Ordine nelle cartelle. Modificato encrypt+decrypt

This commit is contained in:
Giulio De Pasquale 2017-05-29 16:08:56 +02:00
parent 1202a2156f
commit d6964e25c4
9 changed files with 565 additions and 0 deletions

128
polictf/asms/decrypt.pstc Normal file
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def datastrlen:
###############
# r0 = offset of str in data
# retval (r0) = strlen
###############
push r1
push r2
push r3
movr s2, r0
movi s1, 0
lodr s0, s2
cmpb s0, 0
jpei exit
loop:
movi s2, 0
addi s1, 1
addr s2, s1
lodr s0, s2
cmpb s0, 0
jpni loop
exit:
movr r0, s1
poop r3
poop r2
poop r1
retn
def round: # round(uint16_t text[2])
#################
# r0 = offset of text[0] in data
# r1 = offset of text[1] in data
# r2 = text[0]
# r3 = text[1]
# retval = void
################
push r1
push r2
push r3
lodr r2, r0 # text[0]
lodr r3, r1 # text[1]
movi s0, 0 # i
movi s1, 0 # sum
loop:
push s0 # saving i
addi s1, 0x626f # sum += delta
push s1 # saving sum
# s0 and s1 will be used as tmps
#########
# calc v0
#########
movr s0, r3
shli s0, 4
addi s0, 0x7065 # s0 = (text[1] << 4) + k0
movr s1, r3
poop s3 # restoring sum in s3
addr s1, s3 # s1 = text[1] + sum
push s3 # saving sum again
xorr s0, s1 # s0 = ((text[1] << 4) + k0) ^ (text[1] + sum)
push s0
movr s0, r3
shri s0, 5
addi s0, 0x7065 # s0 = (text[1] >> 5) + k1
poop s1
xorr s0, s1 # s0 = ((text[1] << 4) + k0) ^ (text[1] + sum) ^ ((text[1] >> 5) + k1)
addr r2, s0 # r2 += s0
#########
# calc v1
#########
movr s0, r2
shli s0, 4
addi s0, 0x7275 # s0 = (text[0] << 4) + k2
movr s1, r2
poop s3 # restoring sum in s3
addr s1, s3 # s1 = text[0] + sum
push s3 # saving sum again
xorr s0, s1 # s0 = ((text[0] << 4) + k2) ^ (text[0] + sum)
push s0
movr s0, r2
shri s0, 5
addi s0, 0x6e73 # s0 = (text[0] >> 5) + k3
poop s1
xorr s0, s1 # s0 = ((text[0] << 4) + k2) ^ (text[0] + sum) ^ ((text[0] >> 5) + k3)
addr r3, s0 # r3 += s0
######
# end loop
#####
poop s1 # restoring sum
poop s0 # restoring i
addi s0, 1
cmpb s0, 127 # while (i < 128)
jpbi loop
# saving the values
strr r0, r2
strr r1, r3
poop r3
poop r2
poop r1
retn
def main:
movi r0, 0xadde
movi r1, 0x0bb0
stri 0, r0
stri 2, r1
movi r0, 0x0bb0
movi r1, 0xcefa
stri 0x4, r0
stri 0x6, r1
movi r0, 0
call datastrlen
movr r2, r0
movi s0, 0
encrypt:
push s0
movi r0, 0
movi r1, 2
addr r0, s0
addr r1, s0
call round
poop s0
addi s0, 1
cmpr s0, r2
jpbi encrypt
lodi r0, 0
lodi r1, 2
lodi r2, 4
lodi r3, 6
shit

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polictf/asms/encrypt.pstc Normal file
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def datastrlen:
