# Test specific IV candidates

Code.require_file("lib/odinsea/util/bit_tools.ex", ".")
Code.require_file("lib/odinsea/net/cipher/ig_cipher.ex", ".")
Code.require_file("lib/odinsea/net/cipher/aes_cipher.ex", ".")
Code.require_file("lib/odinsea/net/cipher/shanda_cipher.ex", ".")

alias Odinsea.Net.Cipher.{IGCipher, AESCipher, ShandaCipher}

import Bitwise

packet = <<0x7C, 0xA8, 0x7B, 0xA8, 0xBF, 0x0A, 0xCD, 0xDE, 0xC7, 0x71, 0xAC>>
<<raw_seq::little-16, raw_len::little-16, payload::binary>> = packet

IO.puts("Testing IV candidates for packet: #{Base.encode16(packet)}")
IO.puts("raw_seq: 0x#{Integer.to_string(raw_seq, 16)}, raw_len: 0x#{Integer.to_string(raw_len, 16)}")
IO.puts("")

# IV candidates based on bytes [2]=0x0F, [3]=0x0C, [4]=0xA8, [5]=0xBC
candidates = [
  <<0x0F, 0x0C, 0x0C, 0xA8>>,  # [2][3][3][4] - overlapping
  <<0x0C, 0x0C, 0x0C, 0xA8>>,  # [3][3][3][4]
  <<0x0C, 0xA8, 0x0C, 0xA8>>,  # [3][4][3][4] - repeating pattern
  <<0x0F, 0x0C, 0xA8, 0xBC>>,  # [2][3][4][5] - recv_iv from hello?
  <<0x34, 0x9A, 0x0C, 0xA8>>,  # [0][1][3][4]
  <<0x9A, 0x0F, 0x0C, 0xA8>>,  # [1][2][3][4]
  <<0x0C, 0xA8, 0xBC, 0x0D>>,  # [3][4][5][6]
  <<0xA8, 0xBC, 0x0C, 0xA8>>,  # [4][5][3][4]
]

Enum.each(candidates, fn iv ->
  <<_r0, _r1, r2, r3>> = iv
  seq_base = ((r2 &&& 0xFF) ||| ((r3 <<< 8) &&& 0xFF00)) &&& 0xFFFF
  valid = bxor(raw_seq &&& 0xFFFF, seq_base) == 112
  
  IO.puts("IV: #{Base.encode16(iv)}")
  IO.puts("  seq_base: 0x#{Integer.to_string(seq_base, 16)}, valid: #{valid}")
  
  if valid do
    # Try full decryption
    aes_result = AESCipher.crypt(payload, iv)
    shanda_result = ShandaCipher.decrypt(aes_result)
    
    if byte_size(shanda_result) >= 2 do
      <<opcode::little-16, _rest::binary>> = shanda_result
      IO.puts("  *** VALID IV! ***")
      IO.puts("  Decrypted opcode: 0x#{Integer.to_string(opcode, 16)} (#{opcode})")
      if opcode == 1 do
        IO.puts("  *** CORRECT OPCODE! ***")
      end
    end
  end
  
  IO.puts("")
end)