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# Rev80 - Eso Tape

## Description

I once took a nap on my keyboard. I dreamed of a brand new language, but I could not decipher it nor get its meaning. Can you help me? Hint: Replace the spaces with either '{' or '}' in the solution. Hint: Interpreters don't help. Operations write to the current index.

## Solution

With a bit of research we found out that the programming language used in this challenge is called TapeBagel.

This is the program reversed.


## resets all of the integers to zero
%% resets the integer index to zero
%++ i[0]++
%++ i[0]++
%++ i[0] = 3
%# i[1]
*&* i[1] = 9
@** print i[1] -> 9 -> I
%# i[2]
**&* i[2] = i[0]*i[1] = 27
***-* i[2] = i[2] - i[0] = 24
***-* i[2] = 21
%++ i[2]++
%++ i[2]++
@*** print i[2] -> 21 -> W
*-* i[2] = 0
@*** print i[2] -> ' ' -> {
@** print i[1] -> 9 -> I
*+** i[2] = i[1] + i[0] = 12
@*** print i[2] -> 12 -> L
***+* i[2] = i[2] + i[0] = 12 + 3 = 15
@*** print i[2] -> 15 -> O
**+** i[2] = i[1] + i[1] = 18
***+* i[2] = i[2] + i[0] = 21
%++ i[2]++
@*** print i[2] -> 22 -> V
#% sets all the integers to one
%% resets the integer index to zero
%++ i[0]++
%++ i[0]++
%++ i[0]++
%++ i[0]++ -> i[0] = 5
@* print i[0] -> 5 -> E
%# adds one to the integer index
%++ i[1]++
%++ i[1]++
%++ i[1]++ -> i[1] = 4
%% resets the integer index to zero
*&** i[0] = i[0] * i[1] = 20
@* print i[0] -> 20 -> T
@*** print i[2] -> 1 -> A
*-** i[0] = i[0] - i[1] = 16
@* print i[0] -> 16 -> P
%# adds one to the integer index
%++ i[1]++ -> i[1] = 5
@** print i[1] -> 5 -> E
*-** i[1] = i[0] - i[1] = 11
*-** i[1] = i[0] - i[1] = 5
**-*** i[1] = i[1] - i[2] = 4
**-*** i[1] = i[1] - i[2] = 3
**-*** i[1] = i[1] - i[2] = 2
@** print i[1] -> 2 -> B
@*** print i[2] -> 1 -> A
#% sets all the integers to one
%% resets the integer index to zero
%++ i[0]++
%++ i[0]++
%++ i[0]++
%++ i[0]++ -> i[0] = 5
%# adds one to the integer index
*+** i[1] = i[0] + i[1] = 6
%++ i[1]++ -> i[1] = 7
@** print i[1] -> 7 -> G
@* print i[0] -> 5 -> E
%# adds one to the integer index
*+** i[2] = i[0] + i[1] = 12
@*** print i[2] -> 12 -> L
## resets all of the integers to zero
%% resets the integer index to zero
@*** print i[2] -> 0 -> ' '


In the end, ~~it doesn't even~~ the flag is IW{ILOVETAPEBAGEL}

Original writeup (https://github.com/QuokkaLight/write-ups/blob/master/internetwache-ctf-2016/reverse/rev80.md).