###############
# r0 = offset of str in data
# retval (r0) = strlen
###############
push r1
push r2
push r3
movr s2, r0
movi s1, 0
lodr s0, s2
cmpb s0, 0
jpei exit
loop:
movi s2, 0
addi s1, 1
addr s2, s1
lodr s0, s2
cmpb s0, 0
jpni loop
exit:
movr r0, s1
poop r3
poop r2
poop r1
retn
def round: # round(uint16_t text[2])
#################
# r0 = offset of text[0] in data
# r1 = offset of text[1] in data
# r2 = text[0]
# r3 = text[1]
# retval = void
################
push r1
push r2
push r3
lodr r2, r0 # text[0]
lodr r3, r1 # text[1]
movi s0, 0 # i
movi s1, 0 # sum
loop:
push s0 # saving i
addi s1, 0x626f # sum += delta
push s1 # saving sum
# s0 and s1 will be used as tmps
#########
# calc v0
#########
movr s0, r3
shli s0, 4
addi s0, 0x7065 # s0 = (text[1] << 4) + k0
movr s1, r3
poop s3 # restoring sum in s3
addr s1, s3 # s1 = text[1] + sum
push s3 # saving sum again
xorr s0, s1 # s0 = ((text[1] << 4) + k0) ^ (text[1] + sum)
push s0
movr s0, r3
shri s0, 5
addi s0, 0x7065 # s0 = (text[1] >> 5) + k1
poop s1
xorr s0, s1 # s0 = ((text[1] << 4) + k0) ^ (text[1] + sum) ^ ((text[1] >> 5) + k1)
addr r2, s0 # r2 += s0
#########
# calc v1
#########
movr s0, r2
shli s0, 4
addi s0, 0x7275 # s0 = (text[0] << 4) + k2
movr s1, r2
poop s3 # restoring sum in s3
addr s1, s3 # s1 = text[0] + sum
push s3 # saving sum again
xorr s0, s1 # s0 = ((text[0] << 4) + k2) ^ (text[0] + sum)
push s0
movr s0, r2
shri s0, 5
addi s0, 0x6e73 # s0 = (text[0] >> 5) + k3
poop s1
xorr s0, s1 # s0 = ((text[0] << 4) + k2) ^ (text[0] + sum) ^ ((text[0] >> 5) + k3)
addr r3, s0 # r3 += s0
######
# end loop
#####
poop s1 # restoring sum
poop s0 # restoring i
addi s0, 1
cmpb s0, 127 # while (i < 128)
jpbi loop
# saving the values
strr r0, r2
strr r1, r3
poop r3
poop r2
poop r1
retn
def main:
movi r0, 0xadde
movi r1, 0x0bb0
stri 0, r0
stri 2, r1
movi r0, 0x0bb0
movi r1, 0xcefa
stri 0x4, r0
stri 0x6, r1
movi r0, 0
call datastrlen
movr r2, r0
movi s0, 0
encrypt:
push s0
movi r0, 0
movi r1, 2
addr r0, s0
addr r1, s0
call round
poop s0
addi s0, 1
cmpr s0, r2
jpbi encrypt
lodi r0, 0
lodi r1, 2
lodi r2, 4
lodi r3, 6
shit

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#include "../../vm/vm.h"
#include <fstream>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[]) {
unsigned char banner[] = {
0x5f, 0x5f, 0x5f, 0x5f, 0x5f, 0x5f, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x5f, 0x20, 0x20, 0x20, 0x5f, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x5f, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x5f, 0x20, 0x20, 0x20, 0x5f, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x5f, 0x5f, 0x20, 0x20, 0x20, 0x5f, 0x5f, 0x5f, 0x5f, 0x5f, 0x20, 0x20,
