Playfair Cipher
1.not even the Large number of keys in a monoalphabetic cipher provides security
2.one approach to improving security was to encrypt multiple letters
3.the Playfair Cipher is an example
4.invented by Charles Wheatstone in 1854,but named after his friend Baron Playfair
Playfair Key Matrix
1.a 5X5 matrix of letters based on a keyword
2.fill in letters of keyword (sans duplicates)
3.fill rest of matrix with other letters
Encrypting and Decrypting
-plaintext is encrypted two letters at a time
1. if a pair is a repeated letter, insert filler like X’
2. if both letters fall in the same row, replace each with letter to right (wrapping back to start from end)
3. if both letters fall in the same column, replace each with the letter below it (again wrapping to top from
bottom)
4. otherwise each letter is replaced by the letter in the same row and in the column of the other letter of the pair
This is a simple algorithm that downloads trading data from yahoo database. It is basically a Large scale application of sqq.m which was originally submitted by Michael Boldin, link at acknowledgements.
Some of the functionalities of the package:
- User defined ticker list.
- Function for downloading most recent SP500 composition in ticker list.
- Control for bad data (e.g. a certain percentage of prices missing).
- Choice of frequency of data (e.g. weekly prices).
- Choice of starting and ending data.
- Function for saving the whole data in a pre-formatted excel file together with a full reports on missing data.
RX Library contains a Large number of components, objects and routines for Borland Delphi with full source code. This library is compatible with Borland Delphi 1, 2, 3, 4 and Borland C++ Builder 1 and 3.
