def test_write_image_diff_size_pil():
"""Writing out an image creates a file of a different size, if the file was generated by PIL originally."""
clean_file = CLEAN_PNG_LOCATION
dirty_file = "tests/dirtyImage_test_write_image_file_diff_size_pil.png"
clean_file_pil = "tests/cleanImagePIL.png"
with Image.open(clean_file) as pil_image:
pil_image.save(clean_file_pil)
stegs = Steganographer()
clean_data = _open_image_file(clean_file_pil)
dirty_data = clean_data[0], stegs._hide_string(
clean_data[1], "Hidden text from test_write_image_diff_size_pil.")
output_file = _write_image_file(dirty_file, clean_file_pil, dirty_data)
# Getting the file sizes for the clean and dirty files.
with open(clean_file_pil, 'rb') as clean:
clean.seek(0, 2)
clean_file_size = clean.tell()
with open(output_file, 'rb') as dirty:
dirty.seek(0, 2)
dirty_file_size = dirty.tell()
assert clean_file_size != dirty_file_size
os.remove(output_file)
def test_hide_reveal_string_inverse(string_to_hide):
"""Anything hidden by _hide_string is revealed by _reveal_string."""
clean_data = bytes(b'\x01' * 5000)
stegs = Steganographer()
stegs._header.data_len = len(string_to_hide.encode('utf-8'))
revealed_string = stegs._reveal_string(
stegs._hide_string(clean_data, string_to_hide))
assert revealed_string == string_to_hide
def test_exact_data_with_string_inverse():
"""The string entered is the string returned. The storing data is the exact length needed."""
test_string = "This is a test String"
stegs = Steganographer()
stegs._header.data_len = len(test_string)
blank_data = bytes(b'\x01' * len(test_string) * stegs._BYTELEN)
revealed_string = stegs._reveal_string(
stegs._hide_string(blank_data, test_string))
assert test_string == revealed_string
def test_short_data_with_string_inverse():
"""When the data is too small, by a full byte, everything that can be returned is returned."""
test_string = "This is a test String"
stegs = Steganographer()
stegs._header.data_len = len(test_string)
blank_data = bytes(b'\x01' *
(len(test_string) * stegs._BYTELEN - stegs._BYTELEN))
revealed_string = stegs._reveal_string(
stegs._hide_string(blank_data, test_string))
assert test_string[:-1] == revealed_string
def test_hide_string():
"""Takes in a string and a bytes object and hides the string in that bytes object."""
stegs = Steganographer()
test_data = bytes(b'\x01' * stegs._BYTELEN * 3)
solution_data = bytearray(stegs._BYTELEN * 3)
solution_data[1] = 1
solution_data[7] = 1
solution_data[9] = 1
solution_data[14] = 1
solution_data[17] = 1
solution_data[22] = 1
solution_data[23] = 1
assert stegs._hide_string(test_data, 'ABC') == solution_data
def test_write_image_same_image():
"""Writing out an image creates the same image when viewed generally."""
clean_file = CLEAN_PNG_LOCATION
dirty_file = "tests/dirtyImage_test_write_image_file_same_image.png"
stegs = Steganographer()
clean_data = _open_image_file(clean_file)
dirty_data = clean_data[0], stegs._hide_string(
clean_data[1], "Hidden text from test_write_image_same_image.")
output_file = _write_image_file(dirty_file, clean_file, dirty_data)
assert compare_images(clean_file, output_file) < 500
os.remove(output_file)
def test_write_bin_diff_content():
"""The file written is different from the one read, after hiding a message."""
clean_file = CLEAN_PNG_LOCATION
dirty_file = "tests/dirtyImage_test_write_bin_file_diff_content.png"
stegs = Steganographer()
data = stegs._hide_string(_open_bin_file(clean_file),
"Hidden text from test_write_bin_diff_content.")
_write_bin_file(dirty_file, data)
with open(clean_file, 'rb') as clean, open(dirty_file, 'rb') as dirty:
assert clean.read() != dirty.read()
os.remove(dirty_file)
def test_short_partial_data_string_inverse():
"""When the data is too small, by a half byte, everything that can be returned is returned."""
test_string = "This is a test String"
stegs = Steganographer()
stegs._header.data_len = len(test_string)
solution_string = test_string[:-1] + chr(
ord(test_string[-1]) >> stegs._BYTELEN // 2 << stegs._BYTELEN // 2)
blank_data = bytes(
b'\x01' * (len(test_string) * stegs._BYTELEN - stegs._BYTELEN // 2))
revealed_string = stegs._reveal_string(
stegs._hide_string(blank_data, test_string))
assert solution_string == revealed_string
def test_write_image_diff_content():
"""Writing out an image creates a different image at the bit level."""
clean_file = CLEAN_PNG_LOCATION
dirty_file = "tests/dirtyImage_test_write_image_file_diff_content.png"
stegs = Steganographer()
clean_data = _open_image_file(clean_file)
dirty_data = clean_data[0], stegs._hide_string(
clean_data[1], "Hidden text from test_write_image_diff_content.")
output_file = _write_image_file(dirty_file, clean_file, dirty_data)
with open(clean_file, 'rb') as clean, open(output_file, 'rb') as dirty:
assert clean.read() != dirty.read()
os.remove(output_file)
def test_write_image_file_valid():
"""The image created is not corrupt."""
clean_file = CLEAN_PNG_LOCATION
dirty_file = "tests/dirtyImage_test_write_image_file_valid_image.png"
stegs = Steganographer()
clean_data = _open_image_file(clean_file)
dirty_data = clean_data[0], stegs._hide_string(
clean_data[1], "Hidden text from test_write_image_file_valid.")
output_file = _write_image_file(dirty_file, clean_file, dirty_data)
try:
Image.open(output_file)
except OSError:
pytest.fail("Image is corrupt " + output_file)
os.remove(output_file)
def test_write_bin_file_size_same():
"""The file written is the same size as the one read, after hiding a message."""
clean_file = CLEAN_PNG_LOCATION
dirty_file = "tests/dirtyImage_test_write_bin_file_size_same.png"
stegs = Steganographer()
data = stegs._hide_string(
_open_bin_file(clean_file),
"Hidden text from test_write_bin_file_size_same.")
_write_bin_file(dirty_file, data)
# Getting the file sizes for the clean and dirty files.
with open(clean_file, 'rb') as clean:
clean.seek(0, 2)
clean_file_size = clean.tell()
with open(dirty_file, 'rb') as dirty:
dirty.seek(0, 2)
dirty_file_size = dirty.tell()
assert clean_file_size == dirty_file_size
os.remove(dirty_file)
