How to hash a string into 8 digits?

Yes, you can use the built-in hashlib module or the built-in hash function. Then, chop-off the last eight digits using modulo operations or string slicing operations on the integer form of the hash:

>>> s="she sells sea shells by the sea shore"

>>> # Use hashlib
>>> import hashlib
>>> int(hashlib.sha1(s.encode("utf-8")).hexdigest(), 16) % (10 ** 8)
58097614L

>>> # Use hash()
>>> abs(hash(s)) % (10 ** 8)
82148974