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Public key cryptography: a practical Public key cryptography: a practical approach approach Israel Herraiz <isra@herraiz.org> <israel.herraiz@upm.es> KeyID FE0A7AF3 Fingerprint D0DA E915 BFDD E5CD 8BA0 B159 7E97 2ACB FE0A 7AF3

  1. Public key cryptography: a practical Public key cryptography: a practical approach approach Israel Herraiz <isra@herraiz.org> <israel.herraiz@upm.es> KeyID FE0A7AF3 Fingerprint D0DA E915 BFDD E5CD 8BA0 B159 7E97 2ACB FE0A 7AF3 Slides and additional info at http://mat.caminos.upm.es/~iht/pkc/ 1 http://herraiz.org

  2. Privacy in electronic communicatios Privacy in electronic communicatios Can we ensure privacy in electronic communications? 2 http://herraiz.org

  3. Reaching Google Reaching Google 1 10.8.0.1 ( 10.8.0.1 ) 1 10.8.0.1 ( 10.8.0.1 ) 2 192.168.1.1 ( 192.168.1.1 ) 2 192.168.1.1 ( 192.168.1.1 ) 3 62.81.125.179.static.user.ono.com ( 62.81.125.179 ) 3 62.81.125.179.static.user.ono.com ( 62.81.125.179 ) 4 10.115.49.217 ( 10.115.49.217 ) 4 10.115.49.217 ( 10.115.49.217 ) 5 10.127.151.49 ( 10.127.151.49 ) 5 10.127.151.49 ( 10.127.151.49 ) 6 10.127.10.137 ( 10.127.10.137 ) 6 10.127.10.137 ( 10.127.10.137 ) 7 10.127.10.133 ( 10.127.10.133 ) 7 10.127.10.133 ( 10.127.10.133 ) 8 10.127.3.82 ( 10.127.3.82 ) 8 10.127.3.82 ( 10.127.3.82 ) 9 213.242.71.21 ( 213.242.71.21 ) 9 213.242.71.21 ( 213.242.71.21 ) 10 ae-5-5.ebr1.Paris1.Level3.net ( 4.69.141.42 ) 10 ae-5-5.ebr1.Paris1.Level3.net ( 4.69.141.42 ) 11 ae-45-45.ebr1.London1.Level3.net ( 4.69.143.101 ) 11 ae-45-45.ebr1.London1.Level3.net ( 4.69.143.101 ) 12 ae-1-51.edge3.London1.Level3.net ( 4.69.139.73 ) 12 ae-1-51.edge3.London1.Level3.net ( 4.69.139.73 ) 13 unknown.Level3.net ( 212.113.15.186 ) 13 unknown.Level3.net ( 212.113.15.186 ) 14 209.85.255.78 ( 209.85.255.78 ) 14 209.85.255.78 ( 209.85.255.78 ) 15 66.249.95.173 ( 66.249.95.173 ) 15 66.249.95.173 ( 66.249.95.173 ) 16 216.239.49.45 ( 216.239.49.45 ) 16 216.239.49.45 ( 216.239.49.45 ) 17 * * * 17 * * * 18 ww-in-f147.1e100.net ( 209.85.229.147 ) 18 ww-in-f147.1e100.net ( 209.85.229.147 ) 3 http://herraiz.org

