Cripto-Códigos Matemáticas para resguardo de información. Ken Bauer Associate Professor of Computing Tecnológico de Monterrey in Guadalajara

2 Key Terms today ● Cryptography and Cryptanalysis ● Cipher (cryptographic algorithm), key ● Plaintext and Ciphertext ● Symmetric vs. Asymmetric Encryption ● Conventional (Simple) Cryptography ● Public key Cryptography ● Digital Certificates ● Levels of Trust

3 Bruce Schneier Bruce Schneier, Applied Cryptography: Protocols, Algorithms, and SourceCode in C. “There are two kinds of cryptography in this world: cryptography that will stop your kid sister from reading your files, and cryptography that will stop major governments from reading your files. This book is about the latter.”

4 Encryption and Decryption (symmetric) Source: http://www.ncsa.illinois.edu/People/ncsairst/pgp/IntroToCrypto.pdf

5 Encryption and Decryption (Asymmetric) Source: http://www.ncsa.illinois.edu/People/ncsairst/pgp/IntroToCrypto.pdf

6 Caesar Cipher Source: https://www.instructables.com/id/Basics-of-Cryptography-Caesar-Cipher/

7 Caesar’s Cipher Exercises 1) Cipher with shift +3: Hola Javier 2) Cipher with shift +12: Me gusta mucho pizza 3) Decode with shift +5: ltytufwnx 4) Decode with shift +21: adiyevhznwjiy 5) Caesar cipher using frequency analysis: espntaspcsldmppymczvpy 6) Caesar cipher using frequency analysis: kgyezuhxkgq

8 Privacy and Security https://youtu.be/XY5l8NHaGEI

9 More Tools 1) Create your Keybase account. 2) Validate your Keybase account. 3) Send an encrypted message to Ken via Keybase.

10 Bibliography ● “An Introduction to Cryptography”, Network Associates, Inc., 1998: http://www.ncsa.illinois.edu/People/ncsairst/pgp/IntroToCrypto.pdf ● “Basics of Cryptography: Caesar Cipher”, https://www.instructables.com/id/Basics-of-Cryptography-Caesar-Cipher/ ● “Caesar Ciphers: An Introduction to Cryptography”, Purdue University, 2006/2007, https://gencyber.utulsa.edu/wp-content/uploads/2016/10/Ceasar-Ciphers-An-Introduction-to-Cryptography-lesson-plan-for-math.pdf

11 References ● Slides at: https://speakerdeck.com/kenwbauer ● “Yet Another Introductory Number Theory Textbook”, Jonathan A. Poritz: https://poritz.net/jonathan/share/yaintt.pdf ● Privacy Tools: https://www.privacytools.io/ ● EFF Privacy: https://www.eff.org/issues/privacy ● Bruce Schneier: https://www.schneier.com/ ● Brian Krebs: https://krebsonsecurity.com/ ●