Java Network programs

8/14/2019 Java Network programs

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EX: NO: 1 IP ADDRESS OF LOCAL HOST

AIM:

To write a java program to find the IP address of the system.

ALGORITHM:

STEP1:Start

STEP:Declare a variable ip as a static InetAddress

STEP!:Using a function get ocal!ost "# to find the address of the s$stem.

STEP":Using the function get!ost%ame"# find the s$stem no and print it.

STEP#:Using the function get&$%ame"# find the name of an$ other s$stem.

STEP$:Displa$ the name

STEP%:Stop


2/91

PROGRAM:

import java.io.'(

import java.net.'(class Address

)public InetAddress ip(

public static void main"String arg*+#throws Un,nown!ost-ception)

InetAddress ip/InetAddress.getocal!ost"#(

S$stem.out.println"01n Ip address is 203ip#(String si/ip.get!ost%ame"#(

S$stem.out.println/"01n S$stem number is203si#(

InetAddress ip4/InetAddress.get&$%ame"0s$s 450#(S$stem.out.println"01n %ame of the other s$stem is203ip#(

6

6


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O&TP&T:

-217cn1javac Address.java

-217cn1java Address

Ip address is2 s$s8894:8.4;


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EX: NO: &DP' ONE (A) COMM&NICATION

AIM:

To write a java program to implement o*e +ay ,omm-*.,at.o* -s.*/ &DP0

ALGORITHM:

SENDER:'

STEP1:Import the net pac,age and other pac,ages.

STEP:String of argument is passed to the args *+.

STEP!:=reate a Datagram soc,et and bind it to the special port specified.

STEP":>et the buffer si?e and I@ Address of local host and communication with

the client.

STEP#:Send the Datagram pac,et to the destination address of given port.

STEP$:Store the input in the buffer at the specific location.

RECEIER:'




STEP":=reate pac,et for receving arra$ of b$tes with maimum b$tes.

STEP#:Specif$ the common port for connecting datagram soc,et.


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PROGRAM:

SENDER:'

import java.io.'(

import java.net.'(

class Sender)

DatagramSoc,et ds(

Datagram@ac,et dp(b$te buff*+/new b$te*458+(

String strBstr4(

boolean i/true(public void send"# throws IC-ception

)

while"i#

)ds/new DatagramSoc,et"#(

DataInputStream in/new DataInputStream"S$stem.in#(

S$stem.out.println"0-nter the message0#(str/in.readine"#(

buff/str.get&$tes"#(

dp/new Datagram@ac,et"buffBbuff.lengthBInetAddress.getocal!ost"#B


6/91

RECEIER:'

import java.io.'(

import java.net.'(class Geceiver

)DatagramSoc,et ds(

Datagram@ac,et dp(

b$te buff*+/new b$te*458H+(

String str(public void receiver"# throws IC-ception

)

ds/new DatagramSoc,et"


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O&TP&T:

SENDER:'

-21cn7javac Sender.java

-21cn7java Sender

-nter the message2 hi

Do $ou want to continue Ees or %o

%o

RECEIER:

-21cn7javac Geceiver.java

-21cn7java Geceiver

essage received2 hi

Ip Address2 94:8.4;


8/91

EX0NO: ! TCP' ONE (A) COMM&NICATIONS

AIM:

To write a java program to implement o*e +ay ,omm-*.,at.o* -s.*/ TCP0

ALGORITHM:

SERER:'

STEP 1:Start the program.

STEP :Import net pac,age and other pac,ages.

STEP !:Declare object for ServerSoc,etB Soc,et and @rintStream to transfer data.

STEP ":Using @rintStream transfer the data in CutputStream via a port.

STEP #:Gun a loop to send data from server until an J-%D or -KITL string is

transferred.

STEP $:If J-%D or -KITL is encounteredB close the soc,ets and eit the loop.

CLIENT:'


STEP :Import net pac,age and other pac,ages.

STEP !:Declare object for Soc,et and DataInputStream to receive server data.

STEP ":Gun a loop to receive data from server and store it in a string using

DataInputStream.

STEP #:@rint the string to displa$ the server data and eit when an J-%D or -KITL

message is encountered .


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PROGRAM:

SERER:'

import java.io.'(

import java.net.'(

class Server)

public static void main"String a*+#throws IC-ception

)Serversoc,et ss/ new ServerSoc,et"


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O&TP&T:

SERER:'

-21cn7Server.java

-21cn7java Server

-nter the message to send2

=omputer networ,

-%D

CLIENT:'

-21cn7javac =lient.java

-21cn7java =lient

essage Geceived2

=omputer networ,

-%D

RES&LT:

Thus the java program implementing TCP' o*e +ay ,omm-*.,at.o*has been

successfull$ coded and eecuted

EX: NO: "a IMPLEMENTATION OF ECHO COMMAND


11/91

AIM:

To write a java program to demonstrate the -=!C command.

ALGORITHM:

SERER:'

STEP1:Start

STEP:Import net pac,age and other pac,ages.

STEP!:Declare objects for DataInputStreamB soc,et and @rintMriter to receive server

and sendit bac,.

STEP":Store message in a string and print message using print method.

STEP#: Send the same received message to server using @rintMriter and Soc,et.

STEP$:Mhen received message is -%D then eit program eecution.

CLIENT:'

STEP1:Start

STEP:Import net pac,age and other necessar$ pac,ages.

STEP!:Declare objects from ServerSoc,et and Soc,et.

STEP":Declare Cbjects for @rintStream to write message from server to client.

STEP#:>et user input and store it in a string.

STEP$:Using print method receive client echo message and print it.

STEP%:Terminate program when message is sent.

PROGRAM:


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ECHO SERER:'

import java.io.'(

import java.net.'(class -choServer

)public static void main"String a*+#

)tr$

)

Soc,et s/null(ServerSoc,et ss/new ServerSoc,et"


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DataInputStream in/new DataInputStream"S$stem.in#(

&ufferedGeader br4/new &ufferedGeader "new InputStreamGeader"S$stem.in##(

&ufferedGeader br8/new &ufferedGeader "new InputStreamGeader"s.getInputStream"###(@rintMriter print/new @rintMriter"s.getCutputStream"##(

S$stem.out.println"Jessage to be echoed20#(String str/br4.readine"#(

print.println"str#(

print.flush"#(S$stem.out.println"br8.readine"##(

6

catch"Un,nown!ost-ception e#

)6

catch"IC-ception e#

)

S$stem.out.println"0error203e#(6

66

O&TP&T:


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ECHO SERER:'

-21cn7javac -choServer.java

-21cn7java -choServer

Soc,et*addr/94:8.4;


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AIM:

To write a java program to implement the PING ,omma*d.

