General information
The function of “AGUTA Text Encrypter” software is encrypting and decrypting of text information. The encrypted text is embedded into a bitmap image file of BMP format. The image file size stays the same after encryption, as the encrypted text is written directly into the image color components.

Cryptographic method
Besides the source text is broken into individual bits and is spread across the image, the text also gets encrypted beforehand with a ciphertext, for which the key is the password you have entered. The longer password you enter, the less are the chances for the attacker to reveal the original text.
If the password is not specified, encryption is still performed, but using a fixed key. Please note that encrypting large texts (more than 100KB) will require a significant time. Time is what you have to pay for the safety of your information.

Editing text
The primary window of the program is a simple text editor much alike standard Notepad editor. “File” menu contains the following commands:

• “New” (Ctrl + N) – create a new empty document.
• “Open” (Ctrl + O) – open a text document.
• “Save” (Ctrl + S) – save text to file.
• “Save As…” – save text under new filename.

The main text editing operations can be accessed in “Edit” menu:

• “Cut” (Ctrl + X) – cut the selected block into clipboard.
• “Copy” (Ctrl + C) – copy the selected block into clipboard.
• “Paste” (Ctrl + V) – paste the clipboard text into the current cursor position.
• “Select All” (Ctrl + A) – select all text.

Besides, editor service functions are available, located in the “Services” menu:

• “Font…” – change the text font. The change is applied to the whole text.
• “Background…” – change the background color in the text editor.
• “Word Wrap” – switch between word wrap mode and normal mode. When in word wrap mode, long lines are broken into several lines. This ensures horizontal scrollbar is not displayed.
• “Hidden” – toggles hidden text mode. In this mode, the text field disappears, which keeps eavesdropper from peeping the text you are editing.

Loss of image quality
If the text is small, only 1 bit of color components will be required to embed the text into an image. This means the image will visually stay intact.
However, encrypting large texts may require substituting 2 or more bits. Substituting more than 3 bits will cause image changes that are recognizable for human eye, stains may appear or the sharpness may decrease.
As many as 6 or 7 bits substituted will result in so much noise that the image will only retain general outlines of objects depicted. If the encryption will require 8 bits, one should note that the image will become a meaningless set of colors and the loss of recognition will be close to 100%. Encrypting into an image with 256 color palette will cause substantial changes even with 1 bit of color components substituted.