How to get a unique key from unicode string in php -

How to get a unique key from unicode string in php -

i have many unicode strings , want store them in mysql db. want add together field such represents character identity of string. example:

string key ------ ----------- 1st string 113547858 first string 113547865 go school 524872354

as may have noticed above, first 2 keys close each other, representing strings similarity, whereas 3rd 1 far them. dont want utilize php's similar_text or levenshtein need 2 strings check similarity, want store value each single string store in db in order set index on future use.

any help?!

simple addition of character codes of characters of string can solution?

update:

summation of hash value @ level of every word of string can solution

php string similarity levenshtein-distance