Blowfish Cryptosystem
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This document discusses the Blowfish encryption algorithm and the Nmap network scanning tool. It begins with an outline of the topics to be covered, which include an introduction to Blowfish, its structure and cryptanalysis, a paper on modifying Blowfish using multiple keys, and an overview of Nmap including its features and usage for port scanning networks. The document provides technical details and code examples for how Blowfish encryption works, discusses its security and comparisons to other algorithms, and outlines how Nmap can be used to detect operating systems, services, and vulnerabilities on targeted systems.
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http://upload.wikimedia.org/wikipedia/en
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Addition is mod 232
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Blowfish Cryptosystem
- 1. FACULITY OF ELECTRONIC TECNOLOGY COMPUTETR ENGINEERING (MSc) By: Haitham Farag Daw 1 Cryptography andCryptography and Network SecurityNetwork Security
- 2. OutLine 2 Blowfish Encryption Algorithm Paper Search Nmap Tool
- 3. Blowfish Encryption Algorithm 3 -----------------------------------------------------------------
- 4. Main point Introduction Structure Cryptanalysis Comparison References 4
- 5. Introduction designed in 1993 by Bruce Blowfish 64-bit block cipher with variable length key Large key-dependent S-boxes More resistant to cryptanalysis Key-dependent permutations Diverse Mathematical Operations Combine XOR and addition 5
- 6. Continue Fast Compact It can run in less than 5K of memory. Simple to code Easily modifiable for different security levels Secure: The key length is variable ,it can be in the range of 32~448 bits: default 128 bits key length. Unpatented and royality-free. 6
- 7. Structure of BF Feistel iterated block cipher Scalable Key (32 to 448 bits) Simple operation that are efficient on microprocessors XOR, Addition, Table lookup, etc Employ Precomputable Subkeys Variable number of iterations 7
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- 9. Implementation: Encryption ( ) 171617 181617 11 111 PRR PLL PLR RPLFL iii iiii ⊕= ⊕= ⊕= ⊕⊕= −− −−− Wikipedia, http://en.wikipedia.org/wiki/Image:BlowfishDiagram.png Arrays: P – Number of rounds + 2 elements 4 S-boxes – 256 elements 9
- 10. Implementation: Function F(x( ( ) [ ] [ ]( ) [ ]( ) [ ]07 81516232431031 4 321 − −−−− + ⊕+= XS XSXSXSXF Wikipedia, http://upload.wikimedia.org/wikipedia/en /8/81/BlowfishFFunction.png Addition is mod 232 10
- 11. Data Encryption • Divide 64-bits into two 32-bit halves: XL, XR • For i = 1 to 16 o XL = XL XOR Pi o XR=F(XL) XOR XR o Swap XL and XR • Swap XL and XR (Undo the last swap ) • XR=XR XOR P17 • XL = XL XOR P18 • Concatenate XL and XR 11
- 12. Cryptanalysis Differential Attack After 4 rounds a differential attack is no better than a brute force attack Weak Keys S-box collisions blowfish algorithm has yet to be cracked as the key size is high, requires 2448 combinations 12
- 13. Future Concerns Simplifications Fewer and Smaller S-boxes Fewer Iterations On-the-fly subkey calculation Twofish AES Finalist 128-bit Block Size More Operations 13
- 14. Comparison 14
- 15. References Wikipedia (for illustrations) http://en.wikipedia.org/wiki/Blowfish_cipher Applied Cryptography Bruce Schneier John Wiley and Sons, Inc. 1996 The Blowfish Paper http://www.schneier.com/paper-blowfish-fse.html 15
- 17. New Approach for Modifying Blowfish Algorithm by Using Multiple Keys by Afaf et al in VOL.11 No.3, March 2011, Amman, Jordan, Baghdad, Iraq 17
- 19. Outline Introduction Port Scanning Nmap Anti-Port Scanning Reference 19
- 20. Introduction IP Addresses: Finding out an IP Address Through Instant Messaging Software Through Internet Relay Chat Through Your website Through Email Headers 20
- 21. 21 Port Scanning Port Scanning is normally the first step that an attacker undertakes. List of Open Ports Services Running Exact Names and Versions of all the Services or Daemons. Operating System name and version
- 23. Major Tools Available Some of the best and the most commonly used Port Scanners are: Nmap Superscan Hping Nessus Common Features of all above Port Scanners: Very Easy to Use Display Detailed Results 23
- 24. Nmap Nmap (Network Mapper) is a security scanner originally written by Gordon Lyon , (1997). Is a free and open source, Website nmap.org. Nmap runs on all major computer operating systems Used to discover hosts and services on acomputer network, and security auditing Thus creating a "map" of the network. 24
- 25. 25 Determain what.. operating systems vulnerability detection. It was designed to rapidly scan large networks Nmap is also capable of adapting to network conditions including latency and congestion during a scan Nmap sends specially crafted packets to the target host and then analyzes the responses.
- 26. Nmap features Host discovery Port scanning Version detection OS detection Nmap can provide further information on targets, including reverse DNS names, device types, and MAC addresses. 26
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- 30. Anti-Port Scanning Some useful Anti-Port Scanning software available are: Scanlogd BlackICE Snort Abacus Port sentry And multi tools using to hide the IP address . 30
- 31. Reference http://nmap.org/book/man.html http://nmap.org/book/install.html http://nmap.org/nsedoc [email protected] 31