STINNER Victor <[email protected]> added the comment:
Paul first proposition (on python-dev) was to replace:
...
x = (ord(s[0]) << 7)
while i < length:
x = intmask((1000003*x) ^ ord(s[i]))
...
by:
...
x = (ord(s[0]) << 7)
while i < length:
x = intmask((1000003*x) ^ ord(s[i])) ^ r[x % len_r]
...
This change has a vulnerability similar than the one of Christian's suggested
changed. The "r" array can be retreived directly with:
r2 = []
for i in xrange(len(r)):
s = chr(intmask(i * UNSHIFT7) % len(r))
h = intmask(hash(s) ^ len(s) ^ ord(s) ^ ((ord(s) << 7) * MOD))
r2.append(chr(h))
r2 = ''.join(r2)
where UNSHIFT7 = 1/2**7 mod 2^(long bits).
By the way, this change always use r[0] to hash all string of one ASCII
character (U+0000-U+007F).
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Python tracker <[email protected]>
<http://bugs.python.org/issue13703>
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