Plaintext-aware encryption

About: Plaintext-aware encryption is a research topic. Over the lifetime, 1980 publications have been published within this topic receiving 101775 citations. The topic is also known as: Plaintext awareness.

Secure hybrid encryption from weakened key encapsulation

Abstract: We put forward a new paradigm for building hybrid encryption schemes from constrained chosen-ciphertext secure (CCCA) key-encapsulation mechanisms (KEMs) plus authenticated symmetric encryption. Constrained chosen-ciphertext security is a new security notion for KEMs that we propose. It has less demanding security requirements than standard CCCA security (since it requires the adversary to have a certain plaintext-knowledge when making a decapsulation query) yet we can prove that it is CCCA sufficient for secure hybrid encryption. Our notion is not only useful to express the Kurosawa-Desmedt public-key encryption scheme and its generalizations to hash-proof systems in an abstract KEM/DEM security framework. It also has a very constructive appeal, which we demonstrate with a new encryption scheme whose security relies on a class of intractability assumptions that we show (in the generic group model) strictly weaker than the Decision Diffie-Hellman (DDH) assumption. This appears to be the first practical public-key encryption scheme in the literature from an algebraic assumption strictly weaker than DDH.

Cryptanalysis of a chaotic image encryption method

Abstract: The security of digital images attracts much attention recently, and many image encryption methods have been proposed. In IS-CAS2000, a new chaotic key-based algorithm (CKBA) for image encryption was proposed. This paper points out CKBA is very weak to the chosen/known-plaintext attack with only one plain-image, and its security to brute-force ciphertext-only attack is overestimated by the authors. That is to say, CKBA is not secure at all from cryptographic viewpoint. Some experiments are made to show the feasibility of the chosen/known-plaintext attack. We also discuss some remedies to the original scheme and their performance, and we find none of them can essentially improve the security of CKBA.

REACT: Rapid Enhanced-Security Asymmetric Cryptosystem Transform

Abstract: Seven years after the optimal asymmetric encryption padding (OAEP) which makes chosen-ciphertext secure encryption scheme from any trapdoor one-way permutation (but whose unique application is RSA), this paper presents REACT, a new conversion which applies to any weakly secure cryptosystem, in the random oracle model: it is optimal from both the computational and the security points of view. Indeed, the overload is negligible, since it just consists of two more hashings for both encryption and decryption, and the reduction is very tight. Furthermore, advantages of REACT beyond OAEP are numerous: 1. it is more general since it applies to any partially trapdoor one-way function (a.k.a. weakly secure public-key encryption scheme) and therefore provides security relative to RSA but also to the Diffie-Hellman problem or the factorization; 2. it is possible to integrate symmetric encryption (block and stream ciphers) to reach very high speed rates; 3. it provides a key distribution with session key encryption, whose overall scheme achieves chosen-ciphertext security even with weakly secure symmetric scheme.Therefore, REACT could become a new alternative to OAEP, and even reach security relative to factorization, while allowing symmetric integration.

A secret key cryptosystem by iterating a chaotic map

Abstract: Chaos is introduced to cryptology. As an example of the applications, a secret key cryptosystem by iterating a one dimensional chaotic map is proposed. This system is based on the characteristics of chaos, which are sensitivity of parameters, sensitivity of initial points, and randomness of sequences obtained by iterating a chaotic map. A ciphertext is obtained by the iteration of a inverse chaotic map from an initial point, which denotes a plaintext. If the times of the iteration is large enough, the randomness of the encryption and the decryption function is so large that attackers cannot break this cryptosystem by statistic characteristics. In addition to the security of the statistical point, even if the cryptosystem is composed by a tent map, which is one of the simplest chaotic maps, setting a finite computation size avoids a ciphertext only attack. The most attractive point of the cryptosystem is that the cryptosystem is composed by only iterating a simple calculations though the information rate of the cryptosystem is about 0.5.