ALGORITHM:


STEP :Import net and pac,ages.

STEP !:Initiali?e the ping server with both soc,ets as null value.

STEP ":Start the ServerSoc,et at the clientand give the I@ address of the server.

STEP #:The client program is then started b$ starting soc,et.

STEP $: At the receiver endB the server is pinged.

PROGRAM:


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SERER:'

import java .io.'(

import java.net.'(public class @server

)public static void main"String a*+#

)String line4Bline8(

int i(

ServerSoc,et ss(DataInputStream di(

@rintStream ps(

Soc,et soc(ss/null(

soc/null(

tr$)

ss/new ServerSoc,et"::::#(

6

catch"-ception e#)

S$stem.out.print"e#(

6

S$stem.out.println"0@ing server0#(

tr$)

soc/ss.accept"#(

di/new DataInputStream"soc.getInputStream"##(

ps/new @rintStream"soc.getCutputStream"##(for"i/5(iN(i33#

)

line4/di.readine"#(S$stem.out.println"0@inged b$ client0#(

ps.println"line430repl$ from host2b$tes/H8 timeNms TT/48O0#(

6di.close"#(

ps.close"#(

6catch"-ception e#

)

S$stem.out.print"e#(

66 6

CLIENT:'


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import java.io.'(

import java.net.'(

public class @client)

public static void main"String a*+#

)@rintMriter out/null(

int iBjB,(

&ufferedGeader networ,In/null(tr$

)

S$stem.out.print"0-nter I@ Address20#(

DataInputStream in/new DataInputStream"S$stem.in#(String ip/in.readine"#(

Soc,et theSoc,et/new Soc,et"ipB::::#(

networ,In/new &ufferedGeader"new InputStreamGeader"S$stem.in##(

out/new @rintMriter"theSoc,et.getCutputStream"##(S$stem.out.print"0pinging 03ip30 with H8 b$tes of data0#(

for"i/5(iN(i33#)

out.println"ip#(

out.flush"#(

String inp/networ,In.readine"#(

if"inpP/null#

)for"j/5(jN45555(j33#

)

for",/5(,NO5555(,33#)66

S$stem.out.println"0Gepl$ from03inp#(

6else

)

for"i/5(iN(i33#

)for"j/5(jN45555(j33#

)

for",/5(,NO5555(,33#)6S$stem.out.println"01n GeFuested time out0#(

6

66

6

6

catch"IC-ception e#


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)

for"i/5(iN(i33#)

for"j/5(jN45555(j33#

)for",/5(,NO5555(,33#)6

6

S$stem.out.println"01n GeFuested time out0#(6

6

tr$

)if"networ,InP/null#

networ,In.close"#(

if"outP/null#

out.close"#(6catch"-ception e#

)S$stem.out.println"01n GeFuested time out0#(

6

66

O&TP&T:


19/91

SERER:'

-21cn7javac @ingServer.java

-21cn7java @ingServer

@ing server

@inged b$ client

CLIENT:'

-21cn7javac @ing=lient.java

-21cn7java @ing=lient

-nter I@ Address2

4;:.8O.4.8

@inging 4;:.8O.4.8 with H8 b$tes of data

Gepl$ from 4;:.8O.4.4 Gepl$ from2 b$tes/H8 timeN 4 ms TT/48et an user input in the form of bit data is string.

STEP":>et an generator data from the user

.

STEP#:Gead the length of the string and convert the data into another format b$

deducing < from it.

STEP$:%ow add the generator data to the original data and send the string as

transmitter string.

STEP%:In the receiving endB enter the generator code.

STEP5:Using the generator codeB to the length of the received stringB add < to the

. number format of the string b$ character

STEP7:If the generator string is wrongB displa$ Jmessage received with error.L

STEP18:If the generator string is correctB perform step < and displa$ Jmessage

received with no error.L

STEP11:-nd the program.

PROGRAM:

import java.io.'(


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import java.lang.'(

public class crc

)

public static void main"String args*+#throws IC-ception

)

int f*+/new int*8O+(

int gen*+/new int*45+(

int rem*+/new int*45+(

int flenBglenBrlenBiBj(

int pBsumBiframeBigenBirem(

String data(

&ufferedGeader in/new &ufferedGeader"new InputStreamGeader"S$stem.in##(

S$stem.out.print"01n-%T-G %-M GA- 20#(

data/in.readine"#(

flen/data.length"#4(for"i/5(iNdata.length"#(i33#

f*i+/""int#"data.charAt"i###


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irem/iframeYigen(

irem/igenirem(

iframe3/irem(

i/5(

while"iframe75#

)

f*i+/iframeY8(

iframe/iframe98(

i33(

6

if"iframe//4#

f*i+/iframe(

S$stem.out.print"01n1nTGA%SITT-D STGI%> 20#(

for"i/flen(i7/5(i#

S$stem.out.print"f*i+#(S$stem.out.print"01n1n-%T-G T!- G-=-IR-D STGI%> 20#(

data/in.readine"#(

flen/data.length"#4(

for"i/5(iNdata.length"#(i33#

f*i+/""int#"data.charAt"i###


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45454

TGA%SITT-D STGI%>

45455454

-%T-G T!- G-=-IR-D STGI%>

45454

-SSA>- G-=-IR-D MIT! %C -GGCG

RES&LT:

Thus the java program implementing the process of ,y,9., red-*da*,y ,he, has

been successfull$ coded and eecuted.

EX: NO: 5 ONE ;IT SLIDING (INDO( PROTOCOL

AIM:


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To write a java program to implement the process of o*e 2.t s9.d.*/ +.*do+


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STEP 18:=ontinue the process till all the specified number of frames are sent and

ac,nowledgement is received

STEP 11:Mhen all the frames are sent and ac,nowledgement is received eit

the program.

