8/7/2019 swdc ppt

1/25

1Gec, Bharuch

8/7/2019 swdc ppt

2/25

2Gec, Bharuch

8/7/2019 swdc ppt

3/25

INTRODUCTIONy The project SECURED WIRELESS DATA COMMUNICATION

means transmitting data between different locations, without any physicalwire connections, using the concept of cryptography.

y The word CRYPTOGRAPHY refers to the science of secretcommunication. It is a methodology for transforming the representation of message through a position-scrambling process through some method of transformation of letters or characters without changing its informationcontent.

y The original message is called plaintext or clear text and the transformed

message is called cipher text, which is also called a cryptogram. Theplaintext is transformed into cipher text by the process called Encryption. Inour project, the microcontroller does the function of encryption anddecryption process in two methods. The user has the choice of selecting anyone method of encryption

3Gec, Bharuch

8/7/2019 swdc ppt

4/25

CRYPTOGRAPHY

y Cryptography, which comes from the Greek wordskryptos or hidden and graphein or to write , is the

science of secret communication. In our project, we haveillustrated this concept of cryptography by way of establishing a simple serial communication betweenmicrocontrollers.

y

In cryptography, the process of changing plaintext tocipher text is called enciphering or encryption. Theinverse operation that changes cipher text to plaintext isknown as deciphering or decryption.

4Gec, Bharuch

8/7/2019 swdc ppt

5/25

CLASSIFICATION OF CRYPTOGRAPHY

CRYPTOGRAPHY

Conventional Key

Cryptography

Character LevelEncryption

Substitutionmethod

Monoalphabeticsubstitution

Polyalphabeticsubstitution

Transpositionmethod

Bit levelEncryption

Public Key Cryptography

5Gec, Bharuch

8/7/2019 swdc ppt

6/25

Monoalphabetic Su bstit u tiony This method is sometimes called the Caesar cipher,

each character is replaced by another character in the

set.y The monoalphabetic encryption algorithm simply

adds a number to the ASCII code of the character; thedecryption algorithm is the reverse of the encryption

operation i.e., the decryption algorithm simply subtracts the same number from the ASCII code.

6Gec, Bharuch

8/7/2019 swdc ppt

7/25

Monoalphabetic su bstit u tion-

based ciphersy Monoalphabetic substitution-based ciphers replace a

character or characters with a different character or

characters, based upon some key.y R eplacing: abcdefghijklmnopqrstuvwxyzy W ith the key: POIUYTREWQLKJHGFDSAMNBVCXZ

y The message: how about lunch at noony encodes into EGVPO GNMKN HIEPM HGGH

7Gec, Bharuch

8/7/2019 swdc ppt

8/25

Polyalphabetic

Substit

ution

y In polyalphabetic substitution, each occurrence of acharacter can have a different substitute. Onepolyalphabetic encryption technique is to find theposition of the character in the text and use that valueas the key.

y Here the key is defined as take the position of thecharacter in the text, and this position be the shifted

value .

8Gec, Bharuch

8/7/2019 swdc ppt

9/25

P olyalphabetic su bstit u tion-based

ciphersy Similar to monoalphabetic ciphers except multiple

alphabetic strings are used to encode the plaintext.y For example, a matrix of strings, 26 rows by 26

characters or columns can be used.y A key such as COMPU TER SCIENCE is placed

repeatedly over the plaintext.y COMPUTERSCIENCECOMPUTERSCIENCECOMPUTER

y thisclassondatacommunicationsisthebest

9Gec, Bharuch

8/7/2019 swdc ppt

10/25

P olyalphabetic su bstit u tion-based ciphers

To encode the message, take the first letter of theplaintext, and the corresponding key characterimmediately above it, C. Go to row C column t in the26x26 matrix and retrieve the cipher text character V.

y Continue with the other characters in the plaintext.

10Gec, Bharuch

8/7/2019 swdc ppt

11/25

Gec, Bharuch 11 1111

PlaintextMessage

EncodedMessage

PlaintextMessage

encrypt decrypt

identical keys

TransmittedMessage

Sender R eceiver

Same key for encryption and decryption.How is key shared?

SYMMETRIC ENCRYPTION METHOD

8/7/2019 swdc ppt

12/25

B LOCK DIAGRA M

KEYBOARD

M ICRO

CON TROLLER AM TRANSM ITTER

LCD D ISPLAY

AM RE CE IVERM ICRO

CON TROLLER LCD D ISPLAY

TRANSMITTER BLOCK DIAGRAM

RECEIVER BLOCK DIAGRAM 12Gec, Bharuch

8/7/2019 swdc ppt

13/25

B LOCK DIAGRA M EXPLANATIONy The data to be transmitted is given to the keyboard which

converts scan codes into ASCII codes. In microcontroller theASCII codes are encrypted using substitution algorithm. Theinput data will be displayed in LCD.

y The encrypted data gets combined with address bits in encoderand are transmitted to receiver by transmitter module using anantenna.

y The receiver module receives the transmitted data and thedecoder separates the address and data bits. If the addresses arematched the data bits are decrypted in the microcontroller andthe original data gets displayed in LCD.

