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Free software and public administrations

Advantages and positive implications
(1) Developing local industry
(2) Independence from a supplier and market competition
(3) Flexibility and adaptation to specific requirements
(4) Easier adoption of open standards
(5) Public scrutiny of security
(6) Availability in the long term
(7) Impact beyond use on the part of the Administration

 Difficulties of adoption and other problems
(1) Lack of knowledge and political commitment
(2) Poor adaptation of contracting mechanisms
(3) Lack of deployment strategy
(4) Scarcity or lack of free software products in certain segments
(5) Interoperability with existing systems
(6) Data migration

加密演算法

RC4是Ron Rivest在1987年設計的密鑰長度可變的流加密演算法。它加解密使用相同的密鑰，因此也屬於對稱加密演算法。RC4是有線等效加密（WEP）中採用的加密演算法，也是安全套接層（SSL）可採用的演算法之一。

RC4由偽隨機數生成器和異或運算組成。RC4的密鑰長度可變，範圍是[1,255]。RC4一個位元組一個位元組地加解密。給定一個密鑰，偽隨機數生成器接受密鑰併產生一個S盒。S盒用來加密數據，而且在加密過程中S盒會變化。

由於異或運算的對合性，RC4加密解密使用同一套演算法。