China
Africa
Explore chapters and articles related to this topic
Public-Key Encryption
Published in Alfred J. Menezes, Paul C. van Oorschot, Scott A. Vanstone, Handbook of Applied Cryptography, 2018
Alfred J. Menezes, Paul C. van Oorschot, Scott A. Vanstone
8.48 Remark (perfect secrecy vs. semantic security) In Shannon’s theory (see §1.13.3(i)), an encryption scheme has perfect secrecy if a passive adversary, even with infinite computational resources, can learn nothing about the plaintext from the ciphertext, except possibly its length. The limitation of this notion is that perfect secrecy cannot be achieved unless the key is at least as long as the message. By contrast, the notion of semantic security can be viewed as a polynomially bounded version of perfect secrecy — a passive adversary with polynomially bounded computational resources can learn nothing about the plaintext from the ciphertext. It is then conceivable that there exist semantically secure encryption schemes where the keys are much shorter that the messages.
Confidentiality attacks against encrypted control systems
Published in Cyber-Physical Systems, 2023
Amir Mohammad Naseri, Walter Lucia, Amr Youssef
In this paper, we have shown that different attacks can compromise the confidentially of encrypted control systems based on homomorphic cryptosystems. In particular, we have shown that if an attacker is capable of deploying a malware into the plant’s side of the networked control system, then it can leverage intrinsic vulnerabilities (e.g. the limited message space and the randomness required to achieve semantic security of the encryption algorithms) to establish an illegitimate covert communication channel with an eavesdropper on the measurement channel. Then, we have proved that if a trusted re-randomisation unit is used, these disclosure attacks are prevented.
Multi-keywords fuzzy search encryption supporting dynamic update in an intelligent edge network
Published in Connection Science, 2022
Xixi Yan, Pei Yin, Yongli Tang, Suwei Feng
Let , then get . Since , and are negligible, is negligible. For an arbitrary polynomial-time adversary, because and are indistinguishable, the scheme meets the semantic security under the known ciphertext model.
PrivBCS: a privacy-preserving and efficient crowdsourcing system with fine-grained worker selection based on blockchain
Published in Connection Science, 2023
Juan Chen, Wei Liang, Lijun Xiao, Ce Yang, Ronglin Zhang, Zhenwen Gui, Aneta Poniszewska-Marańda
Paillier, based on the difficulty problem of composite residue classes, is a homomorphic encryption algorithm that supports additive homomorphism and number product homomorphism. It consists of three algorithms (Key generation; Encryption; Decryption) as follows: . This algorithm will independently select two random prime numbers p and q of equal length and let them satisfy (this property ensures that the two chosen prime numbers are of equal length). We can calculate N = pq, , and then randomly select another integer (let it satisfy the order of n dividing g) and g satisfies: . Where , is used to calculate the maximum common divisor, is the set of integers less than , is the set of integers mutually prime with . We set the public key , the private key .. This algorithm will choose a random number , for any plaintext message , use the public key to perform encryption, and calculate it as follows: . The ciphertext , since the selection of r is random, Paillier is a probabilistic encryption scheme. Therefore, the same message M can be encrypted with the same public key PK to get different ciphertexts, but it is still the same message after decryption, thus ensuring the semantic security of the ciphertext, which means that a malicious person cannot obtain any information about the plaintext from the ciphertext. That is, a malicious person cannot get any information of the message M from the ciphertext.. This algorithm will decrypt C with , and get plaintext . Specifically, .