Internet Secure

key

• Secret key(密鑰）：ues the same key to Encryption and decryption（symmetric-key）對稱加密，須要絕對安全的空間來傳遞key
• Pulic kay(公鑰）：ues different key to Encryption and decryption （asymmetric-key)非對稱加密

Caeser Cipher(凱撒密碼）

• core：replace（替換思想）
  
  
  

Cryptographic Hash（又是可愛的哈希）

• Converting any length of input into a fixed length string or digest of information（任意長度輸入轉化爲固定長度二進制串）
• 哈希碰撞：Different inputs give the same result
• a good hash function:any tiny change --> a big change with digest
  

Hash for Password(使用哈希的密碼系統）

• Do not store the password you entered directly（非直接存密碼)
• store digest(存儲哈希值）
• 幾乎是不可逆
  
• share secret（共享密碼）
  在信息後面加上特定字符串，再哈希
  

Public Key Encryption Confidentiality

• base on two prime(從兩個素數開始）
• Public key:Open to the outside world for encryption(公鑰）
• Private key: Used for decryption, private ownership（私鑰）
• not perfect but it is hard to break
• Public keys can be distributed arbitrarily without protection(公鑰分發簡單）
• private keys are protected in computers or servers.

SSL(Secure Sockets Layer)安全套接字層

• Security for TCP
• Located between Application Layer and Transport Layer
• Because of the hierarchical structure, the underlying structure only needs to be responsible for the transmission of ciphertext (it is not known whether the transmission is ciphertext or plaintext).
  

TLS(Transpot Layer Security)

Digital Certificates（數字證書）

• Make sure the person you are talking to（確保談話對象）
• Amazon發公鑰給VerSign,VerSign計算驗證後，確實是Amazon,就返回一個帶簽名的公鑰
  
  
  
  
  
  

Summary