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.

Efficient Adaptively Secure IBBE From the SXDH Assumption

Abstract: This paper describes the first constructions of identity-based broadcast encryption (IBBE) using Type-3 pairings, which can be proved secure against adaptive-identity attacks based on the Symmetric eXternal Diffie–Hellman assumption (which is a static, if not a standard, assumption) achieving a security degradation which is not exponential in the size of the target identity set. The constructions are obtained by extending the currently known most efficient identity-based encryption scheme proposed by Jutla and Roy in 2013. The new constructions fill both a practical and a theoretical gap in the literature on efficient IBBE schemes.

Generalized Key Delegation for Wildcarded Identity-Based and Inner-Product Encryption

Abstract: Inspired by the fact that many e-mail addresses correspond to groups of users, Abdalla introduced the notion of identity-based encryption with wildcards (WIBE), which allows a sender to simultaneously encrypt messages to a group of users matching a certain pattern, defined as a sequence of identity strings and wildcards. This notion was later generalized by Abdalla, Kiltz, and Neven, who considered more general delegation patterns during the key derivation process. Despite its many applications, current constructions have two significant limitations: 1) they are only known to be fully secure when the maximum hierarchy depth is a constant; and 2) they do not hide the pattern associated with the ciphertext. To overcome these, this paper offers two new constructions. First, we show how to convert a WIBE scheme of Abdalla into a (nonanonymous) WIBE scheme with generalized key delegation (WW-IBE) that is fully secure even for polynomially many levels. Then, to achieve anonymity, we initially consider hierarchical predicate encryption (HPE) schemes with more generalized forms of key delegation and use them to construct an anonymous WW-IBE scheme. Finally, to instantiate the former, we modify the HPE scheme of Lewko to allow for more general key delegation patterns. Our proofs are in the standard model and use existing complexity assumptions.

Sender-Side Public Key Deniable Encryption Scheme

Abstract: Consider a situation in which the transmission of encrypted message is intercepted by an adversary who can later ask the sender to reveal the random choices (and also the secret key, if one exists) used in generating the cipher text, thereby exposing the plaintext. An encryption scheme is deniable if the sender can generate `fake random choice' that will make the cipher text `look like' an encryption of a different plaintext, thus keeping the real plaintext private. Analogous requirements can be formulated with respect to attacking the receiver and with respect to attacking both parties. In this paper we propose a scheme for the sender side deniable encryption.

Cryptoanalysis of the Immunized LL Public Key Systems

Abstract: In CRYPTO '93 Lim and Lee provided a valuable investigation of public key encryption systems secure against adaptive chosen ciphertext attacks. In this paper we identify several insecurities of both their RSA and El Gamal based schemes. We first demonstrate that the RSA based scheme is insecure under an adaptive chosen ciphertext attack. We also point weaknesses in the design of both their RSA and EI Gamal based schemes regarding the use of pseudorandom-generators, and in particular show that their choice of pseudorandom-generators for the RSA based scheme may be insecure even with respect to a known ciphertext only attack.They further claim that their schemes are particularly useful in the context of group-oriented cryptosystems due to the unique verification method used. (In fact their scheme is the only group-oriented practical encryption claimed to be secure against chosen ciphertext attacks). Group oriented cryptosystems distribute the decryption process amongst a multiple of individuals in order to provide a mechanism in which no single person is trusted. We further demonstrate that both their schemes are completely insecure in this setting.

Image encryption using a new chaos based encryption algorithm

Abstract: Encryption is a process of converting an image from readable to unreadable form. Various Image encryption algorithm based on permutation and diffusion have been proposed However, most of the algorithm for the permutation process uses the chaos sequence to permute the image and considerably takes more time in shuffling the position of the image pixel. In this paper we proposed a new effective algorithm based on permutation-diffusion for image encryption to reduce the processing time of the encryption considerably. To make the encryption more stronger and confused, same image is fed to the diffusion process after permutation process. In the present work diffusion process is carried out with the traditional AES algorithm. Theoretical analyses and computer simulations both confirm that the new algorithm has high security and is very fast for practical image encryption.