172 lines
4.1 KiB
Python
Executable File
172 lines
4.1 KiB
Python
Executable File
#!/usr/bin/env python3
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import argparse
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import sys
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LONG_KEY = (
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0x6c, 0x1b, 0x99, 0x5f, 0xb9, 0xcd, 0x5f, 0x13,
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0xcb, 0x04, 0x20, 0x0e, 0x5e, 0x1c, 0xa1, 0x0e,
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)
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OTHER_LONG_KEY = (
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0x67, 0xa8, 0xd6, 0x26, 0xb6, 0xdd, 0x45, 0x1b,
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0x32, 0x7e, 0x22, 0x13, 0x15, 0xc2, 0x94, 0x37,
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)
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class Byte:
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def __init__(self, v: int):
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self.v = v & 0xff
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def __add__(self, v: int):
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return Byte(self.v + v)
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def __iadd__(self, v: "Byte"):
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self.v = (self.v + v) & 0xff
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return self
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def __sub__(self, v: int):
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return Byte(self.v - v)
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def __isub__(self, v: "Byte"):
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self.v = (self.v - v) & 0xff
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return self
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def __mod__(self, v: int):
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return Byte(self.v % v)
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def __imod__(self, v: int):
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self.v %= v
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return self
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def __xor__(self, v: int):
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return Byte(self.v ^ v)
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def __ixor__(self, v: int):
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self.v = (self.v ^ v) & 0xff
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return self
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def __and__(self, v: int):
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return Byte(self.v & v)
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def __iand__(self, v: int):
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self.v = (self.v & v) & 0xff
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return self
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def __eq__(self, other):
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if isinstance(other, Byte):
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return self.v == other.v
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elif isinstance(other, int):
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return self.v == (other & 0xff)
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raise ValueError(f"Object {other:r} of invalid type {type(other)}")
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def __repr__(self):
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return f"(byte 0x{self.v:02x})"
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def decode_line(line: bytes, method: int) -> bytes:
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line = line.rstrip(b"\r\n")
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key = LONG_KEY
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seed = len(line) % len(key)
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dline = bytearray(len(line))
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for i, c in enumerate(line):
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b = Byte(c)
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if dline[i - 2:i] == b'//':
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key = OTHER_LONG_KEY
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if method == 1:
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if b == ord(b'\t'):
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b = Byte(0x9f)
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b -= 0x20
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b ^= key[seed]
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b &= 0x7f
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b += 0x20
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seed += 7
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seed %= len(key)
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if b == 0x9f:
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b = Byte(ord(b'\t'))
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else:
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if b == ord(b'\t'):
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b = Byte(0x80)
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b -= 0x20
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if (b & 0x80) == 0:
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b ^= key[seed] & 0x7f
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b += 0x20
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seed += 7
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seed %= len(key)
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if b == 0x80:
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b = Byte(ord(b'\t'))
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dline[i] = b.v
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return dline
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def encode_line(line: bytes, method: int) -> bytes:
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line = line.rstrip(b"\r\n")
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key = LONG_KEY
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seed = len(line) % len(key)
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count = 0
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eline = bytearray(len(line))
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for i, c in enumerate(line):
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if count == 2:
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key = OTHER_LONG_KEY
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if c == ord('/'):
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count += 1
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else:
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count = 0
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if method == 1:
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if c == ord('\t'):
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c = 0x9f
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b = Byte(c)
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b -= 0x20
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b ^= key[seed]
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b &= 0x7f
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b += 0x20
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seed += 7
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seed %= len(key)
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if b == 0x9f:
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b = Byte(ord('\t'))
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else:
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if c == ord('\t'):
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c = 0x80
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b = Byte(c - 0x20)
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if (b & 0x80) == 0:
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b ^= key[seed] & 0x7f
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b += 0x20
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seed += 7
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seed %= len(key)
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if b == 0x80:
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b = Byte(ord('\t'))
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eline[i] = b.v
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return bytes(eline)
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def main():
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parser = argparse.ArgumentParser(allow_abbrev=False, description="Decode/encode a Carmageddon text file")
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parser.add_argument("file", metavar="FILE", nargs="?", help="input file (default=stdin)")
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parser.add_argument("--method", choices=[1, 2], type=int, default=2, help="encryption method to use (default=2)")
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args = parser.parse_args()
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istream = open(args.file, "rb") if args.file else sys.stdin.buffer
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for line in istream.readlines():
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if line[0] == ord(b'@'):
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dline = decode_line(line[1:], args.method)
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sys.stdout.buffer.write(dline)
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else:
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eline = b"@" + encode_line(line, args.method)
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sys.stdout.buffer.write(eline)
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sys.stdout.buffer.write(b'\n')
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if __name__ == "__main__":
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raise SystemExit(main())
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