A necessary condition for CPA-security of randomized symmetric code cryptosystems

We investigate a class of symmetric code cryptosystems constructed similarly to the well-known randomized (asymmetric) McEliece cryptosystem. A necessary condition for CPA- security of such cryptosystems is obtained (that is, their security against arbitrary distinguishing chosen-plaintext attacks). To each randomized code cryptosystem of specified type correspond its shortening, which is its reduced version. It is proved that the CPA-security of the input cryptosystem imply the CPA-security of its shortening. To a certain extent, this makes it possible to reduce the question about the CPA-security of randomized code cryptosystems to similar question about cryptosystems that have simpler structure. The obtained result can be used in further research in the construction of provable secure symmetric code cryptosystems.

MSB BASED IMAGE STEGANOGRAPHY USING MCELIECE CRYPTOSYSTEM

Steganography is the science of embedding secret data inside data so they can be sent to destination security. Encryption algorithms used to save information from sly activities when sent from one device to another over the wireless network. In this paper McEliece will be used to text encryption by Goppa code, where McEliece cryptosystem is a public-key cryptosystem based on error-correcting codes; then embedding the ciphertext as steganography image by MSB method. This lead to save information from attackers.

A New Class of Q-Ary Codes for the McEliece Cryptosystem

The McEliece cryptosystem is a promising candidate for post-quantum public-key encryption. In this work, we propose q-ary codes over Gaussian integers for the McEliece system and a new channel model. With this one Mannheim error channel, errors are limited to weight one. We investigate the channel capacity of this channel and discuss its relation to the McEliece system. The proposed codes are based on a simple product code construction and have a low complexity decoding algorithm. For the one Mannheim error channel, these codes achieve a higher error correction capability than maximum distance separable codes with bounded minimum distance decoding. This improves the work factor regarding decoding attacks based on information-set decoding.