Pronunciation

Make sure you pronounce the following words properly:

covert ['kʌvət]  subtle ['sʌtl]  nefarious [nɪ'fɛərɪəs]  flourish ['flʌrɪʃ]  fraud [frɔ:d]  innocent ['ɪnəsənt]   unreadable [ֽʌn'ri:dəbl] medium ['mi:djəm]  analogy [ə'nælədʒɪ]  template ['templɪt]  categorize ['kætɪɡəraɪz] carrier ['kærɪə]  espionage [ֽespɪə'nɑ:ʒ]  technique [tek'ni:k]

Memorize the terms

1. Read the following terms and their definitions and memorize them:

carrier text - – place where secret message is kept

coin a term – invent and introduce

doodle – flourish, additional dash in the letter

grille cipher – cipher that can be decrypted using special grid put on the message hidden in the carrier text

retrieve the hidden text – restore, reconstruct the secret message

semagram – secret message where any symbols can be used except letters and figures

steganography medium – concept that includes hidden_message, carrier and steganography_key

2. Match the following words with their Russian equivalents.

digital watermarking	поразрядно идентичный
doodle	трафаретный шифр
cue code	сжатие с потерей данных
bit-for-bit identical	нулевой код
treat	ключевой код
null cipher	рассматривать
grille cipher	дополнительный штрих в букве
lossy compression	нанесение (цифровых) водяных знаков (меток)

3. Match the following words with their synonyms.

covert communication	side
nefarious application	simulation, imitation
intend	built in
microdot	secret, stealthy interaction
(spam) mimic	deception, cheating
party	tiny photograph
embed	be about, be going to
(financial) fraud	dishonest, corrupt using

Reading

4. Pre-reading task.

Look at the title of the text. What information do you expect to read here?

What would you like to know about steganography?

Where have you met steganographic techniques?

5. Text 1. Read the text and give brief characteristics of the main steganographic techniques.

Steganography.

Steganography is the art of covered or hidden writing. The purpose of steganography is covert communication to hide a message from a third party. This differs from cryptography, the art of secret writing, which is intended to make a message unreadable by a third party but does not hide the existence of the secret communication. Although steganography is separate and distinct from cryptography, there are many analogies between the two, and some authors categorize steganography as a form of cryptography since hidden communication is a form of secret writing. Nevertheless, this paper will treat steganography as a separate field.

Although the term steganography was only coined at the end of the 15th century, the use of steganography dates back several millennia. In ancient times, messages were hidden on the back of wax writing tables, written on the stomachs of rabbits, or tattooed on the scalp of slaves. Invisible ink has been in use for centuries—for fun by children and students and for serious espionage by spies and terrorists. Microdots and microfilm, a staple of war and spy movies, came about after the invention of photography.

Steganography hides the covert message but not the fact that two parties are communicating with each other. The steganography process generally involves placing a hidden message in some transport medium, called the carrier. The secret message is embedded in the carrier to form the steganography medium. The use of a steganography key may be employed for encryption of the hidden message and/or for randomization in the steganography scheme. In summary:

steganography_medium = hidden_message + carrier + steganography_key

Figure 1 shows a common taxonomy of steganographic techniques.

• Technical steganography uses scientific methods to hide a message, such as the use of invisible ink or microdots and other size-reduction methods.