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Online\OfflineData Encryption and
Decryption Process
using Bit OperationsPresented By:
Rakshith R NaikUnder the Guidance of:
Prof. M. V. Jerabandi (M.tech, CSE)
CONTENTS
IntroductionRelated workMethodologyAlgorithmProcess In MemoryAnalysisDemoConclusion
ENCODING?DECODING?PUBLIC KEY?COMPRESSION?WHY ENCRYPTION?WHY DECRYPTION?WHY COMPRESSION?
INTRODUCTION
WikipediaB. Ravi Kumar. et. alB. Ravi Kumar. et. alJ. Freeman. et. alWayne G. Barker. et. alN. A Kofahi. et. alW. Stallings. et. al
X. Lai. et. alDiffie. et. alC.P. Wu. et. alM . J. Weiner. et. al
RELATED WORK
Encryption process
In this process every eight bytes of plain text becomes seven bytes of cipher text.
METHODOLOGY
Input: Text file, keyOutput: Encrypted file
Repeat for every 8 characters of input fileFor each i from 7 to 1
Take ith bit from 8th character Replace it in the ith character at 8th bit position Write the character to temporary file
Repeat for every character of the temporary file XOR key with character Write the character to encrypted file
ENCRYPTION ALGORITHM
ENCRYPTION IN MEMORY CELL
EXAMPLECharacter ASCII
ValueBinary Number
a 65 0 1 0 0 0 0 0 1
b 66 0 1 0 0 0 0 1 0
c 67 0 1 0 0 0 0 1 1
d 68 0 1 0 0 0 1 0 0
e 69 0 1 0 0 0 1 0 1
f 70 0 1 0 0 0 1 1 0
g 71 0 1 0 0 0 1 1 1
h 72
Bit Positions 8 7 6 5 4 3 2 1
Before Encryption: abcdefgh
Character Binary Number
a 1 0 0 0 0 0 1
b 1 0 0 0 0 1 0
c 1 0 0 0 0 1 1
d 1 0 0 0 1 0 0
e 1 0 0 0 1 0 1
f 1 0 0 0 1 1 0
g 1 0 0 0 1 1 1
Bit Positions
8 7 6 5 4 3 2 1
After Encrypted :
10 0 00 010
ENCRYPTION RESULT
Decryption Process
In this process for every 7 characters of cipher text the 8 characters of original text will appears.
DECRYPTION
DECRYPTION ALGORITHM
Input: Encrypted file, keyOutput: Decrypted file
Repeat for every characters of encrypted file XOR key with character Write the character to temporary file
Repeat for every 7 character of the temporary fileFor each I from 7 to 1
Take 8th bit from ith character Place it in the ith bit of 8th character Write the character to decrypted file
DECRYPTION IN MEMORY CELL
EXAMPLE
Character Binary Number
a 0 1 0 0 0 0 0 1
b 0 1 0 0 0 0 1 0
c 0 1 0 0 0 0 1 1
d 0 1 0 0 0 1 0 0
e 0 1 0 0 0 1 0 1
f 0 1 0 0 0 1 1 0
g 0 1 0 0 0 1 1 1
h
Bit Positions
8 7 6 5 4 3 2 1
Character Binary Number
a 1 0 0 0 0 0 1
b 1 0 0 0 0 1 0
c 1 0 0 0 0 1 1
d 1 0 0 0 1 0 0
e 1 0 0 0 1 0 1f 1 0 0 0 1 1 0
g 1 0 0 0 1 1 1
Bit Positions
8 7 6 5 4 3 2 1
Before Decryption :
After Decryption : abcdefgh
0
0
1001
0
0
DECRYPTION RESULT
METHODOLOGY
Data CompressionThe purpose of data compression is that we can reduce the size of data to save storage and reduce time for transmission.
In this process Data is compressed by using Huffman coding.
HUFFMAN CODING
Huffman code process
Huffman code is particular type of optimal prefix code that is commonly used for data compression
The process of huffman code is converting the characters into binary form based on their frequencies in a plain text and optimum or compress the text length.
HUFFMAN CODING ALGORITHMInput: Encrypted fileOutput: Compressed file
1. Find the frequency of each character2. Group the character according to frequency and
label it as node3. Merge the two smallest probabilities into its parent
node4. Repeat the 2nd step until a super symbol remains
EXAMPLE
Let A={a/20, b/17, c/3, d/15, e/45} be the alphabet and its frequency distribution
a=20
b=17
c=3
d=15
e=45
The Huffman code is A=00, b=010, c=0110, d=0111, e=1
12
3
4
DEMO
ANALYSIS
An implementation of BSS encryption algorithm is presented.
The algorithm is simple to implement, effective, and easy to understand.
It performs well and works efficiently with text file of any size.
The results obtained are presented. It provides both security and data compression.
This can be extended to images, audio & video files.
CONCLUSION & FUTURE WORK
[1] Wikipedia, “Encryption”, http://en.wikipedia.org/wiki/Encryption, modified on 13 December 2006.
[2] B. Ravi Kumar, Dr. P. R. K.Murti B. Ravi Kumar et al. / International Journal on
Computer Science and Engineering (IJCSE) [3] J. Freeman, R. Neely, and L. Megalo “Developing
Secure Systems: Issues and Solutions”. IEEE Journal of Computer and Communication, Vol. 89, PP. 36-45. 1998
REFERENCES
THANK YOU
QUESTIONS ????????