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joekir/MurmurHash3Test.java

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README.md

Running the example

Modify the Java code in main in MurmurHash3Test.java to whatever you want, including the seed const. Seed recovery has already been proven here - https://www.131002.net/siphash/poc.py

  byte[] data = { 90, 1, 2, 44};
  System.out.format("0x%x\n", murmurhash3_x86_32(data, 0, data.length, 0xefef));
$ mkdir -p {src,target}
$ mv MurmurHash3Test.java src/
$ chmod +x buildnrun.sh inverter.py
$ ./buildnrun.sh | ./inverter.py 4
sat

inverting 0x4642c344 returns:
[0, 90]
[2, 2]
[1, 1]
[3, 44]
Raw
buildnrun.sh
#!/bin/bash
javac -d target/ src/*
cd target
java MurmurTest
cd ../
Raw
inverter.py
#!/usr/bin/python2.7
from z3 import *
import sys
"""
See https://raw.githubusercontent.com/yonik/java_util/master/src/util/hash/MurmurHash3.java
for implementation of the code modelled below
The one downside is that the logic is so complex in some of the switch statements below
that I had to concretize the length of the input data array, this is ok as usually you can
iteratively tune this until you get meaningful plaintext inputs, or it follows a fixed schema, etc.
"""
def dk(i):
return "k"+str(i)
def dh(i):
return "h"+str(i)
def solve():
s = SolverFor("BV")
s.set("local_ctx",True)
# Concrete
roundedEnd = length & 0xfffffffc
c1 = 0xcc9e2d51
c2 = 0x1b873593
seed = 0xefef # this is fixed in the impl I'm looking into
# Based on array theory, maps an Int32 to a Byte
data = Array('data', BitVecSort(32), BitVecSort(8))
kvecs = {}
hvecs = {}
# ha and ka are allocation counters for each map
ka = 0
ha = 0
# init hvecs to seed
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == seed)
ha += 1
i=0
while i < roundedEnd:
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == ((SignExt(24,data[i]) & 0xff) | ((SignExt(24,data[i+1]) & 0xff) << 8) | ((SignExt(24,data[i+2]) & 0xff) << 16) | (SignExt(24, data[i+3]) << 24)))
ka += 1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == kvecs[dk(ka-1)] * c1)
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == ((kvecs[dk(ka-1)] << 15) | LShR(kvecs[dk(ka-1)],17)))
ka += 1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == kvecs[dk(ka-1)] * c2)
ka +=1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == (hvecs[dh(ha-1)] ^ kvecs[dk(ka-1)]))
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == ((hvecs[dh(ha-1)] << 13) | LShR(hvecs[dh(ha-1)],19)))
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == ((hvecs[dh(ha-1)] * 5) + 0xe6546b64))
ha += 1
i += 4
# had to concretize this as the logic (ROT32) in the `switch == 1`
# statement below cannot be inlined to the z3.If statement
# SSA means lots of duplication here, sorry..
switch = length & 3
if switch == 3:
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == ((SignExt(24,data[roundedEnd + 2]) & 0xff) << 16))
ka += 1
# fallthrough 1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] | ((SignExt(24,data[roundedEnd + 1]) & 0xff) << 8)))
ka +=1
# fallthrough 2
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] | (SignExt(24,data[roundedEnd]) & 0xff)))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] * c1))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == ((kvecs[dk(ka-1)] << 15) | LShR(kvecs[dk(ka-1)],17)))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] * c2))
ka +=1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == (hvecs[dh(ha-1)] ^ kvecs[dk(ka-1)]))
ha += 1
if switch == 2:
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == ((SignExt(24,data[roundedEnd + 1]) & 0xff) << 8))
ka +=1
