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synacor.py/tools/generate_codes.py

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#!/usr/bin/env python3
# synacor.py - An implementation of the Synacor Challenge
# Copyright © 2017 RunasSudo
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import struct
import sys
IV_LEN = 3
CODE_LEN = 12
def generate_code(R1, R2, R3, R4):
R2data = SYN_MEM[R2+1:R2+1+SYN_MEM[R2]]
R4data = SYN_MEM[R4+1:R4+1+SYN_MEM[R4]]
assert len(R4data) == IV_LEN
done = False
while not done:
code = ''
for i in range(CODE_LEN):
R6 = i % IV_LEN
R7 = R4data[R6]
R7 = (R7 * 0x1481) % 0x8000
R7 = (R7 + 0x3039) % 0x8000
R4data[R6] = R7
R7 = R1 ^ R7
R7 = R7 % len(R2data)
if R7 + 1 <= R3:
done = True
R7 = R2data[R7]
code += chr(R7)
return code
# Read code into memory
SYN_MEM = [0] * 32768
with open(sys.argv[1], 'rb') as data:
i = 0
while True:
byteData = data.read(2)
if len(byteData) < 2:
break
SYN_MEM[i] = struct.unpack('<H', byteData)[0]
i += 1
# Emulate 06bb
for R2 in range(0x17b4, 0x7562):
R1 = SYN_MEM[R2]
R1 ^= pow(R2, 2, 32768)
R1 ^= 0x4154
SYN_MEM[R2] = R1
# Look for calls to 0731
CODE_PARAMS = [
(0x0058, 0x650a, 0x7fff, 0x6e8b), # R1 from the maze
(0x1092, 0x650a, 0x7fff, 0x6eed),
(0x6486, 0x650a, 0x7fff, 0x7239), # R1 is R8 from Ackermann
# 162e is a bit tricky
# 1691 is a bit tricky
]
for cp in CODE_PARAMS:
print(generate_code(*cp))