the problem is, only source of expalnation what 'simple encryption' is is sybase official dox, and they say almost nothing, just that simple encryption = obfuscation, so it is not encryption, just some internal sybase/sql script or procedure that runs under command 'set hidden'.
Now were this script/procedure is located and under what algorithm it works is the question, no luck with google on this one.
All code / scripts / data I see in db is obfuscated, here is sample of procedure:

hidden '(((((**($)()((($())(((())$()(()(b5!x$!@@5=b!$!5!@S%b5=b(0=0xm%$x($)((()(($)(*)(&*)$(($()()))(*()$!@xbb#=5$W%(@@=!S@b!x@%($!#!5m%((($)(&&*)$(($$%%$)((($()((**)$((@@=0xm!!@bWx5W0$%m%(@@=!.!%@bWx(()()$))(*((((**)$)())()!!$$%%$)5W0$%%S*5!b!m$W@=0xm%$@xbb@0x5bW((((**)$()((((($$!!(((((!!$$%$)(x5W!%%S*5!#%(S*@@$!bmx5!@@=0xm%$*((((**)$)()$$!!%$%$)((()()$))(*@xbb@0x5bWx5W!%.S*@@b!$@@=0xm%$@$)(((()$)))()($(($$!!%$&***$%))(xbbS#$5!!#.S*@@%0@!W%b$bWb!m!b$@)$(((*()()))()*)(($)()((($(()($%x@05=S@S%b5=b(!S@=@xbb#=5$=$!0@#($)(*)(&*)$%$)()*)(($$$$$$!!()((W!5!S*@@@@@@!S@=b!x@S@@=!S@b!x@x)(&&*)$())*)(($****&&&$$$$$$!!((($S*@@@@@@$!b5%@$W!S@=@#$m@=!.!%((**)$)()$$$$!!((()$$()((**)$%$$%@S@@=0xm!!%@$W!(S*@@@@b!$@@=0xm(()$$!!%(($((($$!!$&*&&&$%))(*((%$@xbbS#0xmb!#S*@@!($@%0.S*@@b!m(((!!))(*((((**)$)((!b$@@=0xm%$@xbbS*!($'