Cryptology Tim Cahill Ryan Church

Cryptology Cryptology - the science and study of cryptanalysis and cryptography. Cryptography - the procedures, processes, methods, etc., of making and using secret writing, as codes or ciphers. Ex: The process where you take your message and encode it using a key you make up. your sentence = yana is awesome your key = +3 Encoded message = bdqd lv dzhvrph Cryptanalysis - the procedures, processes, methods, etc., used to translate or interpret secret writings, as codes and ciphers, for which the key is unknown. Ex: encrypted segment = DEF cryptanalysis is the process where you go from the encrypted segment “DEF” to the decrypted segment “ABC” without using the key.

Terms (cont.) Public key = in cryptography, a value associated with a particular person and used to decrypt messages from that person or encrypt messages to him/her. Ex: key can be anything you make up, it could be as simple as encryption = letter +3, or more complicated like encryption = letter +3 -2 *3 /2. PROJECT PROGRESS Main project is a hill cipher. Which is a more complicated cipher which involves a two by two matrix.

Programming Example Caesar cipher: #include<stdio.h> #define SIZE 10 int main(){   int i=0;   char z, x[SIZE], c[SIZE]={0};   printf("Enter a 10 character message:  ");   while(i<10){     c[i]=getchar();     i++;   }   i=0;     while(i<10){     x[i]=c[i]+3;     printf("%c", x[i]);     i++;   } printf("\n\n");   i=0;   while(i<10){       z=x[i]-3;       i++;       printf("%c", z);     }         printf("\n");   return 0; }

Quiz 1) What is the difference between cryptology and cryptography? 2) What is the main use for cryptology? 3) Draw how public key is used. 4) What would the encoded message of Yana be if the key is +4?

References Spam and the ongoing battle for the inbox. Communications of the ACM, Volume 50, #2 (2007), pages 24-33. Joshua Goodman, Gordon V. Cormack, David Heckerman. Textbook: Invitation to computer science java version Edition 3, Schneider, copyright 07. pages 600-607 An overview of cryptography. Gary C. Kessler, may 1998 (23 January 2009). (website) www.garykessler.net/library/crypto.html#purpose