Project: 01- Encrypted Data Transfer

Our project deals with the demonstration of modern days’ technology of transmitting

data through high security encryption in commercial and military use. We have used a

very simple system of Transmitter and receiver module and chipper software for the

project. This project gives an outline to a layman about how the modern systems

handles and secures electronic data transfers.

HISTORY, DEVELOPMENT & APPLICATIONS -

Cryptography has a long and fascinating history. The most complete non-technical

account

of the subject is Kahn’s The Codebreakers. This book traces cryptography from its

initial and limited use by the Egyptians some 4000 years ago, to the twentieth century

where it played a crucial role in the outcome of both world wars. Completed in 1963,

Kahn’s book covers those aspects of the history which were most significant (up to that

time) to the developmentof the subject. The predominant practitioners of the art were

those associated with the military, the diplomatic service and government in general.

Cryptography was used as a tool to protect national secrets and strategies.

The proliferation of computers and communications systems in the 1960s brought with

it a demand from the private sector for means to protect information in digital form

and to provide security services. Beginning with the work of Feistel at IBMin the early

1970s and culminating in 1977 with the adoption as a U.S. Federal Information

Processing Standard for encrypting unclassified information, DES, the Data Encryption

Standard, is the most well-known cryptographic mechanism in history. It remains the

standard means for securing electronic commerce for many financial institutions

around the world.

In 1978 Rivest, Shamir, and Adleman discovered the first practical public-key

encryption and signature scheme, now referred to as RSA. The RSA scheme is based

on another hard mathematical problem, the intractability of factoring large integers.

This application of a hard mathematical problem to cryptography revitalized efforts

to find more efficient methods to factor. The 1980s saw major advances in this area

but nonewhich rendered the RSA systeminsecure. Another class of powerful and

practical public-key schemes was found by ElGamal in 1985. These are also based on

the discrete logarithm problem.

One of the most significant contributions provided by public-key cryptography is the

digital signature. In 1991 the first international standard for digital signatures (ISO/IEC

9796) was adopted. It is based on the RSA public-key scheme. In 1994 the U.S.

Government

adopted the Digital Signature Standard, a mechanism based on the ElGamal publickey

scheme. The search for new public-key schemes, improvements to existing

cryptographicmechanisms, and proofs of security continues at a rapid pace. Various

standards and infrastructures involving cryptography are being put in place. Security

products are being developed

to address the security needs of an information intensive society.

The way information is recorded has not changed dramatically over time.

Whereas information was typically stored and transmitted on paper, much of it now

resides on magnetic media and is transmitted via telecommunications systems, some

wireless.

What has changed dramatically is the ability to copy and alter information. One can

make thousands of identical copies of a piece of information stored electronically and

each is indistinguishable from the original. With information on paper, this is much

more difficult.

SCADA (Supervisory Control And Data Acquisition) is a system for remote

monitoring and control that operates with coded signals over communication channels

(using typically one communication channel per remote station). The control system

may be combined with a data acquisition system by adding the use of coded signals

over communication channels to acquire information about the status of the remote

equipment for display or for recording functions.[1] It is a type of industrial control

system (ICS). Industrial control systems are computer-based systems that monitor and

control industrial processes that exist in the physical world. SCADA systems historically

distinguish themselves from other ICS systems by being large-scale processes that can

include multiple sites, and large distances.[2] These processes include industrial,

infrastructure, and facility-based processes, as described below:

Industrial processes include those of manufacturing, production, power

generation, fabrication, and refining, and may run in continuous, batch, repetitive,

or discrete modes.

Infrastructure processes may be public or private, and include water treatment and

distribution, wastewater collection and treatment, oil and gas pipelines, electrical

power transmission and distribution, wind farms, civil defense siren systems, and

large communication systems.

Facility processes occur both in public facilities and private ones, including

buildings, airports, ships, and space stations. They monitor and control heating,

ventilation, and air conditioning systems (HVAC), access, and energy consumption.

What is needed then for a society where information is mostly stored and transmitted

in electronic form is a means to ensure information security which is independent of

the physical medium recording or conveying it and such that the objectives of

information security rely solely on digital information itself.