13Gec, Bharuch

8/7/2019 swdc ppt

14/25

TRANSM

ITTER CIRCUIT DIAGRAM

CIRCUIT DIAGRAM OF TRANSMITTER 14Gec, Bharuch

8/7/2019 swdc ppt

15/25

RECEIVER CIRCUIT DIAGRAM

CIRCUIT DIAGRAM OF RECEIVER 15Gec, Bharuch

8/7/2019 swdc ppt

16/25

CIRCUIT DIAGRA M EXPLANATIONy The Circuit consists of the Message transmitter and a

R eceiver section. The transmitter section has amicrocontroller which gets the text message from thekeyboard. This text message was encrypted by the specifiedalgorithm and the encrypted data was transmittedcontinuously through the FM transmitter.

y At the receiving end the FM signal was received by the FMreceiver and the data was fed to the microcontroller andthe microcontroller will decrypt by the specified algorithmand the decrypted data was displayed it over the LCDdisplay.

16Gec, Bharuch

8/7/2019 swdc ppt

17/25

START

CONVERT SCAN CODE TO ASCII

GET APPROPRIATEALGORITHM FROM USER

SEND DATA

ADD KEY TO

EACH CHARACTER

CHECK FOR MONOALPHABETIC

GET KEY FROM USERGET KEY FROM USER

ADD KEY TOFIRST CHARACTER

NO YES

YES

NOCHECK EDIT

BUTTONPRESSED

GET DATA FROM KEYBOARD

DISPLAY ON LCD

CHECK SENDBUTTON

PRESSED

INCREMENT AND ADD

KEY BASED ON POSITIONOF CHARACTER

ALL DATA

SEND

NO

YES

NO

YES TRANSMITTER FLOW CHART17Gec, Bharuch

8/7/2019 swdc ppt

18/25

START

STORE IT IN MEMORY

SWITCH ON BUZZER FOR2 SECONDS

GET APPROPRIATEALGORITHM FROM USER

DISPLAY IT ON LCD

SUBTRACT KEY FROMEACH CHARACTER

CHECK FOR

START BITRECEIVED

CHECK FOR MONOALPHABETIC

GET KEY FROM USERGET KEY FROM USER

SUBTRACT KEY FROMFIRST CHARACTER

INCREMENT AND SUBTRACTKEY BASED ON POSITION

OF CHARACTER

GET DATA LENGTH

GET DATA ACCORDING TO LENGTH

NO YE S

YES

NO

RECEIVER FLOW CHART18Gec, Bharuch

8/7/2019 swdc ppt

19/25

ADVANTAGES

y As we are using microcontroller,y There is less heat dissipation problem.y It has built-in heat dissipater.

y Microcontroller chip is readily available and also atcheap cost.

19Gec, Bharuch

8/7/2019 swdc ppt

20/25

DISADVANTAGE & LIM

ITATION

y This project limits range of wireless datacommunication is 100 feet that depends on R F

modules because R F modules used in this projectworks in this range.

20Gec, Bharuch

8/7/2019 swdc ppt

21/25

APPLICATIONS

y This concept of cryptography is used in military levelcommunication to maintain secrecy of communication.

21Gec, Bharuch

8/7/2019 swdc ppt

22/25

CONCLUSION

This project depicts us a clear view aboutcryptographic concept in wireless data communication. By implementing this system the communications is madebetter & fast. Thus we can able to send Text messagethrough R F with the help of Microcontroller.

Here Microcontroller plays an important role; it is theheart of this technology. It is more useful in military,education, business, hospitals etc. Number of character

sent can be get increased (by connecting an externalmemory) and message transmission to cell or vice versa ispossible in Future development of this Project. So it isuser-friendly in function and easy, cheap to implement.

22Gec, Bharuch

8/7/2019 swdc ppt

23/25

SCOPE FOR FUTURE

y The number of characters transmitted at a time is 6 4in our project, which can be increased by addingexternal R AM with the microcontroller.

y The transmitting distance can be increased by increasing the power of the transmitter & R eceiver.

y The LCD display in our project is 16x 2, so that it candisplay maximum characters of 6 4 on it. This can alsobe increased more.

y Picture messages can also transmitted by using agraphic display.

23Gec, Bharuch

8/7/2019 swdc ppt

24/25

REFERENCESTEX TS:

y Electronics for you (February 2001)y Electronics for you (April 2001)y Electronics for you (February 2003)y Gokhale Introduction to telecommunicationsy Hill Associated TELECOMMUNICA TION - A beginners guidey Kenneth.J.Ayala (Second edition). The 80 51 Microcontroller Architecture,

programming and applications .y Muhammad Ali Mazidi , Janice Gillispie Mazidi.( 2002) -THE 8051

MICR OCONTR OLLER AND EMBEDDED SYSTEMSW ebsites:

y www.80 52.comy www.atmel .comy www.hitachi.comy www.nationalsemiconductor.comy www.dalsemi.comy www.microcontroller.net

24Gec, Bharuch

8/7/2019 swdc ppt

25/25

25Gec, Bharuch