As per specifications document, 

"*We have the natural restriction that at least two characters must be ciphered, i.e. $b \geq 2$*"

where each character is represented by an integer of certain cardinality.  So basically a $2$ integer array is the minimum.

However say I want to encrypt a single input integer but restrict it to a certain range.  For example say the cardinality of the integer was $2000$ (so the range of possible values from $0 - 1999$).

Can this be done using BPS?  (i.e. Would it be acceptable to simply input an integer array of size one to the algorithm with the cardinality as the range I want?)

I am trying to encrypt a year, but in a way that does not result in a year greater than current year.