def test_get_bit_pairs(self):
# T -> 0b1010100
# e -> 0b1100101
# s -> 0b1110011
# t -> 0b1110100
# -> 0b100000
# t -> 0b1110100
# e -> 0b1100101
# x -> 0b1111000
# t -> 0b1110100
text = 'Test text'
expected_output = (
'01', '01', '01', '00',
'01', '10', '01', '01',
'01', '11', '00', '11',
'01', '11', '01', '00',
'00', '10', '00', '00',
'01', '11', '01', '00',
'01', '10', '01', '01',
'01', '11', '10', '00',
'01', '11', '01', '00',
)
sample_img = np.zeros((5, 5, 3), np.uint8)
obj = Encrypter(sample_img, text)
pairs = obj.get_bit_pairs(text)
self.assertEqual(pairs, expected_output)
def test_set_bit_no_actual_change(self):
initial = "10010100" # 148 in binary
output = Encrypter.set_bit(int(initial, 2), 6, 0)
self.assertEqual(bin(output)[2:], initial)
initial = "10010100" # 148 in binary
output = Encrypter.set_bit(int(initial, 2), 2, 1)
self.assertEqual(bin(output)[2:], initial)
def test_code_pixel(self):
sample_img = np.zeros((5, 5, 3), np.uint8)
text = 'Test text'
obj = Encrypter(sample_img, text)
self.assertEqual(sample_img.item(0, 0, 0), 0)
obj.code_pixel(0, 0, 0, '11') # '0b11' = 3 in decimal
first_px = sample_img.item(0, 0, 0)
self.assertEqual(first_px, 3)
def test_decode_message(self):
msg = 'Test message'
img = np.zeros((10, 10, 3), np.uint8)
encrypter = Encrypter(img, msg)
encrypter.encode()
decrypter = Decrypter(encrypter.img)
result = decrypter.decode_message()
self.assertEqual(result, msg)
def test_encode(self):
# Just one character because encoding requires 32 bits for
# input end message
text = 'x' # 01111000 - (1, 3, 2, 0) (bit pairs decimal repr)
img = np.zeros((6, 6, 1), np.uint8)
obj = Encrypter(img, text)
obj.encode()
self.assertEqual(img.item(0, 0, 0), 1)
self.assertEqual(img[0][1], 3)
self.assertEqual(img[0][2], 2)
self.assertEqual(img[0][3], 0)
def test_convert_to_bytes_string(self):
char = 'a' # 7 bits
py_bin = bin(ord(char))
self.assertEqual(len(py_bin[2:]), 7)
my_bin = Encrypter.convert_to_bytes_string(char)
self.assertEqual(len(my_bin), 8)
self.assertEqual(py_bin[2:], my_bin[1:])
def test_end_message_found(self):
sample_img = np.zeros((5, 5, 3), np.uint8)
decrypter = Decrypter(sample_img)
msg = '0110001001010011' # just random
self.assertFalse(decrypter.end_message_found(msg))
msg = 'test' + Decrypter.ENDMSG_CODE
bin_msg = ''
for x in msg:
binary = Encrypter.convert_to_bytes_string(x)
bin_msg += binary
self.assertTrue(decrypter.end_message_found(bin_msg[-64:]))
def test_can_encrypt_method(self):
# 32 pixels are required for end message code
# 4 x 4 x 3 = 48; (48 - 32) / 4 = 4 -> 4 characters possible
img_small = np.zeros((4, 4, 3), np.uint8)
# 5 x 5 x 3 = 75; (75 - 32) / 4 ~= 10+ -> 10 characters possible
img_ok = np.zeros((5, 5, 3), np.uint8)
# 6x6 - minimum image size for encryption
img_one_channel = np.zeros((6, 6, 1), np.uint8)
text_small = "test"
text = "10letters!"
text_long = "Too long string"
self.assertTrue(Encrypter.can_encrypt(img_small, text_small))
self.assertFalse(Encrypter.can_encrypt(img_small, text))
self.assertTrue(Encrypter.can_encrypt(img_ok, text))
self.assertFalse(Encrypter.can_encrypt(img_ok, text_long))
self.assertFalse(Encrypter.can_encrypt(img_one_channel, text))
self.assertTrue(Encrypter.can_encrypt(img_one_channel, "1"))
def test_set_bit_to_0(self):
initial = "10010100" # 148 in binary
index = 2
expected_value = "10010000"
output = Encrypter.set_bit(int(initial, 2), index, 0)
self.assertEqual(bin(output)[2:], expected_value)