PROGRAM:

SERER:'

import java.lang.s$stem(

import java.net.'(


39/91

import java.io.'(

class Server4

)public static void main"String args*+#

)

tr$)

&uferedInputStream in(

ServerSoc,et ss / new ServerSoc,et"O555#(S$stem.out.println"JMaiting for connectionL#(

Soc,et client / ss.accept"#(

S$stem.out.println"JGeceived reFuest for sending framesL#(

in / new &ufferedInputStream"client.getInputStream"##(DataCutputStream out/ new DataCutputStream"client.getCutputStream"##(

int p/ in.read"#(

S$stem.out.println"JSendingL#(

for"int i/4( iN/p( 33i#)

S$stem.out.println"JSending frame no2L3i#(

out.write"i#(

out.flush"#(S$stem.out.println"Jwaiting for ac,nowledgeZL#(

Thread.sleep"O555#(

int a/ in.read"#(

S$stem.out.println"JGeceived ac,nowledge for frame no23i3LasL 3a#(6

out.flush"#(

in.close"#2out.close"#(

client.close"#(

ss.close"#(S$stem.out.println"J[uiting..L#(

6catch"IC-ception e#

)

S$stem.out.println"e#(6catch"Interrupted-ception e#)6

6

6

CLIENT:'

import java.lang.'(

Import java.net.'(

import java.io.'(


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import java.math.'(

class =lient4

)public static void main"String *+args#

)

tr$)

InetAddress addr / InetAddress.get&$%ame"Jocal!ostL#(

S$stem.out.println"addr#(Soc,et connection/ new Soc,et"addrBO555#(

DataCutputStream out/ new DataCutputStream"connection.getCutputStream"##(

&ufferedInputStream in / new &ufferedInputStream"connection.getInputStream"##(

&ufferedInputStream inn/ new &ufferedInputStream"connection.getInputStream"##(&ufferedGeader ,i/ new &ufferedGeader"new InputStreamGeader"S$stem.in##(

int flag /5(

S$stem.out.println"JconnectedZL#(

S$stem.out.println"J-nter no. of frames to reFuested to server2L#(int c/ Integer.parseInt",i.readine"##(

out.write"c#(out.flush"#(

int iB jj/5(

while"jjNc#)

i/ in.read"#(

S$stem.out.println"JGeceived frame no2L3i#(

S$stem.out.println"JSending ac,nowledgement for frame no2L3i#(

out.write"i#(

out.flush"#(jj33(

6

out.flush"#(in.close"#2

inn.close"#(

out.close"#(

connection.close"#(S$stem.out.println"J[uiting..L#(

6

catch"-ception e#)

S$stem.out.println"e#( 6 6 6

O&TP&T:

SERER:'

-21cn7javac Server4.java


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-21cn7 java Server4

Maiting for connection

Geceived reFuest for sending frames

Sending

Sending frame no24

Maiting for ac,nowledgeZ

Geceived ac,nowledge for frame no24 as 4

[uitting..

CLIENT:'

-21cn7javac =lient4.java

-21cn7 java =lient4

ocal!ost

=onnectedZ

-nter the no. of frames to reFuested to server2

4

Geceived frame no24

Sending ac,nowledgment for frame no24

[uittingZ.

RES&LT:

Thus the java program implementing the O*e 2.t s9.d.*/ +.*do+


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To write a java program to implement FTP -s.*/ TCP.

ALGORITHM:

SERER:'

STEP1: Start the program.

STEP:Import net and other pac,ages.

STEP!:Declare object for ServerSoc,et and Soc,et to send a file.

STEP": Declare objects for ileCutputStream to write into a file.

STEP#:>et the filename from the user an dt$pe the file using ileCutputStream"#

conent.

CLIENT:'

STEP1:Start the program.

STEP:Import net and other pac,ages.

STEP!: Declare objects for Server and ileInputStream to write the server file into

server

STEP":Using the InputStream method receive the filename and print the received

file name

STEP#:=reate a new client file using ileInputStream and write the contents of the

server file into it using ileCutputSream.

STEP $:Mhile writingB read the source file as characters and write into the other file.

STEP %:-nd the program after writing into the client file.

PROGRAM:

FILE SERER:'

import java.net.'(

import java.io.'(


43/91


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ileCutputStream fos / new ileCutputStream"fname3L.ttL#(

&ufferedCutputStream bos/ new &ufferedCutputStream"fosB85


45/91

-21cn7java ileServer

-nter the filename2

ile

=omputer networ,

\

FILE CLIENT:'

-21cn7javac ile=lient.java

-21cn7java ile=lient

Geceived file2 ile

-nter the new file name2

ile4

RES&LT:

Thus the java program implementing T@ using T=@ has been successfull$

coded and eecuted.

EXNO: 18a T(O (A) COMM&NICATION &SING TCP=IP

AIM:'

To write a java program to perform JT+o (ay Comm-*.,at.o* &s.*/ TCP=IPL.

ALGORITHM:


46/91

SERER:'

STEP12 Import the java pac,age and create class TwoServerT=@.

STEP2 String of argument is passed to the args *+.

STEP!2 =reate a new server soc,et and bind it to the port.

STEP"2 Accept the client connection at the reFuested port.

STEP#2 Cverride the methods of output stream

.

STEP$2 &$ using data input stream a message is received from clientserver andW

that message are echoed to client again b$ print stream.

STEP%2 Mrite message at the soc,et.

STEP52 If the read line is J-itL then close the client connection.

STEP72 -nd of main.

STEP182 -nd of TwoServerT=@ class.


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CLIENT:'

STEP12 Import the java pac,age and create class Two=lientT=@.


STEP!2 =reate a new soc,et reFuesting for communication with server.

STEP"2 =reate objects for buffered reader V inputs stream.

STEP#2 &$ using data input stream a message is received from clientserver andW

that message are echoed to client again b$ print stream.

STEP$2 Cverride the methods of input stream.

STEP%2 Gead the message from the soc,et.

STEP52 -nd of main

.

STEP72 -nd of Two=lientT=@ class.


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SERER SIDE:'

import java.net.'(

import java.io.'(class TwoServerT=@

)public static void main"String args*+#throws IC-ception)

Tr$

)

ServerSoc,et ss/new ServerSoc,et";5#(Soc,et sc(

S$stem.out.println"0Maiting or =lient...0#(

sc/ss.accept"#(&ufferedGeader in/new &ufferedGeader"new W

InputStreamGeader"sc.getInputStream"###(

@rintMriter out/new @rintMriter"sc.getCutputStream"#Btrue#(&ufferedGeader stdin/new &ufferedGeader"new W

InputStreamGeader"S$stem.in##(

String aBb(

S$stem.out.println"0=onnected To =lient...03sc#(while"true#

)

S$stem.out.print"0-nter The essage or =lient20#(

a/stdin.readine"#(

if"a.eFuals"0-it0##

brea,(out.flush"#(

out.println"a#(b/in.readine"#(

S$stem.out.print"0=lient Sa$s203b#(

6

sc.close"#(6

catch"-ception e#

)S$stem.out.println"0-rror03e#(

66 6


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CLIENT SIDE:'

import java.io.'(import java.net.'(

class Two=lientT=@

)public static void main"String args*+#throws IC-ception)

tr$

)Soc,et sc(

if"args.lengthP/4#

sc /new Soc,et"0ocal!ost0B;5#(else

sc/new Soc,et"0SEST-0B;5#(

&ufferedGeader in/new &ufferedGeader"new W

InputStreamGeader"sc.getInputStream"###(@rintMriter out/new @rintMriter"sc.getCutputStream"#Btrue#(

