Research On Communication Encryption Technique Based On DVB-RCS Satellite Communication System

Along with the rapid development of the information globalization and the information Highway,information has become one of the most important strategic resource of the national political and economic development, thus,the information security as well as the communication security which performs as the carrier of information have become an important part of national security. As a result,satellite communication as one of the three major information transmission methods in communication filed?its security communication has inevitably been given high attention and wide studies.The DVB-RCS satellite communication system introduced in this paper is composed of center station, communication satellite and VSAT located country wide and even abroad.Earth station (center station and VSAT) is the interface between satellite system and ground service network,meanwhile the ground service network runs through center station and VSAT forming the basic satellite communication circuit. The bandwidth of this communication circuit has the forward transmission ability of36mbps, while the return channel bandwidth is only2mbps;Transmission between center station and VSAT delay more than600ms while1200ms of delay among VSAT.Based on above,the asymmetric between forward and return channel bandwidth,long transmission delay of DVB-RCS satellite communication system.The research of communication transmission encryption technology done in this paper refers to the data encryption and key management during the satellite transmission, of which,by design an new data encryption system and key management system,the DVB-RCS satellite communication system can provide a more stable,reliable,safer,controllable,efficient data encryption transmission service.In communications confidential system, symmetric block encryption and elliptic curve public key encryption is adopted in data encryption;In order to ensure the key security,security key security system and key distribution protocol are designed in key management.The main difficulties based on all kinds of elliptic curve encryption protocol and realization of efficiency are the point multiplication and the pairing calculation on elliptic curve,due to the fact, this paper pays more attention to the application of elliptic curves in cryptography as the research foundation, and focus on the pairing problem and the fast point multiplication problem in elliptic curve cryptography.The main achievements of this paper are summarized as follow:(1) The key of pairing cryptography is effectively calculating of pairing. This paper introduces the notion of pairing index,and promotes the knowledge of the pairing optimization,meanwhile,constructs a unified mathematical framework for pairing structure and optimization.An efficient algorithm to compute the pairing index group are given by considering the construction of pairing index set and the property of pairing index set.Meanwhile, more pairings are constructed based on the pairing index and corresponding estimation of the complexity is made for the constructed pairings,which make the complexity lower bound of pairing calculation more understanding.(2) Point multiplication on elliptic curves is crucial in elliptic curve cryptosystems.The application of elliptic curves stimulates the numerous techniques for speeding up point multiplication.Gallant et.,proposed a more general algorithm to calculate the homomorphism especially endomorphismsm effectivelly,speed up the calculation of point multiplication on general domain of elliptic curve,which so-called GLV method.Four families elliptic curve are constructed by using CM on elliptic curve. When the GLV method is used to compute point multiplication on these elliptic curves,no extended Euclidean algorithm or lattice basis reduction algorithm is required and it is efficient,whereas only needs to do modular arithmetic simply,so as to accelerate the realization of the GLV method speed.(3) When we speed up elliptic curve point multiplication using the GLV method, generally,we use a lattice reduction algorithm (such as LLL) to gain the reduced lattice for one lattice, and then based which to accelerate the point multiplication.we present the direct construction of a reduced lattice basis of a sublattice of this lattice using the Sylvester matrix associated to two polynomials and give some special properties of the basis.Then we apply our result to the GLV method for point multiplication on Galbraith-Lin-Scott (GLS) curves, which solves some problem proposed by Galbraith et.,(4) The application of elliptic curve cryptography is mainly based on the elliptic curves of Weierstrass form.For elliptic curves in Weierstrass form,the formulas of adding two distinct points and doubling a point are different,which makes elliptic curves cryptosystems vulnerable to side channel analysis.Further,point multiplication on elliptic curves are computed in iteration with the double-and-add algorithm.This is difficult to compute in parallel. As a result a kind of new model for elliptic curve of is proposed. The elliptic curve equation on the model is a symmetrical three polynomial, thereby, comparing with other new model, such as Jacobi four type,Edwards type, this model is very easy to realize matching computation. Mean while, we construct the birational equivalence between this new model and the Weierstrass equation. Formulas of adding two points and doubling a point are given.Further,we present the unified addition formula.Finally,explicit formulas in projective coordinates are given.(5) For designing the confidential system, we design the key management subsystem(KMS),center station confidential subsystem(CCS), VSAT confidential subsystem(VCS),which composed confidentiality system to realize the secret communication. KMS realize the centralized management of all the key (including key production,distribution, update, destroyed,etc) and the control management for CCS and VCS;CCS achieves encryption of business data in forward channel and decryption in return channel;VCS achieves encryption and decryption of business data between two earth stand.In the view of the whole safety about the satellite communication system, this paper does a comprehensive and integrated design for key infrastructure, key usage and key distribution,by using the safe and efficient cryptographic algorithms,the multi-level key protection method,work key using for end to end,to make sure the security of business data,and also designed a protocol to ensure the security of key distribution;Finally,this paper analyzed the safety and feasibility of the system,in order to make sure the feasible and safe of design scheme.