2015 Summer Cryptography Paar Introduction to Crpytography Divya Agarwal and Katie Marsh - Rhea

1. Introduction to cryptography

The block diagram below shows an overview of the field of cryptology.

Fig 1: Overview of field of Cryptology

Cryptography is the science of secret writing with the goal to hide the orginal message.

Cryptanalysis is the science and sometimes art of breaking cryptosystems.

Cryptography itself splits into three main branches:

1. Symmetric Algorithms :

• Also known as private-key, single-key or secret-key cryptography

Fig 2: Symmetric Cryptography Basics

• In Fig 2, x is the plaintext message which Alice wants to send, y is the ciphertext message which has been encrypted, K is the key to encrypt or decrypt the message.

• Encryption equation : $ y = e_k(x) $ , where $ e_k(x) $ is the encryption function

  Decryption equation : $ x = d_k(y) $  , where $ d_k(x) $ is the decryption function 

• Encryption and decryption are inverse operations if the same key K is used on both sides :

 $  d_k(y)= d_k(e_k(x))= x  $

• However, the system is only secure if an attacker does not learn the key K!

2.

Text of first section goes here. Here is an example of an equation. $ f(x)= \frac{1}{5} \sin x \int_{-\infty}^\alpha \pi^y dy $

2. Derivation (Replace by appropriate section title)

Text of second section goes here. Here is an example of a list

• Blah
• Blih
• Bloh
  • Blouh

4. Conclusion (Replace by appropriate section title)

Text of fourth section goes here.

5. References

• C. Paar. Understanding Cryptography. Lecture Notes. Dept. of Electr. Eng. and In­for­ma­ti­on Sci­en­ces, Ruhr University.
• C. Paar and J. Pelzl. Understanding Cryptography. A textbook for Student and Practitioners. Springer 2010.

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