  4. Reaching Google Reaching Google 1 10.8.0.1 ( 10.8.0.1 ) 1 10.8.0.1 ( 10.8.0.1 ) Getafe 2 192.168.1.1 ( 192.168.1.1 ) 2 192.168.1.1 ( 192.168.1.1 ) 3 62.81.125.179.static.user.ono.com ( 62.81.125.179 ) 3 62.81.125.179.static.user.ono.com ( 62.81.125.179 ) 4 10.115.49.217 ( 10.115.49.217 ) 4 10.115.49.217 ( 10.115.49.217 ) 5 10.127.151.49 ( 10.127.151.49 ) 5 10.127.151.49 ( 10.127.151.49 ) Barcelona 6 10.127.10.137 ( 10.127.10.137 ) 6 10.127.10.137 ( 10.127.10.137 ) 7 10.127.10.133 ( 10.127.10.133 ) 7 10.127.10.133 ( 10.127.10.133 ) 8 10.127.3.82 ( 10.127.3.82 ) 8 10.127.3.82 ( 10.127.3.82 ) Minneapolis 9 213.242.71.21 ( 213.242.71.21 ) 9 213.242.71.21 ( 213.242.71.21 ) Paris 10 ae-5-5.ebr1.Paris1.Level3.net ( 4.69.141.42 ) 10 ae-5-5.ebr1.Paris1.Level3.net ( 4.69.141.42 ) 11 ae-45-45.ebr1.London1.Level3.net ( 4.69.143.101 ) 11 ae-45-45.ebr1.London1.Level3.net ( 4.69.143.101 ) 12 ae-1-51.edge3.London1.Level3.net ( 4.69.139.73 ) 12 ae-1-51.edge3.London1.Level3.net ( 4.69.139.73 ) London 13 unknown.Level3.net ( 212.113.15.186 ) 13 unknown.Level3.net ( 212.113.15.186 ) Atlanta 14 209.85.255.78 ( 209.85.255.78 ) 14 209.85.255.78 ( 209.85.255.78 ) 15 66.249.95.173 ( 66.249.95.173 ) 15 66.249.95.173 ( 66.249.95.173 ) New York 16 216.239.49.45 ( 216.239.49.45 ) 16 216.239.49.45 ( 216.239.49.45 ) Los Angeles 17 * * * 17 * * * 18 ww-in-f147.1e100.net ( 209.85.229.147 ) 18 ww-in-f147.1e100.net ( 209.85.229.147 ) Atlanta 4 http://herraiz.org

  5. Hops while attempting to reach Hops while attempting to reach Google Google 5 http://herraiz.org

  6. Is it that bad? Is it that bad? What kind of private Information can be captured? 6 http://herraiz.org

  7. Non-cyphered information Non-cyphered information ● Geolocalization ● Using your IP address ● Web browser and operating system ● Any info written in a form ● Including passwords ● Cookies ● Have a look and take care – http://www.youtube.com/watch?v=yyLdxO6xvh8 – http://www.youtube.com/watch?v=1FgKL2ywrX0 7 http://herraiz.org

  8. Is it important? Is it important? ● Strong PK crypto illegal in France up to 2004 ● PK implementations in software considered weapons in the US ● Software export restrictions in EU and US http://en.wikipedia.org/wiki/Cryptography_law http://en.wikipedia.org/wiki/Key_disclosure_law http://en.wikipedia.org/wiki/Phil_Zimmermann 8 http://en.wikipedia.org/wiki/Export_of_cryptography_in_the_United_States#History http://herraiz.org

  9. Solution Enforce cyphering using public key cryptography 9 http://herraiz.org

  10. Cryptography Cryptography ● Traditionally, cyphering was done using a password and an algorithm ● Symmetric approach ● Password shared by both peers ● Public key cryptography ● Insecure channel ● Private and secure communication without any previous physical contact 10 http://herraiz.org

  11. Public key cryptography (PKP) Public key cryptography (PKP) Pub Pri Pub Pri 11 http://herraiz.org

  12. Public key cryptography Public key cryptography Pub Pri Pub Pri Keyserver Pub Pub 12 http://herraiz.org

  13. Criptografía de clave pública Criptografía de clave pública Hi there! Pub Pri Pub Pri Keyserver Pub Pub 13 http://herraiz.org

  14. Public key cryptography Public key cryptography Pub 0F231A5 Pub Pri Pub Pri Keyserver Pub Pub 14 http://herraiz.org

  15. Public key cryptography Public key cryptography Pub 0F231A5 Pub Pri Pub Pri Keyserver Pub Pub 15 http://herraiz.org

  16. Public key cryptography Public key cryptography Hi there! Pub Pri Pub Pri Keyserver Pub Pub 16 http://herraiz.org

  17. How does it work? How does it work? ● PKP Algorithms ● Prime number factorization ● From a mathematical point of view, all messages can be decrypted ● From a computational point of view, decrypting a message without the private key takes too long – Key length is a crucial property 17 http://herraiz.org

  18. Public key sample Public key sample -----BEGIN PGP PUBLIC KEY BLOCK----- Version: GnuPG v2.0.19 (GNU/Linux) JeP5F/eRS9G8EE1fObRRW6mRf+bGSeluFEMiOi3UB/5P0GBx8iM0QIjezR0R+2n8 bMjuJmWHTjvEeplnx9iual4J4BT/9FznFs7o4tFVVfYBacFrhWjQyAf2xoP3gyn3 5OlV55VHVB+oidXUVNSNHZbXwrd1sH42x7x8o17PDFJrWjiq4kAb2EfSOIuSS6na K9Y06bqh3yRbVtRdZOuCLcY8QJwt/mx//uQqG6NuSvYhx1QyC6g==XuDESOIuSSa mQINBEtUTeQBEACejdGQhscmsDXM7xG2/ZYFpMQg/GmPlJ85uJJUkLr2T+5Rw8Xv VfZjNZkMwsq94BGFrBxu477tKhQ5wiUBBz/jJ01a39Wrazgp21fvEon2T0Vay45t 2BYbU4AF815UL6o74YlW5SLdAofwylZS8pX4CKjGAB0T+fDiwkAepQl45nzX0ulv -----END PGP PUBLIC KEY BLOCK----- 18 http://herraiz.org

