Difference between revisions of "Gits2012teaser"
From Fixme.ch
(→Hackquest) |
(→#2 AL's Revenge) |
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== #2 AL's Revenge == | == #2 AL's Revenge == | ||
| + | |||
| + | * file 49dd327824d5afe9cdf931ea4b13719f.bin says xz compressed file -> xzcat > f | ||
| + | * file f says LLVM bitcode -> llvm-dis > f.s (only works with LLVM 2.8, not with 3.0) | ||
| + | * analyze disassembly, extract C representation: | ||
| + | |||
| + | <pre> | ||
| + | int | ||
| + | VerifySerial(uint64_t name, uint64_t serial) | ||
| + | { | ||
| + | uint64_t a = 0x8000000000000000LL; | ||
| + | uint64_t b = 0xa348fccd93aea5a7LL; | ||
| + | uint64_t result = 0; | ||
| + | |||
| + | /* high order bit set? */ | ||
| + | if (name & a) | ||
| + | a ^= b; | ||
| + | |||
| + | if (serial & a) | ||
| + | serial ^= b; | ||
| + | |||
| + | while (serial != 0) { | ||
| + | if (serial & 1) | ||
| + | result ^= name; | ||
| + | |||
| + | serial >>= 1; | ||
| + | name <<= 1; | ||
| + | |||
| + | if (name & a) | ||
| + | name ^= b; | ||
| + | } | ||
| + | |||
| + | return (result == 1); | ||
| + | } | ||
| + | </pre> | ||
== #3 Hackquest == | == #3 Hackquest == | ||
Revision as of 13:39, 8 January 2012
#1 TelAviv
#2 AL's Revenge
- file 49dd327824d5afe9cdf931ea4b13719f.bin says xz compressed file -> xzcat > f
- file f says LLVM bitcode -> llvm-dis > f.s (only works with LLVM 2.8, not with 3.0)
- analyze disassembly, extract C representation:
int
VerifySerial(uint64_t name, uint64_t serial)
{
uint64_t a = 0x8000000000000000LL;
uint64_t b = 0xa348fccd93aea5a7LL;
uint64_t result = 0;
/* high order bit set? */
if (name & a)
a ^= b;
if (serial & a)
serial ^= b;
while (serial != 0) {
if (serial & 1)
result ^= name;
serial >>= 1;
name <<= 1;
if (name & a)
name ^= b;
}
return (result == 1);
}
