formula written and cloaked

I need a spreadsheet formula written (in column B) to change a column of 4 digit numbers (in column A) as such: 1. reverse the number sequence (i.e. 1243 would become 3421), then 2. add or subract 1012 to the number from 1 above (the higher of the two would be chosen unless it was more than 4 digits, and also the first number cannot be 0!) 3. swap the second and third number (i.e. 4433 would become 4343) Also, the formula spreadsheet will be used by someone who will NOT know the formula. I am the only one who will know it, so it needs to be "cloaked" somehow... Thx!