Chapter 5 Secret Sharing Randomness Information hiding Secret

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Chapter 5 기타 주제들 Secret Sharing Randomness Information hiding

Chapter 5 기타 주제들 Secret Sharing Randomness Information hiding

비밀 공유 (Secret Sharing) Chapter 5 Other Topics 2

비밀 공유 (Secret Sharing) Chapter 5 Other Topics 2

암호에서의 난수 (Random Numbers) Chapter 5 Other Topics 9

암호에서의 난수 (Random Numbers) Chapter 5 Other Topics 9

정보 은닉 (Information Hiding) Chapter 5 Other Topics 20

정보 은닉 (Information Hiding) Chapter 5 Other Topics 20

l l A watermark is a design which is put into paper when it

l l A watermark is a design which is put into paper when it is made, and which you can only see if you hold the paper up to the light. Banknotes often have a watermark, to make them harder to copy illegally. Steganography is the art and science of writing hidden messages in such a way that no-one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity.

Steganography 예(1) l 이미지는 24비트로 색상을 표현: RGB l l 예 l l l

Steganography 예(1) l 이미지는 24비트로 색상을 표현: RGB l l 예 l l l 0 x 7 E 0 x 52 0 x 90은 이 색 0 x. FE 0 x 52 0 x 90은 이 색 반면에 l l l 8 bits for red, 8 for green, 8 for blue 0 x. AB 0 x 33 0 x. F 0은 이 색 0 x. AB 0 x 33 0 x. F 1은 이 색 하위 비트(Low-order bits)는 중요하지 않다! Chapter 5 Other Topics 29

Steganography 예(4) Non-Steganography Example l Walrus. html in web browser l View source Chapter

Steganography 예(4) Non-Steganography Example l Walrus. html in web browser l View source Chapter 5 Other Topics 32

Steganography 예(5) l stego. Walrus. html in web browser l View source l “Hidden”

Steganography 예(5) l stego. Walrus. html in web browser l View source l “Hidden” message: 110 010 110 011 000 101 Chapter 5 Other Topics 33