Additive Complementary Pairs of Codes

An additive code is an Fq-linear subspace of Fqᵐⁿ over Fqᵐ, which is not a linear subspace over Fqᵐ. Linear complementary pairs(LCP) of codes have important roles in cryptography, such as increasing the speed and capacity of digital communication and strengthening security by improving the encryption necessities to resist cryptanalytic attacks. This paper studies an algebraic structure of additive complementary pairs (ACP) of codes over Fqᵐ. Further, we characterize an ACP of codes in analogous generator matrices and parity check matrices. Additionally, we identify a necessary condition for an ACP of codes. Besides, we present some constructions of an ACP of codes over Fqᵐ from LCP codes over Fqᵐ and also from an LCP of codes over Fq. Finally, we study the constacyclic ACP of codes over Fqᵐ and the counting of the constacyclic ACP of codes. As an application of our study, we consider a class of quantum codes called Entanglement Assisted Quantum Error Correcting Code (EAQEC codes). As a consequence, we derive some EAQEC codes.