HELEN: A Public-Key Cryptosystem Based on the LPN and the Decisional Minimal Distance Problems

We propose HELEN, a code-based public-key cryptosystem whose security is based on the hardness of the Learning from Parity with Noise problem (LPN) and the decisional minimum distance problem. We show that the resulting cryptosystem achieves indistinguishability under chosen plaintext attacks (IND-CPA security). Using the Fujisaki-Okamoto generic construction, HELEN achieves IND-CCA security in the random oracle model. Our cryptosystem looks like the Alekhnovich cryptosystem. However, we carefully study its complexity and we further propose concrete optimized parameters.