0x5f, 0x5f, 0x5f, 0x5f, 0x5f, 0x20, 0x20, 0x5f, 0x5f, 0x5f, 0x5f, 0x5f,
0x5f, 0x0a, 0x7c, 0x20, 0x5f, 0x5f, 0x5f, 0x20, 0x5c, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x7c, 0x20, 0x7c, 0x20, 0x28, 0x5f, 0x29, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x28, 0x5f, 0x29, 0x20, 0x20,
0x20, 0x20, 0x20, 0x7c, 0x20, 0x7c, 0x20, 0x7c, 0x20, 0x7c, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x2f, 0x20, 0x20, 0x7c, 0x20, 0x7c, 0x5f, 0x5f, 0x5f, 0x5f, 0x20,
0x7c, 0x7c, 0x5f, 0x5f, 0x5f, 0x5f, 0x20, 0x7c, 0x7c, 0x5f, 0x5f, 0x5f,
0x20, 0x20, 0x2f, 0x0a, 0x7c, 0x20, 0x7c, 0x5f, 0x2f, 0x20, 0x2f, 0x5f,
0x20, 0x5f, 0x20, 0x5f, 0x5f, 0x5f, 0x7c, 0x20, 0x7c, 0x5f, 0x20, 0x5f,
0x20, 0x20, 0x5f, 0x5f, 0x5f, 0x20, 0x5f, 0x5f, 0x5f, 0x20, 0x5f, 0x20,
0x20, 0x5f, 0x5f, 0x5f, 0x20, 0x7c, 0x20, 0x7c, 0x5f, 0x7c, 0x20, 0x7c,
0x5f, 0x20, 0x5f, 0x5f, 0x5f, 0x20, 0x20, 0x20, 0x5f, 0x5f, 0x20, 0x20,
0x20, 0x5f, 0x5f, 0x60, 0x7c, 0x20, 0x7c, 0x20, 0x20, 0x20, 0x20, 0x20,
0x2f, 0x20, 0x2f, 0x20, 0x20, 0x20, 0x20, 0x2f, 0x20, 0x2f, 0x20, 0x20,
0x20, 0x2f, 0x20, 0x2f, 0x20, 0x0a, 0x7c, 0x20, 0x20, 0x5f, 0x5f, 0x2f,
0x20, 0x5f, 0x60, 0x20, 0x2f, 0x20, 0x5f, 0x5f, 0x7c, 0x20, 0x5f, 0x5f,
0x7c, 0x20, 0x7c, 0x2f, 0x20, 0x5f, 0x5f, 0x2f, 0x20, 0x5f, 0x5f, 0x7c,
0x20, 0x7c, 0x2f, 0x20, 0x5f, 0x20, 0x5c, 0x7c, 0x20, 0x5f, 0x5f, 0x7c,
0x20, 0x5f, 0x5f, 0x2f, 0x20, 0x5f, 0x20, 0x5c, 0x20, 0x20, 0x5c, 0x20,
0x5c, 0x20, 0x2f, 0x20, 0x2f, 0x20, 0x7c, 0x20, 0x7c, 0x20, 0x20, 0x20,
0x20, 0x20, 0x5c, 0x20, 0x5c, 0x20, 0x20, 0x20, 0x20, 0x5c, 0x20, 0x5c,
0x20, 0x20, 0x2f, 0x20, 0x2f, 0x20, 0x20, 0x0a, 0x7c, 0x20, 0x7c, 0x20,
0x7c, 0x20, 0x28, 0x5f, 0x7c, 0x20, 0x5c, 0x5f, 0x5f, 0x20, 0x5c, 0x20,
0x7c, 0x5f, 0x7c, 0x20, 0x7c, 0x20, 0x28, 0x5f, 0x7c, 0x20, 0x28, 0x5f,
0x5f, 0x7c, 0x20, 0x7c, 0x20, 0x28, 0x5f, 0x29, 0x20, 0x7c, 0x20, 0x7c,
0x5f, 0x7c, 0x20, 0x7c, 0x7c, 0x20, 0x28, 0x5f, 0x29, 0x20, 0x7c, 0x20,
0x20, 0x5c, 0x20, 0x56, 0x20, 0x2f, 0x20, 0x5f, 0x7c, 0x20, 0x7c, 0x5f,
0x2e, 0x5f, 0x5f, 0x5f, 0x2f, 0x20, 0x2f, 0x2e, 0x5f, 0x5f, 0x5f, 0x2f,
0x20, 0x2f, 0x2e, 0x2f, 0x20, 0x2f, 0x20, 0x20, 0x20, 0x0a, 0x5c, 0x5f,
0x7c, 0x20, 0x20, 0x5c, 0x5f, 0x5f, 0x2c, 0x5f, 0x7c, 0x5f, 0x5f, 0x5f,
0x2f, 0x5c, 0x5f, 0x5f, 0x7c, 0x5f, 0x7c, 0x5c, 0x5f, 0x5f, 0x5f, 0x5c,
0x5f, 0x5f, 0x5f, 0x7c, 0x5f, 0x7c, 0x5c, 0x5f, 0x5f, 0x5f, 0x2f, 0x20,
0x5c, 0x5f, 0x5f, 0x7c, 0x5c, 0x5f, 0x5f, 0x5c, 0x5f, 0x5f, 0x5f, 0x2f,
0x20, 0x20, 0x20, 0x20, 0x5c, 0x5f, 0x28, 0x5f, 0x29, 0x5c, 0x5f, 0x5f,
