via IRC

blackbox.py

import socket
import random

host = "blackbox_ced7f267475a0299446fa86c26d77161.quals.shallweplayaga.me"
port = 18324

inputs = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!\"#$%&'()*+,-./:;<=>?@[\]^_`{|}~ "

s = socket.socket()
s.connect((host, port))

print s.recv(2048)
print s.recv(2048)

test = "ABab"

# Box 1
s.sendall(test+"\n")

rec = s.recv(2048)

resp = rec[rec.index("[")+1:rec.index("\t")-1]
shift = inputs.index(resp[0])
shift -= inputs.index(test[0])

resp = rec[rec.index("Expected"):]

ans = resp[resp.index("[")+1:-2]

out = ""
for l in ans:
	key = (inputs.index(l)-shift) % len(inputs)
	out += inputs[key]

print out
s.sendall(out+"\n")

print s.recv(2048)
print s.recv(2048)

# Box 2

test = "ABAAAAA"
s.sendall(test+"\n")
rec = s.recv(2048)

print rec
resp = rec[rec.index("Expected"):]

ans = resp[resp.index("[")+1:-2]

print repr(ans)

out = ""
shift = 0
for l in ans:
	key = inputs.index(l)-shift
	shift += inputs.index(l) 
	shift = shift % len(inputs)
	out += inputs[key]

print out
s.sendall(out+"\n")
print s.recv(2048)
print s.recv(2048)

test = "ABCDA"
s.sendall(test+"\n")

rec = s.recv(2048)
print rec


out = ""
resp = rec[rec.index("[")+1:rec.index("\t")-1]
shift = inputs.index(resp[0])
shift -= inputs.index(test[0])
print shift, resp[0], test[0]

resp = rec[rec.index("Expected"):]

ans = resp[resp.index("[")+1:-2]

print repr(ans)
for l in ans:
	key = (inputs.index(l)-shift) % len(inputs)
	out += inputs[key]

print out 
out = out[::-1]

s.sendall(out+"\n")
print s.recv(2048)
print s.recv(2048)

s.sendall("A"*40+"\n")
rec = s.recv(2048)
key = rec[rec.index("[")+1:rec.index("\t")-1]

resp = rec[rec.index("Expected"):]

ans = resp[resp.index("[")+1:-2]

out = ""
for i in xrange(len(ans)):
	shift = inputs.index(key[i])
	out += inputs[(inputs.index(ans[i]) - shift)%len(inputs)]

print out

s.sendall(out + "\n")
print s.recv(2048)
print s.recv(2048)

#box 5

s.sendall("AAAA\n")
rec = s.recv(2048)

key = rec[rec.index("[")+1:rec.index("\t")-1]
resp = rec[rec.index("Expected"):]

ans = resp[resp.index("[")+1:-2]

shift = inputs.index(key[0])

out = ""
print ans
for l in ans:
	key = (inputs.index(l)-shift) % len(inputs)
	shift += inputs.index(l) % len(inputs)
	out += inputs[key]

s.sendall(out[::-1]+"\n")
print s.recv(2048)
print s.recv(2048)

s.sendall("A"*50+"\n")
rec = s.recv(2048)

key = rec[rec.index("[")+1:rec.index("\t")-1]
resp = rec[rec.index("Expected"):]

ans = resp[resp.index("[")+1:-2]
#ans = "".join([chr(0x41+(i%26)) for i in xrange(50)])

off = inputs.index(key[i])
print inputs
print key

out = ""
shift = 0
for j in xrange(0,len(ans),4):
	try:
		i = j
		out += inputs[(inputs.index(ans[i])-inputs.index(key[0])-shift)%len(inputs)]
		shift += inputs.index(ans[i])+1
		i = j+1
		out += inputs[(inputs.index(ans[i])-inputs.index(key[0])-shift)%len(inputs)]
		shift += inputs.index(ans[i])+1
		i = j+3
		out += inputs[(inputs.index(ans[i])-inputs.index(key[0])-shift)%len(inputs)]
		shift += inputs.index(ans[i])+1
		i = j+2
		out += inputs[(inputs.index(ans[i])-inputs.index(key[0])-shift)%len(inputs)]
		shift += inputs.index(ans[i])+1
	except:
		pass

print ans
print out
s.sendall(out+"\n")

rec = s.recv(2048)

key = rec[rec.index("[")+1:rec.index("\t")-1]
resp = rec[rec.index("Expected"):]
print rec

print s.recv(2048)
print s.recv(2048)
print s.recv(2048)
print s.recv(2048)

The flag is: Gr3aT j0b! BlackBox Ma$Ter$@!!!%%