Shift shift key25 Exhaustive search Substitution Cipher Substitution
Shift 사이퍼 단순한 연산에(shift) 의한 사이퍼 #key=25 Exhaustive search
Substitution Cipher(대체암호) Substitution Cipher.
Playfair 1차세계대전(영국) • plaintext “hello”
암호의 분류 스테가노그래피 (Steganography) 비밀 통신 크립토그래피 (Cryptography) 암호학(Cryptology = Cryptography + Cryptanalysis)의 영역 9
Cryptography vs Steganography Cryptography: with Greek origins, means “secret writing. ”. The science and art of transforming messages to make them secure and immune to attacks. Steganography with origin in Greek, means “covered writing, ” in contrast with cryptography, which means “secret writing. ” 10
More Steganography In October 2001, the New York Times published an article claiming that al-Qaeda had used steganography to encode messages into images, and then transported these via e-mail and possibly via USENET to prepare and execute the September 11, 2001 terrorist attack 11
인증방식 인증의 방식 What you have? ü 열쇠, 출입카드 What you know? ü PWD, passphrase, PIN What you are? ü Something you are: 홍체, 지문 ü Something you do: 음성, 서명 혼합방식 ü What you are + What you know, What you have+ What you know – 인증서, 지문+PIN 21
해쉬함수 10101010101010101101010100101011010010010111010001010111010010010111000100010 1101001010111010001010001010101010101000000111111101101010101001011010101011 111100001010101001010100111010011010101010101010101010010111100001110100011110011101010101010110010101010001010111001010000010100111001010101110101010110101010010101101001001011101000101011101001001011100010001011010010101110 1000101000101010101010100000011111110110101010100101101010101111110000101010010101001110100110101010101010101010100101111000011101000110001111001110 101010101010110010101010001010111001010000010100111001010101110101010101010 101101010100101011010010010111010001010111010010010111000100010110100101011101000101010101010100000011111110110101010100101101010101111110000101010100101010011101001101010101010101010101001011110000111010001100011110011101010101100101010100010101110010100000101001110010101011101010101010101011010101 01001010110100100101110100010101110100100101110001000101101001010111010001010001010101010000001111111011010101010010110101010111111000010101010010101001110100110101010101010101010100101111000011101000110001111001110101010101011001 01000101000010101110010100000101001110010101011·········· 010101010101011010101010101011101101010100101010111 HAS-160, SHA-1 의 경우 160 비트 출력 110100010100010101010101010000001111111011 29
Q&A 41
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