Project details

This project has two parts; they are the Software part and the Hardware part. While the

software part is used for encrypting the message to be sent in the transmitter side and

decrypting it in the receiver side of the system, the hardware part is there for

transmitting and receiving the message using the Morse code. In today’s world though

Morse has almost no significance but the easiest way to transmit data in this simple

model can only be done using the code. We have slightly modified it according to our

use as we will be having LEDs for the data transmission so the ‘Dot’ in is the blinking of

the ‘Red’ LED and the ‘Dash’ is the blinking of the ‘Yellow’ LED. As we can transmit 4

bits of data simultaneously, we can use four LEDs for different purpose.

Software-

We have used two softwares for the encoding and decoding purpose which will be used

in series with each other. First we will put the message in the first software and then the

encoded data will be put into the second software. The result of it will be transmitted

and will be decoded similarly using the same software in the receiving side. The

softwares with .exe extension is available with this pdf.

Hardware-

Description This radio frequency (RF) transmission system employs Amplitude Shift

Keying (ASK) with transmitter/receiver (Tx/Rx) pair operating at 434 MHz. The

transmitter module takes serial input and transmits these signals through RF. The

transmitted signals are received by the receiver module placed away from the source of

transmission.

The system allows one way communication between two nodes, namely, transmission

and reception. The RF module has been used in conjunction with a set of four channel

encoder/decoder ICs. Here HT12E & HT12D have been used as encoder and

decoder respectively. The encoder converts the parallel inputs (from the remote

switches) into serial set of signals. These signals are serially transferred through RF to

the reception point. The decoder is used after the RF receiver to decode the serial

format and retrieve the original signals as outputs. These outputs can be observed on

corresponding LEDs.

Encoder IC (HT12E) receives parallel data in the form of address bits and control bits.

The control signals from remote switches along with 8 address bits constitute a set of 12

parallel signals. The encoder HT12E encodes these parallel signals into serial bits.

Transmission is enabled by providing ground to pin14 which is active low. The control

signals are given at pins 10-13 of HT12E. The serial data is fed to the RF transmitter

through pin17 of HT12E.

Transmitter, upon receiving serial data from encoder IC (HT12E), transmits it

wirelessly to the RF receiver. The receiver, upon receiving these signals, sends them to

the decoder IC (HT12D) through pin2. The serial data is received at the data pin

(DIN, pin14) of HT12D. The decoder then retrieves the original parallel format from

the received serial data.

When no signal is received at data pin of HT12D, it remains in standby mode and

consumes very less current (less than 1μA) for a voltage of 5V. When signal is received

by receiver, it is given to DIN pin (pin14) of HT12D. On reception of signal, oscillator

of HT12D gets activated. IC HT12D then decodes the serial data and checks the

address bits three times. If these bits match with the local address pins (pins 1-8) of

HT12D, then it puts the data bits on its data pins (pins 10-13) and makes the VT pin

high. An LED is connected to VT pin (pin17) of the decoder. This LED works as an

indicator to indicate a valid transmission. The corresponding output is thus generated at

the data pins of decoder IC. A signal is sent by lowering any or all the pins 10-13 of

HT12E and corresponding signal is received at receiver’s end (at HT12D). Address

bits are configured by using the by using the first 8 pins of both encoder and decoder

ICs. To send a particular signal, address bits must be same at encoder and decoder

ICs. By configuring the address bits properly, a single RF transmitter can also be used

to control different RF receivers of same frequency.

To summarize, on each transmission, 12 bits of data is transmitted consisting of 8

address bits and 4 data bits. The signal is received at receiver’s end which is then fed

into decoder IC. If address bits get matched, decoder converts it into parallel data and

the corresponding data bits get lowered which could be then used to drive the LEDs.

The outputs from this system can either be used in negative logic or NOT gates (like

74LS04) can be incorporated at data pins.

COMPONENTS USED

1. HT12D DECODER

HT12D IC comes from HolTek Company. HT12D is a decoder integrated circuit that

belongs to 212 series of decoders. This series of decoders are mainly used for remote

control system applications, like burglar alarm, car door controller, security system etc.

It is mainly provided to interface RF and infrared circuits. They are paired with 212

series of encoders. The chosen pair of encoder/decoder should have same number of

addresses and data format. In simple terms, HT12D converts the serial input into

parallel outputs. It decodes the serial addresses and data received by, say, an RF

receiver, into parallel data and sends them to output data pins. The serial input data is

compared with the local addresses three times continuously. The input data code is

decoded when no error or unmatched codes are found. A valid transmission in

indicated by a high signal at VT pin. HT12D is capable of decoding 12 bits, of which 8

are address bits and 4 are data bits. The data on 4 bit latch type output pins remain

unchanged until new is received.