0x5f, 0x2f, 0x5c, 0x5f, 0x5f, 0x5f, 0x5f, 0x28, 0x5f, 0x29, 0x5f, 0x5f,
0x5f, 0x5f, 0x2f, 0x20, 0x5c, 0x5f, 0x2f, 0x20, 0x20, 0x20, 0x20, 0x0a,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x0a, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x0a, 0x20, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f,
0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f,
0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f,
0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f,
0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f,
0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f,
0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f,
0x5c, 0x2f, 0x7c, 0x20, 0x20, 0x0a, 0x7c, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c,
0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c,
0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c,
0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c,
0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c,
0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c,
0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c, 0x2f, 0x2f, 0x5c,
0x2f, 0x2f, 0x5c, 0x2f, 0x20, 0x20, 0x20};
unsigned char bc[] = {
0x48, 0x00, 0xde, 0xad, 0x48, 0x01, 0xb0, 0x0b, 0xd4, 0x00, 0x00, 0x00,
0xd4, 0x02, 0x00, 0x01, 0x48, 0x00, 0xb0, 0x0b, 0x48, 0x01, 0xfa, 0xce,
0xd4, 0x04, 0x00, 0x00, 0xd4, 0x06, 0x00, 0x01, 0x48, 0x00, 0x00, 0x00,
0xd8, 0xd9, 0x00, 0xcb, 0x20, 0x48, 0x04, 0x00, 0x00, 0xde, 0x04, 0x48,
0x00, 0x00, 0x00, 0x48, 0x01, 0x02, 0x00, 0x39, 0x04, 0x39, 0x14, 0xd8,
0x5a, 0x00, 0x5c, 0x04, 0x05, 0x04, 0x01, 0x00, 0xd7, 0x42, 0x93, 0x2d,
0x00, 0x22, 0x00, 0x00, 0x00, 0x22, 0x01, 0x02, 0x00, 0x22, 0x02, 0x04,
0x00, 0x22, 0x03, 0x06, 0x00, 0x5d, 0xde, 0x01, 0xde, 0x02, 0xde, 0x03,
0x12, 0x20, 0x12, 0x31, 0x48, 0x04, 0x00, 0x00, 0x48, 0x05, 0x00, 0x00,
0xde, 0x04, 0x05, 0x05, 0x6f, 0x62, 0xde, 0x05, 0xcb, 0x43, 0x20, 0x04,
0x04, 0x00, 0x05, 0x04, 0x65, 0x70, 0xcb, 0x53, 0x5c, 0x07, 0x39, 0x57,
0xde, 0x07, 0xb1, 0x45, 0xde, 0x04, 0xcb, 0x43, 0x36, 0x04, 0x05, 0x00,
0x05, 0x04, 0x65, 0x70, 0x5c, 0x05, 0xb1, 0x45, 0x39, 0x24, 0xcb, 0x42,
0x20, 0x04, 0x04, 0x00, 0x05, 0x04, 0x75, 0x72, 0xcb, 0x52, 0x5c, 0x07,
0x39, 0x57, 0xde, 0x07, 0xb1, 0x45, 0xde, 0x04, 0xcb, 0x42, 0x36, 0x04,
0x05, 0x00, 0x05, 0x04, 0x73, 0x6e, 0x5c, 0x05, 0xb1, 0x45, 0x39, 0x34,
0x5c, 0x05, 0x5c, 0x04, 0x05, 0x04, 0x01, 0x00, 0xf4, 0x04, 0x7f, 0x93,
0x6c, 0x00, 0x4e, 0x02, 0x4e, 0x13, 0x5c, 0x03, 0x5c, 0x02, 0x5c, 0x01,
0xbb, 0xde, 0x01, 0xde, 0x02, 0xde, 0x03, 0xcb, 0x60, 0x48, 0x05, 0x00,
0x00, 0x12, 0x46, 0xf4, 0x04, 0x00, 0x38, 0xff, 0x00, 0x48, 0x06, 0x00,
