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Network security

Network security. Jesper Holt Nielsen. Network Security. Basic concepts Symmetric Encryption Assymetric Encryption User authentication Public and shared keys Security in networks. Basic security goals. Integrity , Availability , and Confidentiality Authenticity

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Network security

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  1. Network security Jesper Holt Nielsen

  2. Network Security • Basicconcepts • SymmetricEncryption • AssymetricEncryption • Userauthentication • Public and sharedkeys • Security in networks

  3. Basicsecuritygoals • Integrity, Availability, and Confidentiality • Authenticity • Genuine and verified • Accountability • Logging, trace breach’s • Violete transmission of information • Computer Security • Internet Security • Virus • Attacks/hacks

  4. Basicsecurityconcepts • KeyInterchange / KeyEncryption • Private-key • Public-key • One-way Hash • Public-keyEncryption • Hashing

  5. Conceptschallenges • Designer vsattacker • Investments • Oftenlittlebenefit, untilfailure • Monitoring • Ressource heavy

  6. OSI securityarchitecture • A standard architecture for securitymeans • A definition of the requirements • Consists of three major parts • Security attacks • Services • Mechnisms • Standards X.800, RFC 2828

  7. OSI securityarchitectureSecurity attacks • Passive • Eavesdroppen, monitoring transmission • Difficult to detect • Active • Modification, creation, DoS • Easy to detect, hard to avoid

  8. OSI securityarchitecture Services • Authentication • Are you who you claim? • Access Control • Unauthorized use • Data Confidentiality • Protection of data • Data Integrity • Is the data correct? • Nonrepudiation • Protection against denial

  9. OSI securityarchitecture Mechanisms • Specific security mechanisms • Can be incorporated into protocol layers • Digital signature • Access control • Data integrity • Authentication exchange • Pervasive security mechanisms • Not specific to any layer or protocol • Trusted functionality • Security label • Event detection • Recovery

  10. Cryptographic hash functions • Arbitrary block of data -> returns a fixed-size bit string • Encoded data is the message • Hash value is the message digest or digest • Functions MD5, SHA-1 • Weakness • Collision • m1 ≠ m2 and hash(m1) = hash(m2)

  11. Hashing properties • Easy to compute the hash value for any given message • Infeasible to generate a message that has a given hash • Infeasible to modify a message without changing the hash • Infeasible to find two different messages with the same hash.

  12. Why hashing? • Digital signatures • Message authentication codes (MACs) • Integrity of a message • Altering the message • Verify issuer • Fingerprints a message • Cant be altered

  13. Symmetricencryption • Conventional Encryption method • Secret-key concept • Single-key Encryption • Same key for en- and decryption • DES, 3DES, AES • Blockand Stream Cipher • Random and pseudo-random numbers

  14. Symmetric encryption structure • Plaintext • Encryptionalgorithm • Secretkey • Ciphertext • Decryptionalgorithm

  15. Symmetric model

  16. Random and pseudo-randomnumbers • PRNGs, TRNGs and PRFs

  17. Public-key Cryptography • AssymetricEncryption • Twoseperate keys • Public-keyand Private-key • Encryptplaintext, decryptciphertext • Keydistributions • Digital Signatures • Verify a message

  18. Public-key Cryptography

  19. Implementations • RSA - Rivest, Shamir & Adleman of MIT in 1977 • Widely used • All users generate a private and public key pair • Publish their public key • Keep private key secret

  20. Thankyou

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