Hashto_given_weight.py 文件源码

def hash_Dk(s):
    '''
        securely hashes a string s to a length k (= 512) string with 
        64(kappa) many +-1 's.
        This can be extended to other lengths and kappa's. 
        it would be bitwise operations on the binary value of a 
        suitable hash
    '''
    oparray = [0] * 512
    num = bin(int(hashlib.sha256(s).hexdigest(),16))[2:]
    i = 0
    j = 0
    while(i < 256):
        shift8 = int(num[i+1 : i+4], 2)
        if(num[i] == '0'):
            oparray[j + shift8] = 1
        else:
            oparray[j + shift8] = -1

        j += 8
        i += 4

    return oparray