[2020西湖论剑]Misc-Yusapapa-Writeup

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import os,random

from PIL import Image,ImageDraw

p=Image.open('flag.png').convert('L')

flag = []

a,b = p.size

for x in range(a):

for y in range(b):

if p.getpixel((x,y)) == 255:

flag.append(0)

else:

flag.append(1)
key1stream = []

for _ in range(len(flag)):

key1stream.append(random.randint(0,1))

random.seed(os.urandom(8))

key2stream = []

for _ in range(len(flag)):

key2stream.append(random.randint(0,1))

enc = []

for i in range(len(flag)):

enc.append(flag[i]^key1stream[i]^key2stream[i])
hide=Image.open('source.png').convert('RGB')

R=[]

G=[]

B=[]

a,b = hide.size

for x in range(a):

for y in range(b):

R.append(bin(hide.getpixel((x,y))[0]).replace('0b','').zfill(8))

G.append(bin(hide.getpixel((x, y))[1]).replace('0b','').zfill(8))

B.append(bin(hide.getpixel((x, y))[2]).replace('0b','').zfill(8))

R1=[]

G1=[]

B1=[]

for i in range(len(key1stream)):

if key1stream[i] == 1:

R1.append(R[i][:7]+'1')

else:

R1.append(R[i][:7]+'0')
for i in range(len(key2stream)):

if key2stream[i] == 1:

G1.append(G[i][:7]+'1')

else:

G1.append(G[i][:7]+'0')
for i in range(len(enc)):

if enc[i] == 1:

B1.append(B[i][:7]+'1')

else:

B1.append(B[i][:7]+'0')
for r in range(len(R)):

R[r] = int(R1[r],2)
for g in range(len(G)):

G[g] = int(G1[g],2)
for b in range(len(B)):

B[b] = int(B1[b],2)
a,b = hide.size

en_p = Image.new('RGB',(a,b),(255,255,255))

for x in range(a):

for y in range(b):

en_p.putpixel((x,y),(R[y+xb],G[y+xb],B[y+x*b]))
en_p.save('encode.png')

from PIL import Image,ImageDraw

p = Image.open('encode.png').convert('RGB')

a,b = p.size

R=[]

G=[]

B=[]

for x in range(a):

for y in range(b):

R.append(bin(p.getpixel((x,y))[0]).replace('0b','').zfill(8))

G.append(bin(p.getpixel((x, y))[1]).replace('0b', '').zfill(8))

B.append(bin(p.getpixel((x, y))[2]).replace('0b', '').zfill(8))

R1=[]

G1=[]

B1=[]

flag=[]

for i in range(len(R)):

R1.append(int(R[i][-1:]))

G1.append(int(G[i][-1:]))

B1.append(int(B[i][-1:]))

print(R1[100:150])

print(G1[100:150])

print(B1[100:150])

for i in range(len(R1)):

flag.append(B1[i]^G1[i]^R1[i])

print(flag[100:150])

de_p = Image.new('L',(a,b),255)

c=0
for x in range(a):

for y in range(b):

if flag[c] == 1:

de_p.putpixel((x,y),0)

else:

de_p.putpixel((x, y), 255)

c=c+1
de_p.save('out.png')