재안 IT 공부 일기장

[6] AI for Security Anomaly Detection - Find rare items or events which deviate significantly from the majority of the data. - Define normal events. - No need of data on faulty actions(behaviors). - Point Anomaly - Context Anomaly - Collective Anomaly @Point Anomaly - A single instance of data is anomalous if it's too far off from the rest. @Contextual Anomaly - The abnormality is context specif..

[5] AI Security [5-1] AI 강화를 위한 보안 [5-2] 보안 강화를 위한 AI [5-1] AI 강화를 위한 보안 AI 동작 절차 - 1. Dataset - 2. Training - 3. Model creation - 4. Predictions - 5. Service Deep learning 기술의 한계 - 매우 많은 학습 데이터가 필요하다. - 결과에 대한 인과 관계 표현 능력이 부족하다. - 예외 상황에 대한 처리가 불가능하다. Adversarial Examples - 적대적 사례 - 인간의 눈에 보이지 않는 noise를 섞은 이미지 - 예측 단계에서 AI 모델을 쉽게 속일 수 있다. Fast Gradient Sign Method - 적대적 공격 방법 - 학습 방향의 반대 방향으로 노..

[4] Business Chances of Blockchain Block이란? - Record of state change - Consisting of hash, answer, and transactions - Hash : Summary of previous transaction information - Answer : Value used for hash calculation - Transaction : 거래정보 - Transaction records are stored in blocks. Blockchain이란? - A fully distributed P2P software network - That uses encryption to secure host applications, stores data,..

[3] Symmetric Encryption and Message Confidentiality (AES) Stream Ciphers - Faster and use far less code. - Key is used to produce stream of Pseudo-Random Sequence Generation. - XOR keystream output with plaintext bitstream. - Encryption sequence should have a large period, large enough to ensure no repetition. - Keystream approximates random number properties. - Should use a sufficiently long k..

[2] Symmetric Encryption Message Confidentiality [2-1] Block Cipher Structure [2-2] Data Encryption Standard [2] Symmetric Encryption Message Confidentiality conventional encryption, secret-key or single-key encryptionplaintext, encryption algorithm, secret key, ciphertext, and decryption algorithm Cryptanalysis - Only weak algorithms fail a ciphertext-only attack - Usually design algorithms to ..

[1] Classic Encryption Techniques [1-1] Substitution cipher [1-2] Transposition cipher [1-1] Substitution cipher Monoalphabetic Cipher Caesar Cipher - Monoalphabetic Cipher : mapping plaintext character one-to-one with other characters - Assign numbers from 0 to 25 to english character and combine them with a secret key to perform a modulo operation - K : secret key (shift interval of plaintext)..

[6] Buffer Overflow prevention techniques는 알려져 있으나 코드가 너무 커짐 legacy code나 careless programming으로 인해 뚫림 BufferOverflow basics more data to be stored thant capacity (fixed sized buffer) - stack - heeap - global data 인접하고 있는 메모리를 overwrite - corruption of program data - unexpected transfer of control - memory access violation - execution of code chosen by attacker 사실 구현하기 존나 빡센 공격 방식이다 결국 메모리를 덮어써야..

[5] Malicious Software Malware Programs exploting (이용) system vulnerabilities known as malicious software or malware T1 : program fragments that need a host program (viruses, logic bomb, and backdoors) T2 : independent self-contained programs (worms, bots) T3 : replicating or not malware can be classifited into 2 broad categories 1. how it spreads or propagates 2. the actions or payloads it perf..

[4-2] 운영체제 보안 각 OS계층은 아래의 계층을 통해서 들어오는 공격에 취약하다. 설치 프로세스중 오염될 수도 있다 시스템을 구상할때는 이러한 위협요소들을 고려해야한다. System Security Planning maximize security while minimizing costs - access control - how to authenticate - who administers - how to manage Operating Systems Hardening 1. secure the base operating system - install and patch os 초기엔 제일 필요한거만 설치 추후 필요한 거를 조심해서 설치(device driver code) 최신상태로 유지하기 - remove ..

[4] 데이터베이스 보안 Database System and DBMS 데이터 종류: 1. integrated data : non-duplicated, 여러군데 분산된 데이터  2. stored data : 데이터셋 3. operational data : 조직 고유의 업무용도 4. shared data : 데이터 통합관리의 용도 Database System relationships between data items and groups of data items DBMS database management Query Language : provides a uniform interface to the database - Data Definition Language - Data Manipulation Langua..