Why textbook elgamal

The attack shows that without proper preprocessing of the plaintexts, both ElGamal and RSA encryption are fundamentally insecure. Namely, when one uses these systems to encrypt a short secret key of a symmetric cipher it is often possible to recover the secret key from the ciphertext.

Our results demonstrate that preprocessing messages prior to encryption is an essential part of both systems. View via Publisher. Save to Library Save. Create Alert Alert. Share This Paper. Background Citations. Methods Citations. Results Citations. Tables and Topics from this paper. Citation Type. Has PDF. Publication Type. More Filters. View 1 excerpt, cites background. Decrypting the ciphertexts of RSA cryptosystem with ciphering function.

The RSA is based on a trapdoor one-way function which is easy to compute but is most hard to revert without knowing the trapdoor. A cryptanalysis, presented in this paper, consists in finding a new … Expand. View 1 excerpt, cites methods. On the security of some variants of rsa. The RSA cryptosystem, named after its inventors, Rivest, Shamir and Adleman, is the most widely known and widely used public-key cryptosystem in the world today.

I couldn't find any suitable source to explain why we should use q as order of our group and avoid p What have I tried? So I think there is something wrong with its security! This is the only security issue in the question's example. No , if «use» refers to the plaintext set. How is left as an exercise to the reader. This property breaks security under Chosen Plaintext Attack, and even weaker notions. As stated, the textbook solution to the problem in 2 is to restrict the plaintext to the subgroup of quadratic residues.

But when we encipher arbitrary data, like a name on the class roll, that won't do. In practice that's solved using hybrid encryption. It is an easy paper to read and worthwhile going through the details there. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. ElGamal encryption security Ask Question. Asked 8 months ago.

Active 8 months ago. Viewed times. Most websites and sources just say: use cyclic group of order q without any explanation. Improve this question. Add a comment.