&ufferedGeader stdin/new &ufferedGeader"new

InputStreamGeader"S$stem.in##(String aBb(

S$stem.out.println"0Maiting or Server...0#(

S$stem.out.println"0=onnected To Server...03sc#(b/in.readine"#(

S$stem.out.println"0Server Sa$s203b#(

while"true#)

S$stem.out.println"0-nter The essage or Server20#(a/stdin.readine"#(

if"a.eFuals"0-it0##brea,(

out.println"a#(

b/in.readine"#(S$stem.out.print"0Server Sa$s203b#(

6

sc.close"#(6

catch"-ception e#

)S$stem.out.println"0-rror03e#(6

6


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O&TP&T:'

SERER O&TP&T:'

=21jd,4.H1bin7javac [email protected]

=21jd,4.H1bin7java TwoServerT=@

Maiting or =lient...

=onnected To =lient...

Soc,et*addr/localhost948X.5.5.4Bport/HO5:Blocalport/;5+

-nter The essage or =lient2!ai

=lient Sa$s2!ai...!ow Are U

-nter The essage or =lient2Ea ine...

=lient Sa$s2null-nter The essage or =lient2-it

=21jd,4.H1bin7

CLIENT O&TP&T:'

=21jd,4.H1bin7javac [email protected]

=21jd,4.H1bin7java Two=lientT=@

Maiting or Server...

=onnected To Server...

Soc,et*addr/ocal!ost948X.5.5.4Bport/;5Blocalport/HO5:+

Server Sa$s2!ai

-nter The essage or Server2!ai...!ow Are U

Server Sa$s2Ea ine...

-nter The essage or Server2-it

=21jd,4.H1bin7

RES&LT:'

Thus the program has been eecuted and the output is verified successfull$.


51/91

EX: NO: 182 T(O (A) COMM&NICATION' &DP

AIM:

To write a java program to implement t+o +ay ,omm-*.,at.o* -s.*/ &DP0

ALGORITHM:

SERER:'

STEP1: Import the net and other pac,ages.



STEP": >et the buffer si?e and I@ Address of local host and communication

with the client.

STEP#:Send the Datagram pac,et to the destination address of given port.

STEP$:Store the input in the buffer at the specific location.

CLIENT:'




STEP":=reate pac,et for receving arra$ of b$tes with maimum b$tes.

STEP#:Specif$ the common port for connecting datagram soc,et.


52/91

PROGRAM:

SENDER:'

import java.io.'(

import java.net.'(

class Sender)

public static void main "String a*+#throws -ception

)while"true#

)

DatagramSoc,et ds / new DatagramSoc,et"#(&ufferedGeader br / new &ufferedGeader"new InputStreamGeader"S$stem.in##(

S$stem.out.println"0-nter the message20#(

String msg/br.readine"#(

b$te b*+/msg.get&$tes"#(InetAddress add/InetAddress.getocal!ost"#(

Datagram@ac,et dp/new Datagram@ac,et"bBb.lengthBaddB48H#(

ds.send"dp#(if"msg.eFuals"0-KIT0##

S$stem.eit"5#(

b$te b4*+/new b$te*8OO+(Datagram@ac,et dp4/new Datagram@ac,et"b4Bb4.length#(

ds.receive"dp4#(

String msg4/new String"dp4.getData"##(

S$stem.out.println"0Geceived message203msg4#(

666

RECEIER:'

import java.io.'(

import java.net.'(class Geceiver

)

public static void main"String a*+#throws IC-ception)

DatagramSoc,et ds/new DatagramSoc,et"48H#(

b$te b*+/new b$te*8OO+(

while"true#)

Datagram@ac,et dp/new Datagram@ac,et"bBb.length#(

ds.receive"dp#(


53/91

String msg/new String"dp.getData"##(

S$stem.out.println"0essage Geceived203msg#(

InetAddress add/dp.getAddress"#(int port/dp.get@ort"#(

S$stem.out.println"0-nter the message to send20#(

&ufferedGeader br/new &ufferedGeader"new InputStreamGeader"S$stem.in##(

String msg4/br.readine"#(

b$te b4*+/msg4.get&$tes"#(Datagram@ac,et dp4/new Datagram@ac,et"b4Bb4.lengthBaddBport#(

ds.send"dp4#(

if"msg4.eFuals"0-KIT0##

S$stem.eit"5#(6

6

6


54/91

O&TP&T:

SENDER:'

-21cn7javac Sender.java

-21cn7java Sender

-nter the message2 hi

Geceived message2 hi

-nter the message2

-KIT

RECEIER:'

-21cn7javac receiver.java

-21cn7java Geceiver

essage Geceived2 hi

-nter the message to send2 hi

essage Geceived2 -KIT

RES&LT:

Thus the java program implementing UD@> t+o +ay ,omm-*.,at.o* has been

successfull$ coded and eecuted.


55/91

EX0NO:11 REMOTE METHOD INOCATION

AIM:

To write a java program to implement remote method .*4o,at.o* ?rm.@0

ALGORITHM:

STEP 1:Start

STEP :-stablish the connection between the client and the server to calculate

factorial operation

STEP !:In imple"# it calls the inter"# which throws eception thrown b$ fact"#.

STEP ":In the client UG has been specified and declared as String.

STEP #:It calls the inter"# to connect with the imple"# and getthe result.

STEP $:Stop.


56/91

PROGRAM:

RMI SERER:'

import java.rmi.'(

import java.net.'(

import java.io.'(public class server

)

public static void main"String args*+#throws -ception

)imple c/new imple"#(

java.rmi.%aming.rebind"0server0Bc#(

S$stem.out.println"0S-GR-G G-ADE...0#(

66

RMI CLIENT:'

import java.rmi.'(

import java.net.'(import java.io.'(

public class client

)public static void main"String args*+#throws -ception

)&ufferedGeader br/new &ufferedGeader"new InputStreamGeader"S$stem.in##(inter s/"inter#java.rmi.%aming.loo,up"0rmi299ocal!ost9server0#(

S$stem.out.println"0-nter a %o 2 0#(

int n/Integer.parseInt"br.readine"##(

s.fact"n#(6

6

RMI IMPLEMENT:'

import java.rmi.'(import java.net.'(

import java.rmi.server.'(

public class imple etends java.rmi.server.UnicastGemoteCbject implements inter)

public imple"#throws java.rmi.Gemote-ception

)


57/91

6

public void fact"int n#throws java.rmi.Gemote-ception

)int f/4(

for"int i/4(iN/n(i33#

f/f'i(S$stem.out.println"0actorial of 03n30is 2 03f#(

6

6

RMI INTERFACE:'

import java.rmi.'(

public interface inter etends java.rmi.Gemote

)

public void fact"int n#throws java.rmi.Gemote-ception(6


58/91


59/91

EX: NO: 1 SHORTEST PATH RO&TING ALGORITHM

AIM:

To write a java program to implement shortest path routing algorithm.