0x00, 0x05, 0x05, 0x01, 0x00, 0x39, 0x65, 0x12, 0x46, 0xf4, 0x04, 0x00,
0xae, 0xed, 0x00, 0xcb, 0x05, 0x5c, 0x03, 0x5c, 0x02, 0x5c, 0x01, 0xbb};
unsigned int bclen = 264;
unsigned char opcode_key[] = {0x48, 0x61, 0x76, 0x65, 0x46, 0x75, 0x6e,
0x21, 0x50, 0x6f, 0x6c, 0x69, 0x43, 0x54,
0x46, 0x32, 0x30, 0x31, 0x37, 0x21};
printf("%s", banner);
printf("\nHmmm...\n");
VM vm(opcode_key, bc, bclen);
vm.run();
return 0;
}

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#include "../../vm/vm.h"
#include "../../vm/debug.h"
#include <fstream>
#include <iostream>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#define KEYLEN 15
#define CODESIZE 0x300
#define DATAKEYLEN 30
void gen_random(uint8_t *s, const int len) {
srand(time(NULL));
static const char alphanum[] = "0123456789"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz";
for (int i = 0; i < len; ++i) {
s[i] = alphanum[rand() % (sizeof(alphanum) - 1)];
}
s[len] = 0;
}
unsigned char encrypted_data[] = {
0xcc, 0x8d, 0x5a, 0xcc, 0x73, 0xb5, 0xf2, 0xa3, 0xf3, 0x92,
0xa8, 0x8f, 0x2f, 0xf1, 0x3e, 0xf4, 0x69, 0x00, 0x4a, 0xcb,
0xed, 0xc4, 0x57, 0x9b, 0xf6, 0x9a, 0x78, 0x46, 0x83, 0xe9};
unsigned int encrypted_data_len = 30;
int main(int argc, char *argv[]) {
uint8_t *key = new uint8_t[KEYLEN], *decdatasec = new uint8_t[DATAKEYLEN],
*flag = new uint8_t[DATAKEYLEN];
uint8_t *clientcode;
uint8_t i;
uint32_t clientcodesize, bytesread;
FILE *datap, *flagp;
gen_random(key, KEYLEN);
printf("Use this: \"%s\"\n", key);
fflush(stdout);
printf("How much data are you sending me?\n");
fflush(stdout);
scanf("%d", &clientcodesize);
printf("Go ahead then!\n");
fflush(stdout);
clientcode = new uint8_t[clientcodesize];
bytesread = read(0, clientcode, clientcodesize);
if (bytesread != clientcodesize) {
printf("ERROR! Couldn't read everything!\n");
fflush(stdout);
exit(1);
}
VM vm(key, clientcode, clientcodesize);
vm.as.insData(encrypted_data, encrypted_data_len);
vm.run();
datap = fopen("../res/decrypteddatasection.txt", "r");
if (datap == NULL) {
printf("Couldn't open decrypteddatasection.txt!\n");
fflush(stdout);
exit(1);
}
fscanf(datap, "%s", decdatasec);
fclose(datap);
for (i = 0; i < DATAKEYLEN; i++) {
if (vm.as.data[i] != decdatasec[i]) {
DBG_INFO(("Checking data[%d]..\n", i));
fflush(stdout);
printf("Nope!\n");
fflush(stdout);
exit(1);
}
}
flagp = fopen("../res/flag.txt", "r");
if (flagp == NULL) {
printf("Couldn't open flag.txt!\n");
fflush(stdout);
exit(1);
}
fscanf(flagp, "%s", flag);
fclose(flagp);
printf("Congratulations!\nThe flag is: %s\n", flag);
fflush(stdout);
