• Mạng máy tính 1 - Chapter 6: Electronic mail securityMạng máy tính 1 - Chapter 6: Electronic mail security

    Does not rely on certificate authorities in PGP every user is own CA ▫ can sign keys for users they know directly (certificates are like X.509) forms a “web of trust” ▫ trust keys have signed ▫ can trust keys others have signed if have a chain of signatures to them key ring includes trust indicators users can also revoke their keys

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  • Mạng máy tính 1 - Chapter 5: Digital signaturesMạng máy tính 1 - Chapter 5: Digital signatures

    (Step 1) Key generation: Every entity generates a public-private key pair ▫ choose a random private key ▫ compute the public key (Step 2) Registration: Every entity should ▫ provide proof of their identity (to the CA) (Step 3) Obtain certificate from the CA ▫ CA signs a certificate which binds the identity of A to A’s public key

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  • Mạng máy tính 1 - Chapter 4: Message authenticationMạng máy tính 1 - Chapter 4: Message authentication

    Sheart of the algorithm processing message in 1024-bit blocks consists of 80 rounds ▫ updating a 512-bit buffer ▫ using a 64-bit value Wt derived from the current message block ▫ and a round constant based on cube root of first 80 prime numbers

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  • Mạng máy tính 1 - Chapter 3: Public key cryptographyMạng máy tính 1 - Chapter 3: Public key cryptography

    Based on the difficulty of discrete log problem (like DH) All entities agree on a prime p (say 200 digits long) and a generator g Alice chooses a random value a as her private key (a < p also has typically the same number of digits as p) Alice compute α = ga mod p as her public key

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  • Mạng máy tính 1 - Chapter 2: Symmetric ciphersMạng máy tính 1 - Chapter 2: Symmetric ciphers

    Shave considered: ▫ Symmetric cipher model and terminology ▫ Classical ciphers ▫ Modern cipher techniques  block vs stream ciphers  Feistel cipher design & structure  DES details & strength ▫ Differential & Linear Cryptanaly

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  • Mạng máy tính 1 - Cryptography & network securityMạng máy tính 1 - Cryptography & network security

    Symmetric Cipher Model Classical Substitution Ciphers ▫ Caesar Cipher ▫ Monoalphabetic Cipher ▫ Playfair Cipher ▫ Polyalphabetic Ciphers ▫ Vigenère Cipher Cryptanalysis using letter frequencies

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  • Mạng máy tính 1 - Attacks overviewMạng máy tính 1 - Attacks overview

    DoS attack or DDoS is an attempt to make a computer resource unavailable to its intended users. Methods of attack ▫ ICMP flood ▫ Teardrop Attacks ▫ Peer-to-peer attacks

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  • Mạng máy tính 1 - Lecture 9: Socket programming with javaMạng máy tính 1 - Lecture 9: Socket programming with java

    DateTime Server import java.net.*; import java.io.*; import java.util.Date; public class DayTimeServer { public final static int daytimePort = 5000; public static void main(String[] args) { ServerSocket theServer; Socket theConnection; PrintStream p; try { theServer = new ServerSocket(daytimePort)

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  • Mạng máy tính 1 - Lecture 4: Wireless and mobile networksMạng máy tính 1 - Lecture 4: Wireless and mobile networks

    2.5 G systems: voice and data channels  for those who can’t wait for 3G service: 2G extensions  general packet radio service (GPRS)  evolved from GSM  data sent on multiple channels (if available)  enhanced data rates for global evolution (EDGE)  also evolved from GSM, using enhanced modulation  data rates up to 384K  CDMA-2000 (pha...

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  • Mạng máy tính 1 - Chapter 5: Link layer and lansMạng máy tính 1 - Chapter 5: Link layer and lans

    1. Every port is assigned a VLAN color. 2. Every MAC address is assigned a VLAN color. 3. Every layer 3 protocol or IP address is assigned a VLAN color.

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