#!/usr/bin/python

# Repeatedly run a sha256 on random data.  Keeps a rolling buffer of the last
# <buflen> hashes and re-checks them.  Prints an error ONLY if a mismatch is
# found.  If a mismatch is found, you have a hardware problem.

from hashlib import sha256
from collections import deque
import random

buflen = 100000
hashbuf = deque(maxlen=buflen)

for i in range(buflen):
    hashbuf.append([str(i), sha256(str(i)).hexdigest()])

while True:
    k, khash = hashbuf.popleft()
    pophash = sha256(k).hexdigest()
    if pophash != khash:
        print "ERROR: sha256(%s) = %s does not match:"%(k, khash)
        print "       sha256(%s) = %s"%(k, pophash)
    k = str(random.getrandbits(1000))
    khash = sha256(k).hexdigest()
    hashbuf.append([k, khash])