return 0;
}

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4 test

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¯“©žÚÈÓÛgJ W‰\µž1bímŒ«Úre

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#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
void decrypt(uint16_t *v) {
uint16_t v0 = v[0], v1 = v[1], sum = 0x3780, i; /* set up */
uint16_t delta = 0x626f; /* a key schedule constant */
uint16_t k0 = 0x7065; // "pe"
uint16_t k1 = 0x7065; // "pe"
uint16_t k2 = 0x7275; // "ru"
uint16_t k3 = 0x6e73; // "ns"
for (i = 0; i < 128; i++) {
// printf("Intermediate v0: 0x%x | v1: 0x%x\n", v0, v1); /* basic cycle
// start */
v1 -= ((v0 << 4) + k2) ^ (v0) ^ ((v0 >> 5) + k3);
v0 -= ((v1 << 4) + k0) ^ (v1) ^ ((v1 >> 5) + k1);
sum -= delta;
} /* end cycle */
v[0] = v0;
v[1] = v1;
}
int main(int argc, char *argv[]) {
uint8_t buf[1000];
uint32_t buflen, i;
fprintf(stdout, "Length of the string?\n");
fflush(stdout);
fscanf(stdin, "%d", &buflen);
printf("Length: %d\n", buflen);
read(0, buf, buflen);
for (i = 0; i < buflen && i + 2 * (sizeof(uint16_t)) <= buflen;
i += sizeof(uint32_t)) {
decrypt((uint16_t *)&buf[i]);
}
for (i = 0; i < buflen; i++) {
fprintf(stdout, "buf[%d] = 0x%02x\n", i, buf[i]);
}
printf("STRING: %s\n", buf);
fflush(stdout);
}

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#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
void encrypt(uint16_t *v) {
uint16_t v0 = v[0], v1 = v[1], sum = 0, i; /* set up */
uint16_t delta = 0x626f;
uint16_t k0 = 0x7065; // "pe"
uint16_t k1 = 0x7065; // "pe"
uint16_t k2 = 0x7275; // "ru"
uint16_t k3 = 0x6e73; // "ns"
// printf("v0: 0x%x, v1: 0x%x\n", v0, v1);
for (i = 0; i < 128; i++) {
sum += delta;
v0 += ((v1 << 4) + k0) ^ (v1) ^ ((v1 >> 5) + k1);
v1 += ((v0 << 4) + k2) ^ (v0) ^ ((v0 >> 5) + k3);
// printf("Intermediate v0: 0x%x | v1: 0x%x\n", v0, v1);
}
// printf("SUM: 0x%x\n", sum);
// printf("v0: 0x%x, v1: 0x%x\n", v0, v1);
v[0] = v0;
v[1] = v1;
}
int main(int argc, char *argv[]) {
uint8_t *buf;
uint32_t buflen, i;
FILE *f;
if (argc != 2) {
printf("Usage: %s text_to_encrypt", argv[0]);
exit(1);
}
buflen = strlen(argv[1]);
buf = (uint8_t *)malloc(buflen);
memcpy(buf, argv[1], buflen);
for (i = 0; i < buflen && i + 2 * (sizeof(uint16_t)) <= buflen;
i += sizeof(uint32_t)) {
encrypt((uint16_t *)&buf[i]);
}
write(1, buf, buflen);
return 0;
}

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from pwn import *
r = remote("127.0.0.1", 8888)
with open("./encrypted") as f:
data = f.read()
print(r.recv())
r.send("{}\n".format(len(data)))
r.send("{}\n".format(data))
print(r.recv())