ALGORITHM:

STEP1:Import the java pac,age and create class spath.


STEP!:Gead the distance b9w pair of nodes.

STEP":If eitsB then get the source and destination node.

STEP#:rom the source nodeB find the possible path and record.

STEP$:Ta,e the smallest path among these path repeat the process till the W

destination is reached.

STEP%:-nd of main.

STEP5:-nd spath class.


60/91

PROGRAM:

import java.net.'(import java.io.'(

class spath

)public static void main"String args*+#throws IC-ception

)

int nBsBdBiBjB$/5Bsd/455(int*+ in/new int*45+(

int*+*+ m/new int*O+*O+(

int*+ dis/new int*45+(

int*+ path/new int*45+(DataInputStream a/new DataInputStream"S$stem.in#(

S$stem.out.print"0-%T-G T!- %U&-G C R-GT-K 2 0#(

n/Integer.parseInt"a.readine"##(

S$stem.out.print"0-%T-G T!- SCUG=- R-GT-K 2 0#(s/Integer.parseInt"a.readine"##(

S$stem.out.print"0-%T-G T!- D-STI%ATIC% R-GT-K 2 0#(d/Integer.parseInt"a.readine"##(

for"i/4(iNn(i33#

)j/4(

while"jNn#

)

S$stem.out.print"0-%T-G T!- DISTA%=- &-TM--% 03i30 A%D 03"j34#302 0#(m*i+*j34+/Integer.parseInt"a.readine"##(

m*j34+*i+/m*i+*j34+(

j33(6

6

for"i/4(iN/n(i33#)

in*i+/5(

dis*i+/m*s+*i+(

if"m*s+*i+P/5#path*i+/s(

6

in*s+/4(dis*s+/5(

for"i/8(iNn(i33#

)for"j/4(jN/n(j33#

)

if"in*j+//5#

)


61/91

if"dis*j+Nsd#

)

sd/dis*j+($/j(

6

66

in*$+/4(

for"j/4(jN/n(j33#)

if""in*j+//5#VV"m*$+*j+P/5##

)

if""dis*$+3m*$+*j+#Ndis*j+#)

dis*j+/dis*$+3m*$+*j+(

path*j+/$(

66

66

S$stem.out.print"003d30N0#(

i/d(while"path*i+P/s#

)

S$stem.out.print"003path*i+30N0#(

i/path*i+(6

S$stem.out.print"003s#(

S$stem.out.print"01nDISTA%=- IS 203dis*d+#(6

6


62/91

O&TP&T:

-21cn7javac [email protected]

-21cn7java Short@ath

-nter The %o.Cf Rertices2

-nter The =ost Cf atri2

Mhether -dges -ist &9M 4 And 8 *4EesB5%o+.

4

-nter The Meight or -dge 4 To 8

O

Mhether -dges -ist &9M 4 And H *4EesB5%o+.

5

Mhether -dges -ist &9M 4 And *4EesB5%o+.

4

-nter The Meight or -dge 4 To

Mhether -dges -ist &9M 8 And 4 *4EesB5%o+.

4

-nter The Meight or -dge 8 To 4

X

Mhether -dges -ist &9M 8 And H *4EesB5%o+.

5

Mhether -dges -ist &9M 8 And *4EesB5%o+.

4

-nter The Meight or -dge 8 To

8

Mhether -dges -ist &9M H And 4 *4EesB5%o+.

5

Mhether -dges -ist &9M H And 8 *4EesB5%o+.

4


63/91

-nter The Meight or -dge H To 8

H

Mhether -dges -ist &9M H And *4EesB5%o+.

5

Mhether -dges -ist &9M And 4 *4EesB5%o+.

5

Mhether -dges -ist &9M And 8 *4EesB5%o+.

5

Mhether -dges -ist &9M And H *4EesB5%o+.

4

-nter The Meight or -dge To H

4

-nter The Source Rerte24

The Q Ralue Is2

5

4

4

The Q Ralue Is28

5

4

4

The Q Ralue Is2H

5

4

4

@ath*4+/5

Distance*4+/5


64/91


65/91

EX: NO: 1!a ;ROADCASTING

AIM:

To write a java program to implement the process of 2road,ast.*/.

ALGORITHM:

SERER:'


STEP :Import the net and other pac,ages.

STEP !:The DatagramSoc,et and the DataInputstream are initiali?ed.

STEP ":The buffer is declared for message.

STEP #:The message is obtained from the user.

STEP $:The message is delivered to the client one b$ one with the help of the

Datagram@ac,et.

STEP %:The client details is obtained

STEP%:@ac,ets are then sent to the reciver b$ the help od Datagram soc,et.

STEP5:If message is b$e then the server Fuits.

CLIENT:'


STEP:Import net and other pac,age.

STEP!: The DatagramSoc,et and Datagram@ac,et are initiali?ed.

STEP":The message from sender is ta,en as the pac,etfrom buffer.

STEP#: The message is displa$ed along with the I@ address of the server.

STEP$:If the message isb$e then the client Fuits.


66/91

PROGRAM:

SERER:'

import java.io.'(

import java.net.'(

public class &roadServer)

public static void main"String args*+# throws -ception

)DatagramSoc,et ds / new DatagramSoc,et"#(

DataInputStream dis / new DataInputStream"S$stem.in#(

String msg/ 00(String client / 00(

b$te*+ buf / new b$te*458+(

while"true#

)S$stem.out.println"0Server0#(

msg/ dis.readine"#(

buf/ msg.get&$tes"#(for"int i/4( iN/45( i33#

)

tr$)

client / "0s$sL3i#(

Datagram@ac,et dp/ new Datagram@ac,et "bufBbuf.lengthBInetAddress.get&$%ame"client#BO555#(

ds.send"dp#(

S$stem.out.println"0essage Sent To2 03client#(6catch"-ception e#

)

S$stem.out.println"0Unable To =onnect At...03client3e#(6

if"msg.eFualsIgnore=ase"0&$e0##

)S$stem.out.println"0Server [uits0#(

return(

6

66

6

6


67/91

CLIENT:'

import java.net.'(

import java.io.'(

public class &road=lient


)

