symmetric key
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2022 ◽  
Author(s):  
Vijay Kumar Yadav ◽  
Nitish Andola ◽  
Shekhar Verma ◽  
S Venkatesan

Oblivious transfer (OT) protocol is an essential tool in cryptography that provides a wide range of applications like secure multi-party computation, private information retrieval, private set intersection, contract signing, and privacy-preserving location-based services. The OT protocol has different variants such as one-out-of-2, one-out-of- n , k -out-of- n , and OT extension. In the OT (one-out-of-2, one-out-of- n , and OT extension) protocol, the sender has a set of messages, whereas the receiver has a key. The receiver sends that key to the sender in a secure way; the sender cannot get any information about the received key. The sender encrypts every message by operating on every message using the received key and sends all the encrypted messages to the receiver. The receiver is able to extract only the required message using his key. However, in the k -out-of- n OT protocol, the receiver sends a set of k keys to the sender, and in replay, the sender sends all the encrypted messages. The receiver uses his keys and extracts the required messages, but it cannot gain any information about the messages that it has not requested. Generally, the OT protocol requires high communication and computation cost if we transfer millions of oblivious messages. The OT extension protocol provides a solution for this, where the receiver transfers a set of keys to the sender by executing a few numbers of OT protocols. Then, the sender encrypts all the messages using cheap symmetric key cryptography with the help of a received set of keys and transfer millions of oblivious messages to the receiver. In this work, we present different variants of OT protocols such as one-out-of-2, one-out-of- n , k -out-of- n , and OT extension. Furthermore, we cover various aspects of theoretical security guarantees such as semi-honest and malicious adversaries, universally composable, used techniques, computation, and communication efficiency aspects. From the analysis, we found that the semi-honest adversary-based OT protocols required low communication and computation costs as compared to malicious adversary-based OT protocols.


IEEE Access ◽  
2022 ◽  
pp. 1-1
Author(s):  
Kristtopher Kayo Coelho ◽  
Michele Nogueira ◽  
Mateus Coutinho Marim ◽  
Edelberto Franco Silva ◽  
Alex Borges Vieira ◽  
...  

Author(s):  
Kinjal Raut

Abstract: The internet has revolutionized advancements, it’s conveniences and uses come at the price of new perils. To be safe from being the victim of fraud, theft and other damage security and vigilance is critical. Cryptography plays an important role in securing information and communications using a set of rules, it ensures the integrity of our data. It maintains confidentiality by protecting the privacy of personal information stored in enterprise systems. Hence Encryption is the only way to ensure that your information remains secure while it is stored and being transmitted. Cryptographic Algorithms mathematically maintain the integrity, confidentiality and authenticity of sensitive information by preventing data disclosure, data tampering and repudiation. The three main types of cryptography are Symmetric Key Cryptography, Asymmetric Key Cryptography and Hash Functions. In this Paper, several important algorithms used for encryption and decryption are defined and analysed, the algorithms are DES, AES, ECC, RSA, MD5 Keywords: Cryptography, Encryption, Decryption, AES, DES, ECC, RSA, Blowfish, MD5


2021 ◽  
Author(s):  
Jean Belo KLAMTI ◽  
Anwar Hasan

A key encapsulation mechanism (KEM) that takes as input an arbitrary string, i.e., a tag, is known as tag-KEM, while a scheme that combines signature and encryption is called signcryption. In this paper, we present a code-based signcryption tag-KEM scheme. We utilize a code-based signature and a CCA2 (adaptive chosen ciphertext attack) secure version of McEliece's {encryption} scheme. The proposed scheme uses an equivalent subcode as a public code for the receiver, making the NP-completeness of the equivalent subcode problem be one of our main security assumptions. We then base the signcryption tag-KEM to design a code-based hybrid signcryption scheme. A hybrid scheme deploys an asymmetric- as well as a symmetric-key encryption. We give security analyses of both our schemes in the standard model and prove that they are secure against IND-CCA2 (indistinguishability under adaptive chosen ciphertext attack) and SUF-CMA (strong existential unforgeability under chosen message attack).


2021 ◽  
Author(s):  
Jean Belo KLAMTI ◽  
Anwar Hasan

A key encapsulation mechanism (KEM) that takes as input an arbitrary string, i.e., a tag, is known as tag-KEM, while a scheme that combines signature and encryption is called signcryption. In this paper, we present a code-based signcryption tag-KEM scheme. We utilize a code-based signature and a CCA2 (adaptive chosen ciphertext attack) secure version of McEliece's {encryption} scheme. The proposed scheme uses an equivalent subcode as a public code for the receiver, making the NP-completeness of the equivalent subcode problem be one of our main security assumptions. We then base the signcryption tag-KEM to design a code-based hybrid signcryption scheme. A hybrid scheme deploys an asymmetric- as well as a symmetric-key encryption. We give security analyses of both our schemes in the standard model and prove that they are secure against IND-CCA2 (indistinguishability under adaptive chosen ciphertext attack) and SUF-CMA (strong existential unforgeability under chosen message attack).


2021 ◽  
Vol 26 (6) ◽  
pp. 585-590
Author(s):  
Ratnakumari Challa ◽  
VijayaKumari Gunta

Homomorphic encryption (HE) schemes became popular cryptographic primitives and very useful in variety of security applications. Homomorphic encryption based on coding theory have the advantages of faster computations due to the structural properties of the codes used. Several schemes are supporting unlimited Mod2 addition operations in literature. The present paper introduces Reed-Muller (RM) code based Mod2 multiplication operation thereby making RM code based HE scheme fully homomorphic. The representation of the codeword with necessary adaption to support unlimited number of Mod2​ multiplication operations is presented along with the scheme first. The correctness proof of the homomorphic operations along with experimental evaluation is also presented to demonstrate the practical aspects of the proposal.


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