How can I get the x LSBs from a string (str) in Python?

In the specific I have a 256 bits string consisting in 32 chars each occupying 1 byte, from wich i have to get a "char" string with the 50 Least Significant Bits.

解决方案

I think that a possible answer could be in this function:

mystr holds my string

def get_lsbs_str(mystr):

chrlist = list(mystr)

result1 = [chr(ord(chrlist[-7])&(3))]

result2 = chrlist[-6:]

return "".join(result1 + result2)

this function take 2 LSBs of the -7rd char of mystr (these are the 2 MSBs of the 50 LSBs)

then take the last 6 characters of mystr (these are the 48 LSB of the 50 LSB)

Please make me know if I am in error.