Steganography

Steganography

Khan, Mohammed Khan, Mohammed MinhajuddinMinhajuddin

What is Steganography?What is Steganography?

Stegosaurus: a covered lizard(but not a type of cryptography)

Greek Words:

STEGANOS – “Covered”

GRAPHIE – “Writing”

Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message.

This can be achieve by concealing the existence of information within seemingly harmless carriers or cover

Carrier: text, image, video, audio, etc.

Steganography, Cryptography, Steganography, Cryptography, and Watermarkingand Watermarking

There are two major branches of information hiding, Steganography and Watermarking

Watermarking: Communication in watermarking is the host signal, with the

embedded data providing copyright protection. The existence of a watermark is often declared openly. Any attempt to remove or invalidate the embedded content

renders the host useless.

Cryptography: Doesn’t conceal the communication. Scrambles the data to prevent eavesdroppers

understanding the content. Cryptography involves various methods and

implementations. May be considered complementary and orthogonal

(unrelated).

Once the presence of hidden information is revealed or even suspected, the purpose of steganography is defeated.

History of Steganography History of Steganography

Steganography ancient origins can be traced back to 440 BC, from the Histories of Herodotus

Demeratus sent a warning about a forthcoming attack to Greece by writing it on a wooden panel and covering it in wax.

Histiaeus, who shaved the head of his most trusted slave and tattooed a message on it. After his hair had grown the message was hidden. The purpose was to instigate a revolt against the Persians.

World War II

Invincible inks

Null ciphers (unencrypted messages):

Apparently neutral's protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects pretext for embargo on by products, ejecting suets and vegetable oils.

Sent by a German Spy in WWII, by taking the second letter in each word the following message emerges:

Pershing sails from NY June 1.

Microdot TechnologyShrinking messages down to the size of a dot became a popular method. Since the microdot could be placed at the end of a sentence or above a j or an i.

Modern Steganography Techniques

Masking and Filtering: Is where information is hidden inside of a image using digital watermarks that include information such as copyright, ownership, or licenses. The purpose is different from traditional steganography since it is adding an attribute to the cover image thus extending the amount of information presented.

Algorithms and Transformations: This technique hides data in mathematical functions that are often used in compression algorithms. The idea of this method is to hide the secret message in the data bits in the least significant coefficients.

Least Significant Bit Insertion: The most common and popular method of modern day steganography is to make use of the LSB of a picture’s pixel information. Thus the overall image distortion is kept to a minimum while the message is spaced out over the pixels in the images. This technique works best when the image file is larger then the message file and if the image is grayscale.

Basics of Modern SteganographySteganography

fE:     steganographic function "embedding"fE-1:   steganographic function "extracting"cover:  cover data in which emb will be hiddenemb:    message to be hiddenkey:    parameter of fEstego:  cover data with the hidden message

Important Requirement for Important Requirement for Steganographic SystemSteganographic System

Security of the hidden communication

size of the payload

Robustness against malicious and unintentional attacks

Steganography ToolsSteganography Tools

Detection of Steganographic Detection of Steganographic Content/CountermeasuresContent/Countermeasures

The detection of steganographically encoded packages is called Steganalysis.

Visual Analysis tries to reveal the presence of secret communication through inspection, either with the naked eye or with the assistance of a computer.

Statistical (Algorithmic) Analysis reveals tiny alterations in an image's statistical behavior caused by steganographic embedding.

The nominally universal methods developed to detect embedded stego-data are generally less effective than the steganalytic methods aimed at specific types of embedding.

Steganography Sample Steganography Sample WebsiteWebsite

Here is the link for Sample Steganographic tool Website:

http://mozaiq.org/

My QuestionsMy Questions

1. Salutations, Mr. Robertson of CIS 5371. The Florida Society of Math and Cryptography is proud to present you with an small exam for qualification into our society. The key for passing is studying. Cryptography is rigorous and only those with patience in themselves pass. We have an exam PO Box in Tallahassee. But please submit by 12/12.

AnswerAnswer

Salutations, Mr. Robertson of CIS 5371. The Florida Society of Math and Cryptography is proud to present you with an small exam for qualification into our society. The key for passing is studying. Cryptography is rigorous and only those with patience in themselves pass. We have an exam PO Box in Tallahassee. But please submit by 12/12.

The Cryptography exam key is in PO Box 1212.

2. Name three methods by which Modern day Steganography is accomplished?

Answer: Masking and Filtering Algorithms and Transformations Least Significant Bit Insertion

My QuestionsMy Questions