Authentication in Wireless Networks


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My research topic on "Noordelijke Hogeschool Leeuwarden"

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Authentication in Wireless Networks

  1. 1. DEIOCAuthentication in wireless networks Ludo Stoetenga Chris van den Berg Noordelijke Hogeschool Leeuwarden
  2. 2. DEIOCIntroduction ProjectObjectives Choices – Network type – Standards Types of Connections Encryption methods Conclusion
  3. 3. DEIOCProject Objectives Investigate through documents and lecture studies about the subject and write a theoretical description about this. Implement one of the encryption methods in a Java based environment. Write a document how we implemented the authentications in Java.
  4. 4. DEIOCChoices Network types – TTP (Trusted Third Party) – Location Limited – Chain of Thrust Standards – 802.11b (Wi-Fi) – 802.16 (Broadband Wireless Metropolitan Area Networks)
  5. 5. DEIOCTTP (Trusted Third Party)A server that is trusted by the clients The server defines the protocol for secure connections. TTP Client A Client B
  6. 6. DEIOCWireless There are two standards 802.11 802.16 Wi-Fi  MAN Authentication  Authentication – Open Key – Open Key – Shared Key – Shared Key Encryption  Encryption – RC4 – RSA – TripleDES
  7. 7. DEIOCConnections Client connect with the TTP for the first time Client connect with a different Client
  8. 8. DEIOCClient connect with the TTP Client TTP Given a password (on a paper) Agree on secret key by Diffie-Hellman key agreement Send given password (encrypted with secret key) Send new password (encrypted with secret key)
  9. 9. DEIOCClient connect with a different Client Client A Agree on Connection Client B TTP Get keys from the TTP encrypted with Shared Secret key Send data encrypted with the keys provided by the TTP
  10. 10. DEIOCEncryption methods Diffie-Hellman key agreement Lamport Scheme RSA RC4 TripleDES
  11. 11. DEIOC Diffie-Hellman key agreement A B A and B agree on: P (prime) and G (1 > g > p)Gen X (0 > x > p-1) Gx Gen Y (0 > x > p-1) Gy A and B can both Compute Gxy Gxy is the Shared secret Key
  12. 12. DEIOCLamport scheme Shared secret key 40-bits keyShared Secret Key One way function New Shared Secret Key Key (40 bits)
  13. 13. DEIOCRSA• 2 large primes P and Q• Compute N = P * Q and F = (P-1)(Q-1) • N modules• Select Random: E, 1 < E < F ( gcd(E,F)=1 ) • E Encryption exponent• Select Unique: D, 1 < D < F ( E * D = 1 (mod F) • D Decryption Exponent A B Send N, E C = ME mod N M = CD mod N
  14. 14. DEIOCRC4 A B Shared secret KeyEncrypt Plain Text with Secret Key Cipher Text Decrypt Cipher text with Secret Key • RC4 uses a variable length key from 1 to 256 bytes • The stream cipher uses swap and modulate operations to encrypt
  15. 15. DEIOCDES A B Shared secret Key Cipher Text Encryption L0 L1 L16Input output IP FP R0 L0 + F(R0,key1) L15 + F(R15,key16) Decryption is simply the inverse of encryption, following the same steps as above, but reversing the order in which the subkeys are applied. Blocksize is 64 bits
  16. 16. DEIOCTripleDES Triple-DES is just DES with two 48-bit key array’s applied in 3 rounds Encryption Encrypt (key 1) Decrypt (key 2) Encrypt (key 1) Decryption Decrypt (key 1) Encrypt (key 2) Decrypt (key 1)
  17. 17. DEIOCConclusion Encryption methods are not secure – Methods are insecure – Errors by programming Standards – RC4 – RSA – TripleDES