DatagramSoc,et ds/ new DatagramSoc,et"O555#(while"true#

)

tr$)

b$te*+ buf/new b$te*458+(

DataInputStream dis/ new DataInputStream"S$stem.in#(String msg/ null(

Datagram@ac,et dp/ new Datagram@ac,et"bufBbuf.length#(ds.receive"dp#(

msg/new String"dp.getData"#B5Bdp.getength"##(InetAddress ia/dp.getAddress"#(

S$stem.out.println"0rom2 03ia30 essage2 03msg#(

if"msg.eFualsIgnore=ase"0&$e0##)

S$stem.out.println"0=lient [uits0#(

return(6

6

catch"-ception e#)S$stem.out.println"J-rrorL3e#(

6

66

6


68/91

O&TP&T:

SERER:'

-21cn7javac &roadServer.java

-21cn7java &roadServer

Server2 hai

essage successfull$ sent to =lient2 s$s4

Unable To =onnect at2 s$s8java.net.Un,nown!ost-ception2 s$s82 s$s8

Unable To =onnect at2 s$sHjava.net.Un,nown!ost-ception2 s$sH2 s$sH

Unable To =onnect at2 s$sjava.net.Un,nown!ost-ception2 s$s2 s$s

Unable To =onnect at2 s$sOjava.net.Un,nown!ost-ception2 s$sO2 s$sO

Unable To =onnect at2 s$s;java.net.Un,nown!ost-ception2 s$s;2 s$s;

Unable To =onnect at2 s$sXjava.net.Un,nown!ost-ception2 s$sX2 s$sX

Unable To =onnect at2 s$s


69/91

OTHER:

-21cn7 javac &road=lient.java

-21cn7java &road=lient

rom2 94;:.8O.4.8 essage2 hai

-21cn7 javac &road=lient.java

-21cn7java &road=lient

Server2

-21cn7

RES&LT:

Thus the java program implementing the process of 2road,ast.*/has been successfull$

coded and eecuted.


70/91

EXNO: 1!2 M&LTICASTING

AIM:'

To write a java program to perform JM-9t.,ast.*/L.

ALGORITHM:

SERER:'

STEP12 Import the java pac,age and create class ultiServer.


STEP!2 irst we enable the soc,et object for multicasting soc,et.

STEP"2 Using the soc,et objectBwe join the multicast group using the host name.

STEP#2 Cnce we join the group the message is read from the server and it is send to

the client.

STEP$2 Similarl$ the soc,et object to recive the message from client side is enabled

and using the get data methodBwe recive the pac,ets through the given port.

STEP%2 Mhen it reaches J&$eL it Fuits from the group.

STEP52 -nd of main

.

STEP72 -nd of ultiServer class.


71/91

CLIENT:'

STEP12 Import the java pac,age and create class ulti=lient.


STEP!2 !ere using the soc,et we join the multicast group.

STEP"2 Using the Datagram pac,ets object Bwe read the message b$ string in W

buffered arra$ .

STEP#2 Similarl$ b$ using readine method input got from client as b$te.

STEP$2 The message is passed using the soc,et object using read method in the W

enabled port.

STEP%2 -nd of main.

STEP52 -nd of &road=lient class.


72/91

SERER SIDE:'

import java.net.'(

import java.io.'(

class ultiServer


)

ulticastSoc,et soc,et(

Datagram@ac,et pac,et(

String msgBmsg4Bmsg8(

b$te*+ buf/new b$te*O555+(

DataInputStream one/new DataInputStream"S$stem.in#(

soc,et/new ulticastSoc,et"#(

soc,et.join>roup"InetAddress.get&$%ame"088.5.5.40##(

S$stem.out.println"01n1nocalI@2 03InetAddress.getocal!ost"##(

while"true#

)

S$stem.out.println"0essage !ere20#(

msg4/one.readine"#(

msg8/ InetAddress.getocal!ost"#.toString"#(

msg/msg430030rom Server03msg8(

buf/msg.get&$tes"#(

pac,et/ new

Datagram@ac,et"bufBbuf.lengthBInetAddress.get&$%ame"04;:.8O.85.


73/91

CLIENT SIDE:'


class ulti=lient


)

ulticastSoc,et soc,et/new ulticastSoc,et"O#(soc,et.join>roup"InetAddress.get&$%ame"088.5.5.40##(

String msgBmsg4Bmsg8(

DataInputStream one/new DataInputStream"S$stem.in#(

b$te*+ buf/new b$te*4O55+(S$stem.out.println"0ocal I@2 03InetAddress.getocal!ost"##(

while"true#

)

Datagram@ac,et pac,et/new Datagram@ac,et"bufBbuf.length#(

soc,et.receive"pac,et#(msg/new String"pac,et.getData"#B5Bpac,et.getength"##(

S$stem.out.println"0essage2 03msg#(

int c/45(char c4*+/new char*c+(

msg.get=hars"5BHBc4B5#(

String temp/0 0(

for"int i/5(iNH(i33#)

temp/temp3c4*i+(

6if"temp.eFualsIgnore=ase"0&$e0##

)

S$stem.out.println"0=lient [uits0#(return(

6

msg/null(

buf/new b$te*4555+(S$stem.out.println"0essage2 0#(

msg4/one.readine"#(

msg8/InetAddress.getocal!ost"#.toString"#(msg/msg430 030rom =lient2 03msg8(

buf/msg.get&$tes"#(

InetAddress address/pac,et.getAddress"#(int port/pac,et.get@ort"#(

pac,et/new Datagram@ac,et"bufBbuf.lengthBaddressBport#(

soc,et.send"pac,et#(

6 6 6


74/91


75/91

AIM:

To write a java program to implement Address Reso9-t.o* Proto,o9.

ALGORITHM:

CLIENT SIDE:

STEP1:-stablish a connection between the =lient and Server.

Soc,et ss/new Soc,et"InetAddress.getocal!ost"#B4455#(

STEP:=reate instance output stream writer .@rintMriter ps/new @rintMriter"s.getCutputStream"#Btrue#(

STEP!:>et the I@ Address to resolve its ph$sical address.

STEP":Send the I@Address to its output Stream.ps.println"ip#(

STEP#:@rint the @h$sical Address received from the server.

SERER SIDE:

STEP12 Accept the connection reFuest b$ the client.