Pin Diagram

Pin Description

Pin Number

Function

Name

1 8 BIT ADDRESS PINS

FOR INPUT

A0

2 A1

3 A2

4 A3

5 A4

6 A5

7 A6

8 A7

9 GROUND (0V) GROUND

10 4 BIT DATA/ADDRESS

PINS FOR OUTPUT

D0

11 D1

12 D2

13 D3

14 SERIAL DATA INPUT INPUT

15 OSCILLATOR OUTPUT OSC 2

16 OSCILLATOR INPUT OSC 1

17 VALID

TRANSMISSION,

ACTIVE HIGH

VT

18 SUPPLY VOLTAGE; 5V

(2.4 – 12V)

Vcc

2. HT12E ENCODER

HT12E is an encoder integrated circuit of 212 series of encoders. They are paired with

212 series of decoders for use in remote control system applications. It is mainly used in

interfacing RF and infrared circuits. The chosen pair of encoder/decoder should have

same number of addresses and data format. Simply put, HT12E converts the parallel

inputs into serial output. It encodes the 12 bit parallel data into serial for transmission

through an RF transmitter. These 12 bits are divided into 8 address bits and 4 data bits.

HT12E has a transmission enable pin which is active low. When a trigger signal is

received on TE pin, the programmed addresses/data are transmitted together with the

header bits via an RF or an infrared transmission medium. HT12E begins a 4-word

transmission cycle upon receipt of a transmission enable. This cycle is repeated as long as

TE is kept low. As soon as TE returns to high, the encoder output completes its final cycle

and then stops.

Pin Diagram

Pin Description

Pin Number

Function

Name

1 8 BIT ADDRESS PINS

FOR INPUT

A0

2 A1

3 A2

4 A3

5 A4

6 A5

7 A6

8 A7

9 GROUND (0V) GROUND

10 4 BIT DATA/ADDRESS

PINS FOR INPUT

D0

11 D1

12 D2

13 D3

14 TRANSMISSION

ENABLE (ACTIVE

LOW)

TE

15 OSCILLATOR

OUTPUT

OSC 2

16 OSCILLATOR INPUT OSC 1

17 VALID

TRANSMISSION,

ACTIVE HIGH

VT

18 SUPPLY VOLTAGE;

5V (2.4 – 12V)

Vcc

3. RF MODULES (434MHz)

The RF module, as the name suggests, operates at Radio Frequency. The

corresponding frequency range varies between 30 kHz & 300 GHz. In this RF system,

the digital data is represented as variations in the amplitude of carrier wave. This kind

of modulation is known as Amplitude Shift Keying (ASK). Transmission through RF

is better than IR (infrared) because of many reasons. Firstly, signals through RF can

travel through larger distances making it suitable for long range applications. Also,

while IR mostly operates in line-of-sight mode, RF signals can travel even when there

is an obstruction between transmitter & receiver. Next, RF transmission is more

strong and reliable than IR transmission. RF communication uses a specific frequency

unlike IR signals which are affected by other IR emitting sources. This RF module

comprises of an RF Transmitter and an RF Receiver. The transmitter/receiver

(Tx/Rx) pair operates at a frequency of 434 MHz. An RF transmitter receives serial

data and transmits it wirelessly through RF through its antenna connected at pin4. The

transmission occurs at the rate of 1Kbps - 10Kbps.The transmitted data is received by

an RF receiver operating at the same frequency as that of the transmitter.

The RF module is often used along with a pair of encoder/decoder. The encoder is

used for encoding parallel data for transmission feed while reception is decoded by a

decoder. HT12E-HT12D, HT640-HT648, etc. are some commonly used

encoder/decoder pair ICs.

Pin Diagram

Receiver Module

Transmitter Module

Transmitter

Module

Pin Number

Function

Name 1 Ground (0V) GND

2 Serial Data Input Pin DATA

3 Supply Voltage (5V) VCC

4 Antenna Output Pin ANT

Receiver Module

Pin Number

Function

Name

1 Ground (0V) GND

2 Serial Data Output

Pin

DATA

3 Linear Output Pin;

Not Connected

NC

4 Supply Voltage (5V) VCC

5 Supply Voltage (5V) VCC

6 Ground (0V) GND

7 Ground (0V) GND

8 Antenna Input Pin ANT

Stills-

THANK YOU

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