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Basic Internet Security Concepts

Basic Internet Security Concepts. J.W. Ryder RyderJ@Oneonta.Edu. Introduction. The internet is a vast wilderness, an infinite world of opportunity Exploring, e-mail, free software, chat, video, e-business, information, games Explored by humans. Internet Security Concepts.

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Basic Internet Security Concepts

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  1. Basic Internet Security Concepts J.W. Ryder RyderJ@Oneonta.Edu 04-01-98 J.W. Ryder

  2. Introduction • The internet is a vast wilderness, an infinite world of opportunity • Exploring, e-mail, free software, chat, video, e-business, information, games • Explored by humans 04-01-98 J.W. Ryder

  3. Internet Security Concepts • Introduction of several basic security concepts • General mechanisms for protection 04-01-98 J.W. Ryder

  4. Sniffing and Spoofing • [1] • Sniffing • The ability to inspect IP Datagrams which are not destined for the current host. • Spoofing • After sniffing, create malicious havoc on the internet 04-01-98 J.W. Ryder

  5. 1 Unprotected Internet node Private Network node Gabrielle Poirot (C) Secure Gateway node A Guy Bank (I) Steve Burns (C) Sears Wall Street (N) A Guy’s Swiss Bank Ramon Sanchez (A) 04-01-98 J.W. Ryder

  6. A Guy has no integrity • Swiss Bank Scam • Integrity - The guarantee that, upon receipt of a datagram from the network, the receiver will be able to determine if the data was changed in transit 04-01-98 J.W. Ryder

  7. Ramon springs for sound • Sears solid state stereos • Authentication - The guarantee that, upon receipt of a datagram from the network, the receiver will be able to determine if the stated sender of the datagram is, in fact, the sender 04-01-98 J.W. Ryder

  8. A guy sniffs success • Gabrielle and Steve almost strike it rich • Confidentiality - Ensure that each party, which is supposed to see the data, sees the data and ensure that those who should not see the data, never see the data. 04-01-98 J.W. Ryder

  9. Wall Street Woes • A guy spots a hot stock tip • Non-repudiation - Once a host has sent a datagram, ensure that that same host cannot later claim that they did not send the datagram 04-01-98 J.W. Ryder

  10. A guy becomes desperate • Bring Wall St. to its knees • Denial of Service Attack - Flood a given IP Address (Host) with packets so that it spends the majority of its processing time denying service 04-01-98 J.W. Ryder

  11. 2 One Way Hash Functions (MD5, SHA1) Application In Comm. Stack Key Mgmt. Functions IP Crypto Functions (DES, CDMF, 3DES) Physical Adapter 04-01-98 J.W. Ryder

  12. Protocol Flow • [2, 3] • Through layers, each layer has a collection of responsibilities • ISO OSI Reference Model - (Open Systems Interconnection) • IP Datagram 04-01-98 J.W. Ryder

  13. 3 IP Hdr. Data IP Datagram Data MAC Fn Digest MAC Function IP Hdr. Data Digest Integrity 04-01-98 J.W. Ryder

  14. Keys • Bit values fed into cryptographic algorithms and one way hashing functions which provide help provide confidentiality, integrity, and authentication • The longer the better - 40, 48, 56, 128 • Brute force attacks can win with small keys 04-01-98 J.W. Ryder

  15. Symmetric Keys • Have qualities such as life times, refresh rates, etc. • Symmetric - Keys that are shared secrets on N cooperating, trusted hosts 04-01-98 J.W. Ryder

  16. Asymmetric • Public / Private key pairs • Public key lists kept on well known public key servers • Public key is no secret. If it is, the strategy will not work. • Public and Private keys inverse functional values • Private key is only known to you and must remain secret 04-01-98 J.W. Ryder

  17. Concept • Sender encrypts data with private key • Receiver decrypts data with public key • Receiver replies after encrypting with public key • Sender receives response and decrypts with private key 04-01-98 J.W. Ryder

  18. 4 Data Crypto Fn. Encrypted Data Key Encryption Function Encrypted Data IP Hdr. Confidentiality 04-01-98 J.W. Ryder

  19. 5 Encrypted Data Crypto Fn. Data Key Decryption Function Data Confidentiality 04-01-98 J.W. Ryder

  20. MACs • Message Authentication Codes, One Way Hashing Functions • A function, easy to compute but computationally infeasible to find 2 messages M1 and M2 such that • h (M1) = h (M2) • MD5 (Rivest, Shamir, Adleman) RSA ; SHA1 (NIST) • MD5 yields a 128 bit digest [3] 04-01-98 J.W. Ryder

  21. DES • Data Encryption Standard • U.S. Govt. Standard • 56 bit key - originally 128 bits • Absolute elimination of exhaustive search of key space • U.S. Security Agency Request - Reduce to 56 bits • Export CDMF (40 bits) • Keys are secrets to algorithms, not algorithms themselves [4, 5] 04-01-98 J.W. Ryder

  22. Encrypted Data IP Hdr. Digest Confidentiality & Integrity Digital Signature (Enc. Digest) Encrypted Data IP Hdr. Confidentiality, Integrity, & Authentication 04-01-98 J.W. Ryder

  23. Data CF EM DS MAC Key Digest MAC_Time < CF _Time Why would a guy prefer a Digital Signature over a Keyed Digest ? Why not? What types of Security are provided with EM, DS, Digest, Keyed Digest? Keyed Digest 04-01-98 J.W. Ryder

  24. No Security Integrity Confidentiality Conf. & Integrity Integrity & Auth. Conf., Int., & Auth. Integrity & Auth. Conf., Int., & Auth. Msg Msg MD EM EM MD Msg DS EM DS Msg KD EM KD 04-01-98 J.W. Ryder

  25. Purpose • Some ideas on Internet Security • Classes of mischief on Internet, definitions • Tools to fight mischief • Combinations of these tools 04-01-98 J.W. Ryder

  26. Purpose continued • Very high level • Good starting point for further study about • General networking & strategies • Cryptography • Key Management • Algorithm Analysis 04-01-98 J.W. Ryder

  27. Post Presentation Results • Should be familiar with concepts & terms such as • Integrity, Authentication, Non-repudiation, Confidentiality • Keys, MACs, Cryptography, Digest, Digital Certificates, Datagram • High level understanding of some methods to combat some the above types of Internet mischief 04-01-98 J.W. Ryder

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