs ◽  
A New Technique

The model of span programs is a linear algebraic model of computation. Lower bounds for span programs imply lower bounds for contact schemes, symmetric branching programs and for formula size. Monotone span programs correspond also to linear secret-sharing schemes. We present a new technique for proving lower bounds for monotone span programs. The main result proved here yields quadratic lower bounds for the size of monotone span programs, improving on the largest previously known bounds for explicit functions. The bound is asymptotically tight for the function corresponding to a class of 4-cliques.

scholarly journals The State of the Authenticated Encryption

2016 ◽  
Vol 67 (1) ◽  
pp. 167-190
Author(s):  
Damian Vizár
Keyword(s):  
The State ◽  
Authenticated Encryption ◽  
Research Activity ◽  
Cryptographic Primitive ◽  
Encryption Schemes ◽  
Caesar Competition ◽  
Symmetric Key

Abstract Ensuring confidentiality and integrity of communication remains among the most important goals of cryptography. The notion of authenticated encryption marries these two security goals in a single symmetric-key, cryptographic primitive. A lot of effort has been invested in authenticated encryption during the fifteen years of its existence. The recent Competition for Authenticated Encryption: Security, Applicability, and Robustness (CAESAR) has boosted the research activity in this area even more. As a result, the area of authenticated encryption boasts numerous results, both theoretically and practically oriented, and perhaps even greater number of constructions of authenticated encryption schemes. We explore the current landscape of results on authenticated encryption. We review the CEASAR competition and its candidates, the most popular construction principles, and various design goals for authenticated encryption, many of which appeared during the CAESAR competition. We also take a closer look at the candidate Offset Merkle-Damgård (OMD).

scholarly journals Sender-equivocable encryption schemes secure against chosen-ciphertext attacks revisited

2015 ◽  
Vol 25 (2) ◽  
pp. 415-430
Author(s):  
Zhengan Huang ◽  
Shengli Liu ◽  
Baodong Qin ◽  
Kefei Chen
Keyword(s):  
Security Analysis ◽  
Encryption Scheme ◽  
Authentication Code ◽  
Security Proof ◽  
Encryption Schemes ◽  
Challenge Ciphertext ◽  
The Cross ◽  
Security Game

Abstract Fehr et al. (2010) proposed the first sender-equivocable encryption scheme secure against chosen-ciphertext attacks (NCCCA) and proved that NC-CCA security implies security against selective opening chosen-ciphertext attacks (SO-CCA). The NC-CCA security proof of the scheme relies on security against substitution attacks of a new primitive, the “crossauthentication code”. However, the security of the cross-authentication code cannot be guaranteed when all the keys used in the code are exposed. Our key observation is that, in the NC-CCA security game, the randomness used in the generation of the challenge ciphertext is exposed to the adversary. Based on this observation, we provide a security analysis of Fehr et al.’s scheme, showing that its NC-CCA security proof is flawed. We also point out that the scheme of Fehr et al. encrypting a single-bit plaintext can be refined to achieve NC-CCA security, free of the cross-authentication code. Furthermore, we propose the notion of “strong cross-authentication code”, apply it to Fehr et al.’s scheme, and show that the new version of the latter achieves NC-CCA security for multi-bit plaintexts.

scholarly journals Finite-size security of continuous-variable quantum key distribution with digital signal processing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Takaya Matsuura ◽  
Kento Maeda ◽  
Toshihiko Sasaki ◽  
Masato Koashi
Keyword(s):  
Signal Processing ◽  
Wavelength Division Multiplexing ◽  
Quantum Key Distribution ◽  
Finite Size ◽  
Digital Signal ◽  
Key Distribution ◽  
Continuous Variable ◽  
Wavelength Division ◽  
Security Proof ◽  
Proof Techniques

AbstractIn comparison to conventional discrete-variable (DV) quantum key distribution (QKD), continuous-variable (CV) QKD with homodyne/heterodyne measurements has distinct advantages of lower-cost implementation and affinity to wavelength division multiplexing. On the other hand, its continuous nature makes it harder to accommodate to practical signal processing, which is always discretized, leading to lack of complete security proofs so far. Here we propose a tight and robust method of estimating fidelity of an optical pulse to a coherent state via heterodyne measurements. We then construct a binary phase modulated CV-QKD protocol and prove its security in the finite-key-size regime against general coherent attacks, based on proof techniques of DV QKD. Such a complete security proof is indispensable for exploiting the benefits of CV QKD.

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