Design of Complete E-commerce Security Solutions

SAKEM facilitates the design of complete e-commerce security solutions.

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The design of a complete e-commerce security solution is a significant undertaking. Among other considerations, it comprises the following important issues:

• Electronic identification strategy for routine operations. If security is taken seriously, the designer will look for cryptographic security techniques to ensure transaction authentication. Next, the designer would face a choice between secret key cryptography (SKC) MACing (Message Authentication Code) or public key cryptography (PKC) digital signatures. Once this choice is made, any access control requirement should be met by a challenge-response protocol from either the SKC breed ot the PKC breed.
  
  The SAKEM implied security model suggests the use of SKC MACing for the purpose of transaction authentication.
  
  
• Level of security expected from clients for the secrecy protection of cryptographic keys. The determination of a security level will have impact on the type of electronic identification means given to clients. The choice is between 1) logical security in software-based authentication, or 2) physical security if a security device is introduced into the picture.
  
  For security devices, the SAKEM implied security model widens the range of allowable options (models of security devices supporting the PKC digital signatures are few and usually more expensive).
  
  
• Client authentication strategy upon client enrolment. With the PKC digital signatures, this issue is rooted in the PKI (Public Key Infrastructure) security model, and the role of certification authorities (CA). With SKC, the foremost options are the manual delivery of cryptographic keys or the SAKEM procedure.
  
  Naturally, the SAKEM implied security model suggests the SAKEM procedure for client enrolment. However, the procedure is applicable to other security models as well.
  
  
• Specifications for scope of confidentiality requirements. Even if the critical aspect of e-commerce security is transaction authentication, confidentiality requirements are a significant design issue. This confidentiality requirements issue is independent from the selection of a security model. Obviously, when the confidentiality mechanisms are considered, the selection of SKC or PKC does matter.

Because a typical e-commerce solution has to connect with existing business systems, the transaction authenticity verification has to be integrated with existing applications. This raises a number of software integration issues, notably:

• Presentation level syntax. A presentation level syntax is a formal specifications for formats of records, files, or protocol frames that are object of secure authentication. The challenge is to formalize a data representation which carries a meaningful message into an unambiguous bit string and/or which prevents any cosmetic change to the data that can invalidate a MAC or a digital signature. This issue is independent from the selection of a security model; SKC MACing or PKC digital signature are equally challenging for the required degree of formalism.
  
  
• Integration of authentication algorithms into the application servers. If high transaction volumes are expected, the PKC digital signatures carry a significant processing overhead for which the designer should set a strategy early in the design process. Otherwise, the designer should check the availability of implementations of SKC algorithms and PKC algorithms in the application environment.
  
  The SAKEM implied security model suggests the use of SKC MACing algorithms (actually a MAC operation is made from a block encryption algorithm such as DES or triple-DES), which are more readily available in diverse application computing environments.

So, it is generally easier to address the e-commerce security design issues when the SAKEM implied security model is selected. For customer enrolment, the SAKEM procedure is a comprehensive solution. Throughout the design process for routine operations, the recourse to the SKC suggests techniques which are easier to design with.

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