Questions tagged [universal-re-encryption]

This is the paper. On page 6, the paper describes a variant of El Gamal and a way of re-encrypting ciphertexts. I thought an easier way to do encryption is to output $(m(g^x)^y,g^y)$, and universal re-encryption can be done by…

I've been thinking about a geometric picture for El-Gamal. The idea is to understand the set $\{(my^{x},g^x) \mid x \in Z_p\}$ (the set of encryption of $m$ for fixed $g$ and $y$) by taking the $\log_g$ and getting $\{(\log m + x\log y, x) \mid x…

Universal reencryption is an interesting encryption primitive. Attempts to build signatures schemes or protocols with authentication incorporating it have frequently failed though. A plausible application of a signature scheme employing universal…

GM is a cryptosystem with a modulus $N = pq$ ($p$, $q$ prime) and quadratic nonresidue $r \in (\Bbb Z / N\Bbb Z)^*$ as the public key. You can see the details on Wikipedia. Anyway, let's say that $N < 2^{1024}$. Then the ciphertext can be…