bits 64
global _start

_start:
		push rbp
		push rsp
		push rbx
		push r12
		push r13
		push r14
		push r15

		mov rdi, 1
		lea     rsi, [rel msg]
		mov rbx, rsi
		sub rbx, qword [rel text_section] ;text_section address because of this and that
		mov r8, qword [rel section_size] ;text_section size
		shr r8, 2
		inc r8
		inc r8
		inc r8
		inc r8
		mov r9, 0 ;increment register
		mov r10, 0 ;increment register
		xor r10, r10
		xor r13, r13
		mov r13d, dword [rel private_key]
		xor r12, r12
		mov r12d, dword [rel private_key + 4]
		;shr r12, 32
		push r13 ; push rsa.d
		push r12 ; push rsa.n
		jmp decrypt_loop

	; rbx is adress of text(encrypted) section
	; r8 is section size
	; r9 is index
	; rax is cypher that needs to be converted to message
	; dword [rsp + 16] is rsa.d
	; dword [rsp + 8] is rsa.n
	; qword [rsp] is cypher backup
	decrypt_once:
		mov r11, 0x100000000
	sq_mul_bit_index:
		shr r11, 1
		mov r12, r11
		and r12, qword [rsp + 16]
		jz sq_mul_bit_index
	sq_mul_loop:
		shr r11, 1
		cmp r11, 0
		je decrypt_loop2
		mul rax,
		; modulo n ...
		mov r13, qword [rsp + 8]
		xor rdx, rdx
		div r13
		mov rax, rdx
		; modulo n ...
		mov r12, r11
		and r12, qword [rsp + 16]
		cmp r12, 0
		je sq_mul_loop
		mov r13, qword [rsp]
		mul r13
		; modulo n ...
		mov r13, qword [rsp + 8]
		xor rdx, rdx
		div r13
		mov rax, rdx
		; modulo n ...
		jmp sq_mul_loop

	decrypt_loop:
		cmp r8, r10
		je end_decrypt
		xor rax, rax
		mov eax, dword [rbx + r9]
		push rax
		;push r10
		jmp decrypt_once
	decrypt_loop2:
		sub rax, 42 ; remove 42 of result (avoid 0 values)
		sub rax, r10 ; remove index of result (caesar like cypher so 0/42 values are differents)
		; unpadding and write back here
		mov dword [rbx + r9], 0
		mov rcx, r10
		mov r15, r10
		shr r15, 5
		shl r15, 2
		inc rcx
		shl rcx, 59
		shr rcx, 59
		shl rax, cl
		mov r14, r9
		sub r14, r15
		add [rbx + r14], eax
		mov rcx, rax
		shr rcx, 32
		cmp r9, 0
		je first_block_skip
		add [rbx + r14 - 4], ecx

	first_block_skip:
		; unpadding and write back here
		pop rax
		add r9, 4
		inc r10
		jmp decrypt_loop

	end_decrypt:
		mov rdx, 14
		mov rax, 1
		syscall

		pop r12 ; pop rsa.n
		pop r12 ; pop rsa.d

		pop r15
		pop r14
		pop r13
		pop r12
		pop rbx
		pop rsp
		pop rbp

        jmp 0xdadadada ; this needs to be just before that
		msg     db "....WOODY....",10 ; that needs to be just after this
		text_section      dq 0xbabababababababa
		section_size     dq 0xcacacacacacacaca
		private_key       dq 0xabcdefabcdefabcd