  19. Private key sample Private key sample -----BEGIN PGP PRIVATE KEY BLOCK----- Version: GnuPG v2.0.19 (GNU/Linux) mQINBEtUTeQBEACejdGQhscmsDXM7xG2/ZYFpMQg/GmPlJ85uJJUkLr2T+5Rw8Xv JeP5F/eRS9G8EE1fObRRW6mRf+bGSeluFEMiOi3UB/5P0GBx8iM0QIjezR0R+2n8 VfZjNZkMwsq94BGFrBxu477tKhQ5wiUBBz/jJ01a39Wrazgp21fvEon2T0Vay45t 2BYbU4AF815UL6o74YlW5SLdAofwylZS8pX4CKjGAB0T+fDiwkAepQl45nzX0ulv bMjuJmWHTjvEeplnx9iual4J4BT/9FznFs7o4tFVVfYBacFrhWjQyAf2xoP3gyn3 5OlV55VHVB+oidXUVNSNHZbXwrd1sH42x7x8o17PDFJrWjiq4kAb2EfSOIuSS6na K9Y06bqh3yRbVtRdZOuCLcY8QJwt/mx//uQqG6NuSvYhx1QyC6g==XuDESOIuSSa -----END PGP PRIVATE KEY BLOCK----- 19 http://herraiz.org

  20. Keyservers Keyservers ● Internet hosts that contain public keys ● Federated services ● All servers contain all the public keys in the world ● Public keyserver in Spain thanks to RedIRIS ● URL: pgp.rediris.es 20 http://herraiz.org

  21. Message signing Message signing Hi there! Pub Pri Pub Pri Keyserver Pub Pub 21 http://herraiz.org

  22. Message signing Message signing Created with the private key Hi there! Pub Pri Pub Pri Keyserver Pub Pub 22 http://herraiz.org

  23. Message signing Message signing Hi there! Pub Pri Pub Pri Keyserver Pub Pub 23 http://herraiz.org

  24. Signing and encrypting Signing and encrypting Hi there! Pub Pri Pub Pri Keyserver Pub Pub 24 http://herraiz.org

  25. Signing and encrypting Signing and encrypting Pub FAD43A Pub Pri Pub Pri Keyserver Pub Pub 25 http://herraiz.org

  26. Signing and encrypting Signing and encrypting Pub FAD43A Pub Pri Pub Pri Keyserver Pub Pub 26 http://herraiz.org

  27. Signing and encrypting Signing and encrypting Hi there! Pub Pri Pub Pri Keyserver Pub Pub 27 http://herraiz.org

  28. Signing and encrypting Signing and encrypting Hi there! Pub Pri Pub Pri Keyserver Pub Pub 28 http://herraiz.org

  29. Identity certification Identity certification How do you know that public keys belong to their legitimate owners? Can we ensure that the Public key key does belong to Barack Obama Barack Obama? 29 http://herraiz.org

  30. Identity certification Identity certification Certificate Authorities Trust chain 30 http://herraiz.org

  31. Public key signing Public key signing ● Public keys are plain text documents that can be cryptographically signed ● Mutual public signing adds identity certification to PKP schemes 31 http://herraiz.org

  32. Public key signing Public key signing Barack Obama Pub Pri Pub Pri Keyserver Pub Pub 32 http://herraiz.org

  33. Public key signing Public key signing Barack Obama Key FE0A7AF2 Name Barack Obama Fingerprint D0DA E915 BFDD E5CD 8BA0 B159 7E97 2ACB FE0A 7AF2 Pub Pri Pub Pri Keyserver Pub Pub 33 http://herraiz.org

  34. Public key signing Public key signing Barack Obama Key FE0A7AF2 Name Barack Obama Fingerprint D0DA E915 BFDD E5CD 8BA0 B159 7E97 2ACB FE0A 7AF2 Pub Pri Pub Pri Keyserver Pub Pub 34 http://herraiz.org

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