Metasm

Metasm is a cross-architecture assembler, disassembler, linker, and debugger. It is written in such a way that it is easy to add support for new architectures. For now, the following architectures are in:

• Intel Ia32.txt (16 and 32bits)
• Intel X86_64.txt (aka Ia32 64bits, X64, AMD64)
• MIPS
• PowerPC
• Sh4

Supports low and high-level debugging support (Ia32 only for now) under Windows, Linux and remote (via a gdbserver). Metasm is included in Metasploit by default.

• To install Metasm

  gem install metasm
  

  More about installation here.

1. Converting Assembly to Op-code - metasm-shell.rb

You can find metasm-shell in ruby gems default path after installation. In my case, it's located in /var/lib/gems/2.1.0/gems/metasm-1.0.2/samples

• Run it

ruby metasm-shell.rb 
type "exit" or "quit" to quit
use ";" for newline

asm>

as you can see you are now in the shell's prompt

• Find assembly op-code

asm> nop nop
"\x90\x90"
asm> call [eax]
"\xff\x10"
asm> push esp
"\x54"
asm> pop eax
"\x58"

More usage will be added for this awesome library.

2.