src.ch06 package

Submodules

src.ch06.c1_invisible_ink_mono module

Use stenography to hide messages in a word processor document.

Use docx.Document to hide encrypted messages in a word processor document by embedding the encrypted message in a fake message’s whitespace, then changing the encrypted message’s font color to white.

Note

Using LibreOffice version 6.0.7.3

Warning

There are many ways this method of stenography can fail. Please don’t use for actual covert operations (covered in MIT License).

src.ch06.c1_invisible_ink_mono.check_fit(plaintext: list, ciphertext: list) → int

Check if ciphertext can fit in plaintext’s whitespace.

Sum number of blanks in plaintext and compare to number of characters in ciphertext to see if it can fit.

Parameters

• plaintext (list) – Paragraphs of a fake message in a list of strings (likely from get_text()).

• ciphertext (list) – Paragraphs of an encrypted message in a list of strings (likely from get_text()).

Returns

Integer representing the number of needed blanks to fit ciphertext in plaintext. 0 would mean that ciphertext can fit in plaintext.

Note

To separate words, the blanks in ciphertext count toward the needed length of plaintext. By contrast, blank lines in plaintext do not count.

src.ch06.c1_invisible_ink_mono.main(fakefile: str = None, cipherfile: str = None, savepath: str = None) → None

Demonstrate the invisible ink writer.

Demonstrate write_invisible(), but for testing, it is a basic wrapper function for write_invisible(). Embed cipherfile in fakefile’s whitespace.

Parameters

• fakefile (str) – Path to .docx file with fake message. Defaults to ./c1files/fake.docx.

• cipherfile (str) – Path to .docx file with real message. Defaults to ./c1files/real.docx.

• savepath (str) – Path to .docx file for output. Defaults to ./c1files/DearInternet.docx.

Returns

None. The contents of cipherfile’s text is embedded in fakefile’s whitespace and saved to savepath.

src.ch06.c1_invisible_ink_mono.write_invisible(plaintext: list, ciphertext: list, template_path: str = None, filename: str = 'output.docx') → None

Embed ciphertext in plaintext’s letter whitespace.

Open a template file, template_path, with the needed fonts, styles, and margins. Write each line in plaintext to the template file and add each line in ciphertext to plaintext’s space between letters by using a monospace font. Save the new file as filename.

Parameters

• plaintext (list) – Lines of a fake message in a list of strings (likely from get_text()).

• ciphertext (list) – Lines of an encrypted message in a list of strings (likely from get_text()).

• template_path (str) – Absolute path to .docx file with predefined fonts, styles, and margins. Defaults to None. If not provided, defaults will be created.

• filename (str) – File name to use for output file. Defaults to output.docx.

Returns

None. plaintext is written to the file at template_path with ciphertext embedded in the blank space.

Raises

ValueError – If the number of spaces in plaintext aren’t enough to embed ciphertext based on output of check_fit().

Note

As of python-docx v0.8.10, creating custom styles isn’t well supported. More info here.

As a result, if a template isn’t provided, the default template is modified to use a font named Courier New on Windows and Liberation Mono on other operating systems in the Normal style.

src.ch06.p1_invisible_ink module

Use stenography to hide messages in a word processor document.

Use docx.Document to hide encrypted messages in a word processor document by embedding the encrypted message in a fake message’s whitespace, then changing the encrypted message’s font color to white.

Note

Using LibreOffice version 6.0.7.3

Warning

There are many ways this method of stenography can fail. Please don’t use for actual covert operations (covered in MIT License).

src.ch06.p1_invisible_ink.check_blanks(plaintext: list, ciphertext: list) → int

Check if the ciphertext can fit in plaintext.

Compare the number of blank lines in plaintext to the number of lines in ciphertext. If they aren’t a match, returns the number of extra blank lines needed.

Parameters

• plaintext (list) – Paragraphs of a fake message in a list of strings (likely from get_text()).

• ciphertext (list) – Paragraphs of an encrypted message in a list of strings (likely from get_text()).

Returns

Integer representing the number of needed blank lines to fit ciphertext in plaintext. 0 would mean that ciphertext can fit in plaintext.

src.ch06.p1_invisible_ink.get_text(file_path: str, skip_blank: bool = True) → list

Get text from a docx file.

Loads paragraphs from the given docx file into a list. Optionally skips blank lines.

Parameters

• file_path (str) – Absolute path to a .docx file to load.

• skip_blank (bool) – Whether or not to skip blank lines. Defaults to True.

Returns

Each paragraph in the docx file in a list of strings.

Note

Does not copy formatting from docx file - only text.

src.ch06.p1_invisible_ink.main(fakefile: str = None, cipherfile: str = None, savepath: str = None) → None

Demonstrate the invisible ink writer.

Demonstrate write_invisible(), but for testing, it is a basic wrapper function for write_invisible(). Embed cipherfile in fakefile’s whitespace.

Parameters

• fakefile (str) – Path to .docx file with fake message. Defaults to ./p1files/fake.docx.

• cipherfile (str) – Path to .docx file with real message. Defaults to ./p1files/real.docx.

• savepath (str) – Path to .docx file for output. Defaults to ./p1files/LetterToUSDA.docx.

Returns

None. The contents of cipherfile’s text is embedded in fakefile’s whitespace and saved to savepath.

src.ch06.p1_invisible_ink.write_invisible(plaintext: list, ciphertext: list, template_path: str = None, filename: str = 'output.docx') → None

Embed ciphertext in plaintext’s whitespace.

Open a template file, template_path, with the needed fonts, styles, and margins. Write each paragraph in plaintext to the template file and add each paragraph in ciphertext to plaintext’s blank space. Save the new file as filename.

Parameters

• plaintext (list) – Paragraphs of a fake message in a list of strings (likely from get_text()).

• ciphertext (list) – Paragraphs of an encrypted message in a list of strings (likely from get_text()).

• template_path (str) – Absolute path to .docx file with predefined fonts, styles, and margins. Defaults to None. If not provided, defaults will be created.

• filename (str) – File name to use for output file. Defaults to output.docx.

Returns

None. plaintext is written to the file at template_path with ciphertext embedded in the blank space.

Raises

ValueError – If the number of blank lines in plaintext aren’t enough to embed ciphertext based on output of check_blanks().

Note

As of python-docx v0.8.10, creating custom styles isn’t well supported. More info here.

As a result, if a template isn’t provided, the default template is used.

Module contents

Chapter 6.