On the Security of Jhanwar-Barua Identity-Based Encryption Scheme
In , Jhanwar and Barua presented an improvement of the Boneh-Gentry-Hamburg (BGH) scheme. In addition to reducing the time complexity of the algorithm to find a solution of the equation \(ax^2+Sy^2\equiv 1 \bmod n\), their scheme reduces the number of equations to be solved by combining existing solutions. In , Susilo et al. extended the Jhanwar-Barua scheme, reducing more the number of equations to be solved. This paper presents a security flaw that appears in both schemes and shows that they are not IND-ID-CPA secure.
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