>>>I'd like to create a hash (i.e. non-reversible) from a SSN that is at least the same length as a SSN. A checksum only gives you 4 digits. I tried a hash function in the cryptapi class but it was a bunch of odd characters.

To get rid of the "odd characters" (i.e. binary) you change it to Base 64.

Check out the STRCONV(cText,13) function.