SSIS Packages are Encrypted by Default
By default, SSIS files in development are encypted to prevent an unauthorized person from seeing your SSIS package. The type of encyrption is seamless behind the scene and is at a workstation and user level. So, if you were to send a package that you're developing to another developer on your team, he would not be able to open it by default. This shows you how to fix this problem.

