# -*- coding: binary -*-

require 'rex/encoder/alpha2/generic'

module Rex
module Encoder
module Alpha2

class UnicodeUpper < Generic
  def self.default_accepted_chars ; ('B' .. 'Z').to_a + ('0' .. '9').to_a ; end

  def self.gen_second(block, base)
    # unicode uses additive encoding
    (block - base)
  end

  def self.gen_decoder_prefix(reg, offset)
    if (offset > 6)
      raise "Critical: Offset is greater than 6"
    end

    # offset untested for unicode :(
    if (offset <= 4)
      nop = 'CP' * offset
      mod = 'IA' * (4 - offset) + nop    # dec ecx,,, push ecx, pop edx
    else
      mod = 'AA' * (offset - 4)          # inc ecx
      nop = 'CP' * (4 - mod.length)
      mod += nop
    end

    regprefix = {                      # nops ignored below
      'EAX'   => 'PPYA' + mod,        # push eax, pop ecx
      'ECX'   =>  mod + '4444',       # dec ecx
      'EDX'   => 'RRYA' + mod,        # push edx, pop ecx
      'EBX'   => 'SSYA' + mod,        # push ebx, pop ecx
      'ESP'   => 'TUYA' + mod,        # push esp, pop ecx
      'EBP'   => 'UUYA' + mod,        # push ebp, pop ecx
      'ESI'   => 'VVYA' + mod,        # push esi, pop ecx
      'EDI'   => 'WWYA' + mod,        # push edi, pop edi
      '[ESP]' => 'YA' + mod + '44',   #
      '[ESP+4]' => 'YUYA' + mod,      #
    }

    return regprefix[reg]
  end

  def self.gen_decoder(reg, offset)
    decoder =
      gen_decoder_prefix(reg, offset) +
      "QA" +                  # push ecx, NOP
      "TA" +                  # push esp, NOP
      "XA" +                  # pop eax, NOP
      "ZA" +                  # pop edx, NOP
      "PU" +                  # push eax, NOP
      "3" +                   # xor eax, [eax]
      "QA" +                  # push ecx, NOP
      "DA" +                  # inc esp, NOP
      "ZA" +                  # pop edx, NOP
      "BA" +                  # inc edx, NOP
      "RA" +                  # push edx, NOP
      "LA" +                  # dec esp, NOP
      "YA" +                  # pop ecx, NOP
      "IA" +                  # dec ecx, NOP
      "QA" +                  # push ecx, NOP
      "IA" +                  # dec ecx, NOP
      "QA" +                  # push ecx, NOP
      "PA" +                  # push eax, NOP
      "5AAA" +                # xor eax, 41004100 - NOP
      "PA" +                  # push eax, NOP
      "Z" +                   # pop edx
      "1A" +                  # add [ecx], dh - NOP
      "I" +                   # dec ecx
      "1A" +                  # add [ecx], dh - NOP
      "IA" +                  # dec ecx, NOP
      "IA" +                  # dec ecx, NOP
      "J" +                   # dec edx
      "1" +                   # add [ecx], dh
      "1A" +                  # add [ecx], dh - NOP
      "IA" +                  # dec ecx, NOP
      "IA" +                  # dec ecx, NOP
      "XA" +                  # pop eax, NOP
      "58AA" +                # xor eax, 41003800 - NOP
      "PA" +                  # push eax, NOP
      "ZA" +                  # pop edx, NOP
      "BA" +                  # inc edx, NOP
      "B" +                   # inc edx
      "Q" +                   # add [ecx], dl
      "I" +                   # dec ecx
      "1A" +                  # add [ecx], dh - NOP
      "I" +                   # dec ecx
      "Q" +                   # add [ecx], dl
      "IA" +                  # dec ecx, NOP
      "I" +                   # dec ecx
      "Q" +                   # add [ecx], dl
      "I" +                   # dec ecx
      "1" +                   # add [ecx], dh
      "1" +                   # add [ecx], dh
      "1" +                   # add [ecx], dh
      "1A" +                  # add [ecx], dh - NOP
      "IA" +                  # dec ecx, NOP
      "J" +                   # dec edx
      "Q" +                   # add [ecx], dl
      "I" +                   # dec edx
      "1A" +                  # add [ecx], dh - NOP
      "YA" +                  # pop ecx, NOP
      "ZB" +                  # pop edx, NOP
      "AB" +                  # inc ecx, NOP      <-------
      "AB" +                  # inc ecx, NOP              |
      "AB" +                  # inc ecx, NOP              |
      "AB" +                  # inc ecx, NOP              |
      "30" +                  # imul eax, [ecx], 10 *     |
      "A" +                   # add al, [ecx+2] *         |
      "P" +                   # mov [edx], al *           |
      "B" +                   # inc edx                   |
      "9" +                   # cmp [ecx], 41 *           |
      "4" +                   # jnz   --------------------
      "4JB"

    return decoder
  end

end end end end