# fallthrough 2
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] | (SignExt(24,data[roundedEnd]) & 0xff)))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] * c1))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == ((kvecs[dk(ka-1)] << 15) | LShR(kvecs[dk(ka-1)],17)))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] * c2))
ka +=1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == (hvecs[dh(ha-1)] ^ kvecs[dk(ka-1)]))
ha += 1
if switch == 1:
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (SignExt(24,data[roundedEnd]) & 0xff))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] * c1))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == ((kvecs[dk(ka-1)] << 15) | LShR(kvecs[dk(ka-1)],17)))
ka +=1
kvecs[dk(ka)] = BitVec(dk(ka),32)
s.add(kvecs[dk(ka)] == (kvecs[dk(ka-1)] * c2))
ka +=1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == (hvecs[dh(ha-1)] ^ kvecs[dk(ka-1)]))
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == (hvecs[dh(ha-1)] ^ length))
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == LShR(hvecs[dh(ha-1)],16))
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == hvecs[dh(ha-2)] ^ hvecs[dh(ha-1)])
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == (hvecs[dh(ha-1)] * 0x85ebca6b))
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == LShR(hvecs[dh(ha-1)],13))
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == hvecs[dh(ha-2)] ^ hvecs[dh(ha-1)])
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == (hvecs[dh(ha-1)] * 0xc2b2ae35))
ha += 1
hvecs[dh(ha)] = BitVec(dh(ha),32)
s.add(hvecs[dh(ha)] == LShR(hvecs[dh(ha-1)],16))
ha += 1
s.add(hash_result == hvecs[dh(ha-2)] ^ hvecs[dh(ha-1)])
ch = s.check()
print ch
if ch.r == 1:
model = s.model()
print "\ninverting 0x%x returns:" % hash_result
data = model[data]
for i in range(0 ,length):
print data.entry(i)
else:
print s.unsat_core()
# should really use proper argparse here, but lazy
if not sys.stdin.isatty():
# piped from build output
hash_result = int(sys.stdin.read(),0)
length = int(sys.argv[1])
elif len(sys.argv) != 3:
print "Sorry, calling format has to be like ./inverter.py 0x(<murmurhash>) original_data_length"
sys.exit(1)
else:
# just called directly
hash_result = int(sys.argv[1],0)
length = int(sys.argv[2])
solve()
Raw
MurmurHash3Test.java
class MurmurTest {
public static void main(String args[]){
byte[] data = { 90, 1, 2, 44};
System.out.format("0x%x\n", murmurhash3_x86_32(data, 0, data.length, 0xefef));
}
/*
* This is verbatim from:
* https://raw.githubusercontent.com/yonik/java_util/master/src/util/hash/MurmurHash3.java
*/
public static int murmurhash3_x86_32(byte[] data, int offset, int len, int seed) {
int c1 = 0xcc9e2d51;
int c2 = 0x1b873593;
int h1 = seed;
int roundedEnd = offset + (len & 0xfffffffc); // round down to 4 byte block
for (int i=offset; i<roundedEnd; i+=4) {
// little endian load order
int k1 = (data[i] & 0xff) | ((data[i+1] & 0xff) << 8) | ((data[i+2] & 0xff) << 16) | (data[i+3] << 24);
k1 *= c1;
k1 = (k1 << 15) | (k1 >>> 17); // ROTL32(k1,15);
k1 *= c2;
h1 ^= k1;
h1 = (h1 << 13) | (h1 >>> 19); // ROTL32(h1,13);
h1 = h1*5+0xe6546b64;
}
// tail
int k1 = 0;
switch(len & 0x03) {
case 3:
k1 = (data[roundedEnd + 2] & 0xff) << 16;
// fallthrough
case 2:
k1 |= (data[roundedEnd + 1] & 0xff) << 8;
// fallthrough
case 1:
k1 |= (data[roundedEnd] & 0xff);
k1 *= c1;
k1 = (k1 << 15) | (k1 >>> 17); // ROTL32(k1,15);
k1 *= c2;
h1 ^= k1;
}
// finalization
h1 ^= len;
// fmix(h1);
h1 ^= h1 >>> 16;
h1 *= 0x85ebca6b;
h1 ^= h1 >>> 13;
h1 *= 0xc2b2ae35;
h1 ^= h1 >>> 16;
return h1;
}
}
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