def generate_keys(key_text):
key = []
for i in key_text:
key.extend(to_binary(ord(i)))
C = []
D = []
r = []
for i in range(28):
C.append(key[PC1_C[i]])
for i in range(28):
D.append(key[PC1_D[i]])
for i in range(0, 16):
if i in [0, 1, 8, 15]:
C = left_shift(C, 1)
D = left_shift(D, 1)
else:
C = left_shift(C, 2)
D = left_shift(D, 2)
CD = []
CD.extend(C)
CD.extend(D)
dummy = []
for i in range(48):
dummy.append(CD[PC2[i]])
r.append(dummy)
return r
def linear_s_box():
s_box = [[0 for col in range(16)] for row in range(4)]
bin = []
for i in range(64):
bin = to_binary(i)
s_box[bin[2] * 2 + b[7]][b[3] * 8 + b[4] * 4 + b[5] * 2 +
b[6]] = b[3] * 8 + b[4] * 4 + b[5] * 2 + b[6]
def decode(filename, keys):
fi = open(filename, "rb")
cipher = fi.read()
fi.close()
cipher_bits = []
header_str = ''
for i in cipher:
cipher_bits.extend(to_binary(ord(i)))
header_bits = cipher_bits[0:HEADER_LENGTH]
text_bits = cipher_bits[HEADER_LENGTH:]
for i in header_bits:
header_str += str(i)
text_bits = add_pads_if_necessary(text_bits)
keys.reverse()
bin_mess = ''
for i in range(0, len(text_bits), 64):
bin_mess += DES(text_bits, i, (i + 64), keys)
text_mess = header_str + bin_mess
i = 0
fo = open("decrypted_ecb.bmp", 'wb')
print("The length of final_cipher")
print(len(text_mess))
while i < len(text_mess) - 8:
val = bin_to_dec(text_mess[i:i + 4]) * 16 + bin_to_dec(text_mess[i + 4:i + 8])
fo.write(struct.pack('B', val))
i += 8
fo.close()
print('the original image has been saved in decrypted_ecb.bmp')
def generate_keys(key_text):
key = []
for i in key_text:
key.extend(to_binary(ord(i)))
C = []
D = []
r = []
for i in range(28):
C.append(key[PC1_C[i]])
for i in range(28):
D.append(key[PC1_D[i]])
for i in range(0, 16):
if i in [0, 1, 8, 15]:
C = left_shift(C, 1)
D = left_shift(D, 1)
else:
C = left_shift(C, 2)
D = left_shift(D, 2)
CD = []
CD.extend(C)
CD.extend(D)
dummy = []
for i in range(48):
dummy.append(CD[PC2[i]])
r.append(dummy)
return r
def decode(filename, keys):
fi = open(filename, "rb")
cipher = fi.read()
fi.close()
cipher_bits = []
header_str = ''
for i in cipher:
cipher_bits.extend(to_binary(ord(i)))
header_bits = cipher_bits[0:HEADER_LENGTH]
text_bits = cipher_bits[HEADER_LENGTH:]
for i in header_bits:
header_str += str(i)
text_bits = add_pads_if_necessary(text_bits)
keys.reverse()
bin_mess = ''
for i in range(0, len(text_bits), 64):
bin_mess += DES(text_bits, i, (i + 64), keys)
text_mess = header_str + bin_mess
i = 0
fo = open("decrypted_ecb.bmp", 'wb')
print("The length of final_cipher")
print(len(text_mess))
while i < len(text_mess) - 8:
val = bin_to_dec(text_mess[i:i + 4]) * 16 + bin_to_dec(
text_mess[i + 4:i + 8])
fo.write(struct.pack('B', val))
i += 8
fo.close()
print('the original image has been saved in decrypted_ecb.bmp')
def non_linear_s_box():
s_box = []
for i in range(64):
s_box.append(0)
for i in range(64):
b = to_binary(i)
s_box[(b[2] * 2 + b[7]) * 16 + b[3] * 8 + b[4] * 4 + b[5] * 2 + b[6]] = b[3] ** 4 + b[4] ** 3 + b[5] ** 2 + b[6]
return s_box
def non_linear_s_box():
s_box = []
for i in range(64):
s_box.append(0)
for i in range(64):
b = to_binary(i)
s_box[(b[2] * 2 + b[7]) * 16 + b[3] * 8 + b[4] * 4 + b[5] * 2 +
b[6]] = b[3]**4 + b[4]**3 + b[5]**2 + b[6]
return s_box
def split_header_and_content(img):
"""plain text to binary, split header and content for image
"""
cipher_bits = []
for i in img:
cipher_bits.extend(to_binary(ord(i)))
header_bits = cipher_bits[0:HEADER_LENGTH]
text_bits = cipher_bits[HEADER_LENGTH:]
return header_bits, text_bits
def split_header_and_content(img):
"""plain text to binary, split header and content for image
"""
cipher_bits = []
for i in img:
cipher_bits.extend(to_binary(ord(i)))
header_bits = cipher_bits[0: HEADER_LENGTH]
text_bits = cipher_bits[HEADER_LENGTH:]
return header_bits, text_bits
def s_box(block):
"""s-box function to reduce 48 bit block to 32 bit block
"""
for i in range(0, 8):
#获得行数
row = str(block[i][0]) + str(block[i][-1])
column = ''
for j in range(1, 5):
column += str(block[i][j])
a = 16 * get_row(row)
#获得列数
a += get_column(column)
block.pop(i)
block.insert(i, to_binary(ord(chr(s[i][a]))))
r = []
for i in block:
r.extend(i[4:8])
return r
def s_box(block):
"""s-box function to reduce 48 bit block to 32 bit block
"""
for i in range(0, 8):
#获得行数
row = str(block[i][0]) + str(block[i][-1])
column = ''
for j in range(1, 5):
column += str(block[i][j])
a = 16 * get_row(row)
#获得列数
a += get_column(column)
block.pop(i)
block.insert(i, to_binary(ord(chr(s[i][a]))))
r = []
for i in block:
r.extend(i[4:8])
return r
def linear_s_box():
s_box = [[0 for col in range(16)] for row in range(4)]
bin = []
for i in range(64):
bin = to_binary(i)
s_box[bin[2] * 2 + b[7]][b[3] * 8 + b[4] * 4 + b[5] * 2 + b[6]] = b[3] * 8 + b[4] * 4 + b[5] * 2 + b[6]