Improving the security of McEliece-like public key cryptosystem based on LDPC codes

Decoding attacks are subjected to McEliece code-based public key cryptosystems. Nowadays, complexity of order 2⁸⁰ is considered to be immune. However, the original McEliece cryptosystem has work factor of order 2⁶⁴ against this kind of attacks. There aren´t any immune methods to avoid this kind of attacks except increasing code parameters, whereas, this modifications make McEliece cryptosystem impractical. In this paper we improve the security level of LDPC based McEliece cryptosystem i.e. Baldi´s cryptosystem about 2²³ operations to achieve the work factor of 2⁹⁴, without any remarkable increment in key-size or any decrement in transmission rate or speed of cryptosystem.