الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
 |  | from | 187 |  |  |
| | | from | 187 | | |
Abstract
After the study of DES algorithm’s and performance , one can notice that ; the histogram of the original text has a limited bandwidth with peaks at certain few locations, while the encrypted text has a wide spectrum histogram with nearly peaks at many points which leads to that: DES is not a monoalphabetic coding scheme and its resulting code does not imply any indication of the original text.
Viewing the 100 random text where root mean-square difference (Euclidean distance) between the original text and the coded are, it can be observed that the RJV1S distance does not obey any law which mean an intruder can not recognize the coding scheme given some source code pairs
Based upon the analysis of the simulation experiments of IDEA algorithm , the following conclusion can be driven: While the original histogram is band limited and has few peaks, the coded text’s histogram has a normal (Gaussian distribution) however it does not indicate how the code is formed. After 100 experiments on the IDEA algorithm measuring RMS distance (Euclidean distance) it can not be traced by any analytical form. Hence, it enhances security properties.
In Message Digest MD2 After 40 experiments performed on a pair of [text statements, the following measurement took place: For each pair of the riginal text messages, the hamming distance (Euclidean distance) or RMS ifference between them is measured. For the corresponding pairs of coded ;ssages, the same distance is measured between them.