요약
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목차

• 0925 - http VS https
  • ✅ What is HTTP
  • ✅ What is HTTPS
    • SSL/TLS’s Role
  • ✅ conclusion
• 1001 - cookies, sessions, tokens
  • ✅ Cookie
  • ✅ Sessions
  • ✅ Token
    • JWT (JSON Web Token)
• 1015 - Browser Storage
  • ✅ Cookies
  • ✅ Local Storage
  • ✅ Session Storage
  • ✅ IndexedDB \& Cache Storage
• 1015 - Symmetric key ciphers and asymmetric key ciphers
  • ✅ Introduction - Why We Need Encryption
  • ✅ Symmetric Encryption
  • ✅ Asymmetric Encryption

0925 - http VS https

Summery
http & https : protocol - the way the web browser and server communicate

✅ What is HTTP

• standard protocol for exchanging information on the web
• structure : ( broser(request) → server(response)) : Html, image, data…
• problem : Unencrypted and sent to Plain Text

Unencrypted : 암호화 되지 않음

✅ What is HTTPS

• Http + security(-S) Certificate (SSL/TLS)
  • https is a protocol with a security certificate added to http.
• protect http communications with SSL/TLS encryption
• Gain data integrity : data is not tampered with in the middle
• so, Even if the communication is intercepted, the content is unknown > only encrypted data is visible

SSL/TLS’s Role

SSL : Secure Sockets Layer
TLS : Transport Layer Security (standard)

• Encryption : no one else can see the content
• Authentication : Proof that the server is real
• Integrity : Ensure data is not tampered with

Certificate : 인증서   /   encryption : 암호화   /   gain : 얻다

integrity : 청렴 , 무결성셔 (not loss : 손실 X)   /   tampered : 참견하다

Even if : ~ 하게 되더라도   /   intercepted : 가로채다   /   encrypted : 암호화된

✅ conclusion

• HTTP has announced the start of the web, but there are too many security problems
• In the future, HTTPS will be used instead of HTTP, and the web without security will gradually disappear

integral : 없어서는 안 될   /   gradually : 점진적으로

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1001 - cookies, sessions, tokens

typical ways a server authenticates a client

typical : 대표적인

✅ Cookie

• string information in the form of key-value, stored in the client browser
• method of - identifying users, by sending cookies together on request

advantages
simple way to implement

disadvantages
be weak in security & Capacity limits exist
cookie size increases → Network load occurs

identifying : 식별하다   /   implement : 도구, 수단

✅ Sessions

Manage sensitive information on the server side
Store session ID only in cookie form on client

advantages
Safer management than cookies

disadvantages
Risk of session ID hijacking
Requires session storage on the server

manage : 관리하다 (계획, 통제의 느낌)   /   handle (유사어) : 어떤 문제를 직접 처리하다. (즉각적인 상황)

hijacking : 납치하다, 강탈하다

✅ Token

• once the client is authenticated to the server, the server issues a Token (informed value)
• client presents this token on each request to prove authentication

advantages
stateless characteristic : it does not maintain the state
Minimize DB inquiry

disadvantages
Payload is simple encoding and cannot store sensitive information
Difficult to deal with token takeover

issues : 발급하다, 발행하다   /   informed : 정보를 제공하다

stateless : 무상태 - 과거의 기록을 기억하지 않고 그때그때 정보만 바로 처리한다.

inquiry : 조회   /   sensitive : 민감한 ; deal : 대처하다   / &nbsp takeover : 탈취

JWT (JSON Web Token)

JSON-based token with authentication information

• structrue: Header.Payload.Signature
  • Header: Define which algorithm to sign
  • Payload: Information Required for Authentication
  • Signature : combines Header and Payload with SecretKey

advantages
can block forgery through Signature verification

forgery : 위조 / 도용

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1015 - Browser Storage

Last time, we talked about cookies, sessions, and tokens (that manage status/authentication with servers.)
In this session, we will present about browser storage.
Browser storage is a method of storing directly in a client (browser).

storing : 저장 (n)   /   directly : 직접적으로(n)

✅ Cookies

Oldest method used by server/client together

• Capacity: ~4KB
• Mainly used for session maintenance, ad tracking

• But, Security issues (XSS, CSRF)

  • XSS : (Cross-site script) : vulnerability where an attacker’s embedded script runs in a user’s browser.
  • CSRF : (Content Security Policy) : attack that exploits the authentication of a logged-in user (to execute an unwanted state change request.)

Oldest : 가장 오래된   /   Mainly : 주로   /   Vulnerability : 취약

embedded : 끼워 넣어지다   /   exploits : 이용하다

✅ Local Storage

• Domain units, persistent storage (remains if not cleared)
• Capacity: 5-10 MB
• can only store string
  • ex) Set dark mode, maintain language selection

persistent : 영구적인   /   exploits : 이용하다   /   abstract : 추상적인

✅ Session Storage

• Similar to Local Storage, but per tab
• Disappear when tab is closer
  • If you close the tab during payment, it will fly

✅ IndexedDB & Cache Storage

IndexedDB

• Large Data Storage (Hundreds of MB or more)
• Structured data, transaction support
• Asynchronous Processing
  • Gmail Offline Mode

Cache Storage

• Save network request/response objects
• Can provide resources offline

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1015 - Symmetric key ciphers and asymmetric key ciphers

✅ Introduction - Why We Need Encryption

Encryption is one of the most essential technologies to protect our data
when we send information over the internet - like passwords, messages - it passes through many servers and networks.
Without encryption, anyone could intercept and read that data.
To avoid this risk, data is encrypted and transmitted.

In modern networks, there are two main types of encryption:
symmetric and asymmetric.

over : ~를 통해서   /   pass (through) : 통과하다,지나가다

✅ Symmetric Encryption

The same key is used for both encryption and decryption.
In symmetric encryption, the sender and receiver share one secret key.
The sender uses this key to encrypt the data, and the receiver uses the same key to decrypt it.
Therefore, the sender and receiver must share the same key in advance

feature

Because it uses only one key, symmetric encryption is fast and efficient, But key transfer is difficult
If the key is leaked, all the data becomes dangerous.

used for both + N : 둘 다에 사용되다   /   in advance : 사전에   /   leaked : 유출되다

✅ Asymmetric Encryption

Uses a pair of keys — a public key and a private key.

• The public key can be shared with anyone

used for both + N : 둘 다에 사용되다   /