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Spam and Flags CTF 2019 Teaser - QuadHash
#-*- coding:utf-8 -*-
from common import *
def extend(alg, prefhashes):
if alg == 0:
prefhash = prefhashes[alg]
table = {}
seen = set()
while True:
s = gen()
if s in seen: continue
seen.add(s)
h = mdhash_blocks(s, alg, prefhash)
if h in table:
sb = table[h]
return s, sb, (h,)
else:
table[h] = s
pools = [
{prefhashes[alg]: ()}
]
while True:
pool2 = {}
# find one
for h, s in pools[-1].items():
break
ta, tb, loprefhashes = extend(alg-1, prefhashes)
for h, s in pools[-1].items():
for t in (ta, tb):
hx = mdhash_blocks(t, alg, h)
if hx in pool2:
ha, ta = pool2[hx]
hb = h
tb = t
sa = [ta]
sb = [tb]
while len(pools) > 1:
ha, ta = pools[-1][ha]
hb, tb = pools[-1][hb]
sa.append(ta)
sb.append(tb)
pools.pop()
return "".join(sa[::-1]), "".join(sb[::-1]), loprefhashes + (hx,)
else:
pool2[hx] = h, t
pools.append(pool2)
prefhashes = loprefhashes
if alg >= 2:
print "===" * (3-alg), len(pools)
s1, s2, prefhashes = extend(3, CS)
open("col1", "w").write(s1)
open("col2", "w").write(s2)
print s1, "%08x %08x %08x %08x" % (mdhash_blocks(s1, 0, CS[0]), mdhash_blocks(s1, 1, CS[1]), mdhash_blocks(s1, 2, CS[2]), mdhash_blocks(s1, 3, CS[3]))
print s2, "%08x %08x %08x %08x" % (mdhash_blocks(s2, 0, CS[0]), mdhash_blocks(s2, 1, CS[1]), mdhash_blocks(s2, 2, CS[2]), mdhash_blocks(s2, 3, CS[3]))
print " ".join("%08x" % h for h in prefhashes)
# 11 minutes
# SaF{h3y_sMAlL_inNEr_sT4Te_i5_w0rSE_w1th_enCRYpt1On}
#-*- coding:utf-8 -*-
from random import *
import ctypes
lib = ctypes.cdll.LoadLibrary("./problem.so")
def mdhash_alg(s, alg):
return lib.hash_full(s, len(s), alg)
CS = 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476
def mdhash_block(s, alg, c):
# assert len(s) == 64
return lib.hash_block(s, c, alg)
def mdhash_blocks(s, alg, c):
assert len(s) & 63 == 0
return lib.hash_blocks(s, len(s), c, alg)
N1 = 9
N2 = 2
S1 = "apple, cider, elite,".split()
S2 = "bear, deer,".split()
def pregen():
res = []
for i in xrange(N1):
res.append(choice(S1))
for i in xrange(N2):
res.append(choice(S2))
shuffle(res)
return "".join(res)
print "pregen..."
pool = list({pregen() for i in xrange(2**22)})
print "done"
def gen():
return choice(pool)
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