ServerSoc,et ss/new ServerSoc,et"8555#( Soc,et s/ss.accept"#(

STEP2 >et the I@address from its inputstream.&ufferedGeader br4/new

&ufferedGeader"new InputStreamGeader"s.getInputStream"###(

ip/br4.readine"#(

STEP!2 During runtime eecute the process Guntime r/Guntime.getGuntime"#(

@rocess p/r.eec"0arp a 03ip);

STEP":Send the @h$sical Address to the client.

PROGRAM:


76/91


77/91

&ufferedGeader br4/new &ufferedGeader"new InputStreamGeader"s.getInputStream"###(

String ip(

ip/br4.readine"#(Guntime r/Guntime.getGuntime"#(

@rocess p/r.eec"0arp a 03ip#(

&ufferedGeader br8/new &ufferedGeader"new InputStreamGeader"p.getInputStream"###(String str(

while""str/br8.readine"##P/null#

)ps.println"str#(

6

6

catch"IC-ception e#)

S$stem.out.println"0-rror03e#(

6

6 6

O&TP&T


78/91

=21%etwor,ing @rograms7java ArpServer

=21%etwor,ing @rograms7java Arp=lient

-nter the I@ADDG-SS2

4:8.4;


79/91

EX0NO:1# CR)PTOGRAPH)

AIM:

To write a java program to implement the ,9.e*t ser4er ,ry


80/91

STEP":Store the string and the ,e$ to different variabls.

STEP#:Gead the string character wise to its length.

STEP$:GeFuest the user to enter the ,e$ for decr$ption.

STEP%:=ompare the ,e$ with received ,e$.

STEP5:If both the ,e$s are eFual thenB

=onvert the each character of the string to integer and deduce the ,e$ value.

=onvert the integer value to character and form it into a string and displa$ the

decr$pted string.

-lse

@rint the message as cannot decr$ptB wrong message and Fuit.

STEP7:-nd the program.

PROGRAM:


81/91

SERER:


class eser

)public static void main"String args*+# throws -ception)

tr$

)ServerSoc,et ss/new ServerSoc,et":555#(

Soc,et s/ss.accept"#(

@rintStream ps/new @rintStream"s.getCutputStream"##(&ufferedGeader br/new &ufferedGeader"new InputStreamGeader"S$stem.in##(

int i/5B,(

String s8/0 0(

S$stem.out.println"01n -%T-G A STGI%>20#(String s4/br.readine"#(

S$stem.out.print"01n -%T-G T!- Q-E20#(

,/Integer.parseInt"br.readine"##(while"iNs4.length"##

)

char c4/s4.charAt"i33#(int n/"int#c43,34(

c4/"char#n(

s83/c4(6

S$stem.out.println"0-%=GE@T-D STGI%> IS203s8#(ps.println"s8#(

ps.println",#(ps.close"#(

s.close"#(

ss.close"#(6

catch"-ception e#

)S$stem.out.println"01n -GGCG203e#(

6

66

CLIENT:


82/91

import java.io.'(

import java.net.'(class ecli

)

public static void main"String args*+# throws -ception)

Soc,et s/new Soc,et"0ocal!ost0B:555#(

&ufferedGeader br/new &ufferedGeader"new InputStreamGeader"s.getInputStream"###(int i/5B,4(

&ufferedGeader br4/new &ufferedGeader"new InputStreamGeader"S$stem.in##(

String sH/0 0(

String s8/br.readine"#(int ,/Integer.parseInt"br.readine"##(

S$stem.out.println"0G-=-IR-D S>203s8#(

S$stem.out.println"01n -%T-G T!- Q-E20#(

,4/Integer.parseInt"br4.readine"##(if",//,4#

)while"iNs8.length"##

)

char c4/s8.charAt"i33#(int n/"int#c4,44(

c4/"char#n(

sH3/c4(

6S$stem.out.println"0D-=GE@T-D STGI%> IS203sH#(

s.close"#(

66

6


83/91

O&TP&T:

SERER:

=21jd,4.H1bin7java eser

-%T-G A STGI%>2the server

-%T-G T!- Q-E2

-%=GE@T-D STGI%> IS2 $mjYjw)jw

CLIENT:

=21jd,4.H1bin7java ecli

G-=-IR-D S>2 $mjYjw)jw

-%T-G T!- Q-E2

D-=GE@T-D STGI%> IS2 ]the server

RES&LT:

Thus the java program implementing the process of ,ry


84/91

AIM:

To stud$ the IEEE 580! Proto,o9.

IEEE 580! Proto,o9:

The I---


85/91

-ach -therneteFuipped computer operates independentl$ of all other stations on the networ,2

there is no central controller. All stations attached to an -thernet are connected to a shared

signaling s$stemB also called the medium. To send data a station first listens to the channelB andwhen the channel is idle the station transmits its data in the form of an -thernet frameB or pac,et.

After each frame transmissionB all stations on the networ, must contend eFuall$ for the netframe transmission opportunit$. Access to the shared channel is determined b$ the medium

access control "A=# mechanism embedded in the -thernet interface located in each station.The medium access control mechanism is based on a s$stem called =arrier Sense ultiple

Access with =ollision Detection "=SA9=D#.

As each -thernet frame is sent onto the shared signal channelB all -thernet interfaces loo, at thedestination address. If the destination address of the frame matches with the interface addressB

the frame will be read entirel$ and be delivered to the networ,ing software running on that

computer. All other networ, interfaces will stop reading the frame when the$ discover that the

destination address does not match their own address.

Mhen it comes to how signals flow over the set of media segments that ma,e up an -thernet

s$stemB it helps to understand the topolog$ of the s$stem. The signal topolog$ of the -thernet is

also ,nown as the logical topolog$B to distinguish it from the actual ph$sical la$out of the media

cables. The logical topolog$ of an -thernet provides a single channel "or bus# that carries-thernet signals to all stations.

Ma6.m-m Tra*sfer Rate:

The aimum Data Transfer Gate for I--- bps -thernet "I---


86/91

@reamble "@G-# X b$tes. The @G- is an alternating pattern of ones and ?eros that tells

receiving stations that a frame is comingB and that provides a means to s$nchroni?e the

framereception portions of receiving ph$sical la$ers with the incoming bit stream. Startofframe delimiter "SD# 4 b$te. The SC is an alternating pattern of ones and

?erosB ending with two consecutive 4bits indicating that the net bit is the leftmost bit

in the leftmost b$te of the destination address.

Destination address "DA# ; b$tes. The DA field identifies which station"s# should

receive the frame.

Source addresses "SA# ; b$tes. The SA field identifies the sending station.

ength9T$pe 8 b$tes. This field indicates either the number of A=client data b$tes

that are contained in the data field of the frameB or the frame t$pe ID if the frame is

assembled using an optional format.

