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fix megalosaure path and remove legacy solver code

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Signed-off-by: Julien CLEMENT <julien.clement@epita.fr>
This commit is contained in:
Julien CLEMENT 2024-04-15 10:59:53 +02:00
parent 35e083d2d3
commit ac5a0ab6fd
2 changed files with 2 additions and 56 deletions
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2
jujure/content/writeups/fcsc_2024/megalosaure.md
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@ -29,7 +29,7 @@ Author: `Cryptanalyse`
## Given files
[megalosaure](/megalosaure/megalosaure)
[megalosaure](/megalosaure/src/megalosaure)
# Writeup

56
jujure/static/megalosaure/src/disasm.py
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@ -4,7 +4,7 @@ import struct
from pwn import *
from typing import Optional, List
from Crypto.Util.number import inverse
from z3 import *
#from z3 import *
opcodes = {
@ -210,7 +210,6 @@ class Child:
self.depends = []
self.unlocks = []
self.inputs = []
self.forced = False, 0
self.main_instr = None
while True:
instr = Instruction.disassemble(self.code)
@ -255,59 +254,6 @@ class Child:
for unlock in self.unlocks:
locks[unlock] = (False, self)
def invert(self, desired):
instr = self.main_instr
op = instr.name
inputs = self.inputs
if len(inputs) == 0:
if op == 'push_m':
return desired
elif op == 'push32_i_i':
print(self.forced)
raise
else:
print(op)
elif len(inputs) == 1:
inp = inputs[0]
if op == "pop_m":
return inp.invert(desired)
if op == "not":
return inp.invert((~desired) % N)
else:
print(op)
else:
forced0 = inputs[0].forced
forced1 = inputs[1].forced
if not forced0 and not forced1:
return
forced_child = inputs[0] if forced0[0] else inputs[1]
unk_child = inputs[1] if forced0[0] else inputs[0]
if op == 'xor':
return unk_child.invert(desired ^ forced_child.forced[1])
elif op == 'sub':
if forced0:
return unk_child.invert((desired + forced_child.forced[1]) % N)
else:
return unk_child.invert((-desired + forced_child.forced[1]) % N)
elif op == 'add':
return unk_child.invert((desired - forced_child.forced[1]) % N)
elif op == 'and':
return unk_child.invert(desired & forced_child.forced[1])
elif op == 'or':
return unk_child.invert(desired | forced_child.forced[1])
elif op == 'mul':
return unk_child.invert(((desired) * inverse(forced_child.forced[1], N)) % N)
elif op == 'shl':
return unk_child.invert(((desired) * inverse(forced_child.forced[1], N)) % N)
else:
print(op)
def transpile(self, indent=0):
code = "(\n"
indent += 4