2,878 research outputs found
Threshold Encryption into Multiple Ciphertexts
We propose (T,N) multi-ciphertext scheme for symmetric encryption. The scheme encrypts a message into N distinct ciphertexts. The knowledge of the symmetric key allows decryption of the original message from any ciphertext. Moreover, knowing T+1 ciphertexts allows efficient recovery of the original message without the key (and without revealing the key as well). We define the security property of the scheme, and prove the security of the proposed scheme. We discuss several variants of the basic scheme that provides additional authenticity and efficiency
Enhancement of Secrecy of Block Ciphered Systems by Deliberate Noise
This paper considers the problem of end-end security enhancement by resorting
to deliberate noise injected in ciphertexts. The main goal is to generate a
degraded wiretap channel in application layer over which Wyner-type secrecy
encoding is invoked to deliver additional secure information. More
specifically, we study secrecy enhancement of DES block cipher working in
cipher feedback model (CFB) when adjustable and intentional noise is introduced
into encrypted data in application layer. A verification strategy in exhaustive
search step of linear attack is designed to allow Eve to mount a successful
attack in the noisy environment. Thus, a controllable wiretap channel is
created over multiple frames by taking advantage of errors in Eve's
cryptanalysis, whose secrecy capacity is found for the case of known channel
states at receivers. As a result, additional secure information can be
delivered by performing Wyner type secrecy encoding over super-frames ahead of
encryption, namely, our proposed secrecy encoding-then-encryption scheme. These
secrecy bits could be taken as symmetric keys for upcoming frames. Numerical
results indicate that a sufficiently large secrecy rate can be achieved by
selective noise addition.Comment: 11 pages, 8 figures, journa
Search Me If You Can: Privacy-preserving Location Query Service
Location-Based Service (LBS) becomes increasingly popular with the dramatic
growth of smartphones and social network services (SNS), and its context-rich
functionalities attract considerable users. Many LBS providers use users'
location information to offer them convenience and useful functions. However,
the LBS could greatly breach personal privacy because location itself contains
much information. Hence, preserving location privacy while achieving utility
from it is still an challenging question now. This paper tackles this
non-trivial challenge by designing a suite of novel fine-grained
Privacy-preserving Location Query Protocol (PLQP). Our protocol allows
different levels of location query on encrypted location information for
different users, and it is efficient enough to be applied in mobile platforms.Comment: 9 pages, 1 figure, 2 tables, IEEE INFOCOM 201
Public Key Encryption Supporting Plaintext Equality Test and User-Specified Authorization
In this paper we investigate a category of public key encryption schemes which supports plaintext equality test and user-specified authorization. With this new primitive, two users, who possess their own public/private key pairs, can issue token(s) to a proxy to authorize it to perform plaintext equality test from their ciphertexts. We provide a formal formulation for this primitive, and present a construction with provable security in our security model. To mitigate the risks against the semi-trusted proxies, we enhance the proposed cryptosystem by integrating the concept of computational client puzzles. As a showcase, we construct a secure personal health record application based on this primitive
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