Data Is a seFuence of n b$tes ";/N n /N4O55# of an$ value. "The total frame minimum

is ;b$tes.#

rame chec, seFuence "=S# b$tes. This seFuence contains a H8bit c$clic redundanc$

chec, "=G=# valueB which is created b$ the sending A= and is recalculated b$ thereceiving A= to chec, for damaged frames.

Note:

ultiple -thernet segments can be lin,ed together to form a larger -thernet A% using a signal

amplif$ing and retiming device called a repeater. Through the use of repeatersB a given -thernets$stem of multiple segments can grow as a 0nonrooted branching tree.0 _`%onrooted0 means

that the resulting s$stem of lin,ed segments ma$ grow in an$ directionB and does not have a

specific root segment. ost importantl$B segments must never be connected in a loop. -ver$segment in the s$stem must have two endsB since the -thernet s$stem will not operate correctl$

in the presence of loop paths.

-ven though the media segments ma$ be ph$sicall$ connected in a star patternB with multiple

segments attached to a repeaterB the logical topolog$ is still that of a single -thernet channel that

carries signals to all stations


87/91

EX0NO:1%: ST&D) OF 3E) DISTRI;&TION AND CERTIFICATION SCHEMES

AIM:

To stud$ the ,e$ d.str.2-t.o* a*d ,ert.f.,at.o* s,hemes

3E) DISTRI;&TION AND CERTIFICATION2

@ublic ,e$ encr$ption has its own difficultiesB in particular theproblem of obtaining someone^s true public ,e$. &oth of these problemsdetermining a shared

,e$ for s$mmetric ,e$ cr$ptograph$ and securel$ obtaining the public ,e$ for public ,e$

cr$ptograph$can be solved using atr-sted .*termed.ary0or s$mmetric ,e$ cr$ptograph$B the

trusted intermediar$ is called a ey d.str.2-t.o* ,e*ter "QD=#B which is a singleB trusted

networ, entit$ with whom one has established a shared secret ,e$. Me will see that one can use

the QD= to obtain the shared ,e$s needed to communicate securel$ with allother networ,

entitiesB avoiding some of the pitfalls we uncovered in. or public ,e$ cr$ptograph$B the trusted

intermediar$ is called a ,ert.f.,at.o* a-thor.ty ?CA@0A certification authorit$ certifies that a

public ,e$ belongs to a particular entit$ "a person or a networ, entit$#. or a certified public ,e$B

if one can safel$ trust the =A that certified the ,e$B then one can be sure about to whom thepublic ,e$ belongs. Cnce a public ,e$ is certifiedB then it can be distributed from just about

an$whereB including a public ,e$ serverB a personal Meb pageB or a dis,ette.

THE 3E) DISTRI;&TION CENTER:

Suppose once again that &ob and Alice want to communicate using s$mmetric ,e$ cr$ptograph$.

The$ have never met "perhaps the$ just met in an online chat room# and thus have not

established a shared secret ,e$ in advance. !ow can the$ now agree on a secret ,e$B given that

the$ can communicate with each other onl$ over the networ, A solution often adopted inpractice is to use a trusted ,e$ distribution center.

The QD= is a server that shares a different secret s$mmetric ,e$ with each registered user. This

,e$ might be manuall$ installed at the server when a user first registers. The QD= ,nows thesecret ,e$ of each userB and each user can communicate securel$ with the QD= using this ,e$.

et^s see how ,nowledge of this one ,e$ allows a user to securel$ obtain a ,e$ for

communicating with an$ other registered user. Suppose that Alice and &ob are users of the QD=(


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the$ onl$ ,now their individual ,e$BKA-KDCandKB-KDCB respectivel$B for communicating securel$

with the QD=.

4. UsingKA-KDCto encr$pt her communication with the QD=B Alice sends a message to the

QD= sa$ing she "A# wants to communicate with &ob "B#. Me denote this messageBKA-

KDC"ABB#.

8. The QD=B ,nowingKA-KDCB decr$ptsKA-KDC"ABB#. The QD= then generates a randomnumberBR1. This is the shared ,e$ value that Alice and &ob will use to perform

s$mmetric encr$ption when the$ communicate with each other. This ,e$ is referred to as

a o*e't.me sess.o* eyas Alice and &ob will use this ,e$ for onl$ this one session thatthe$ are currentl$ setting up. The QD= now needs to inform Alice and &ob of the value

ofR1. The QD= thus sends bac, a message to AliceB encr$pted using KAKDCB containing

the following2

R1B the onetime session ,e$ that Alice and &ob will use to communicate.

A pair of values2AB andR1B encr$pted b$ the QD= using &ob^s ,e$BKBKDC. Me

denote thisKBKDC"ABR1#. It is important to note that QD= is sending Alice not

onl$ the value ofR1for her own useB but also an encr$pted version of R1and

Alice^s nameB encr$pted using &ob^s ,e$. Alice can^t decr$pt this pair of values inthe message "she doesn^t ,now &ob^s encr$ption ,e$#B but then she doesn^t reall$

need to. Me^ll see shortl$ that Alice will simpl$ forward this encr$pted pair of

values to &ob "who can decr$pt them#.

These items are put into a message and encr$pted using Alice^s shared ,e$. The

message from the QD= to Alice is thusKAKDC"R1BKBKDC"R1##.

H. Alice receives the message from the QD=B etractsR1from the message and saves it.

Alice now ,nows the onetime session ,e$BR1. Alice also etractsKBKDC"ABR1# andforwards this to &ob.

. &ob decr$pts the received messageBKBKDC"ABR1#B usingKBKDCand etractsAandR1. &ob

now ,nows the onetime session ,e$BR1B and the person with whom he is sharing this,e$BA. Cf courseB he ta,es care to authenticate Alice usingR1before proceeding an$

further.

P&;LIC 3E) CERTIFICATION:

Cne of the principle features of public ,e$ encr$ption is that it is possible for two entities

to echange secret messages without having to echange secret ,e$s. or eampleB when Alicewants to send a secret message to &obB she simpl$ encr$pts the message with &ob^s public ,e$

and sends the encr$pted message to &ob( she doesn^t need to ,now &ob^s secret "that isB private#


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,e$B nor does &ob need to ,now her secret ,e$. ThusB public ,e$ cr$ptograph$ obviates the need

for QD= infrastructureB such as Qerberos.

Cf courseB with public ,e$ encr$ptionB the communicating entities still have to echangepublic ,e$s. A user can ma,e its public ,e$ publicl$ available in man$ wa$sB for eampleB b$

posting the ,e$ on the user^s personal Meb pageB placing the ,e$ in a public ,e$ serverB or b$

sending the ,e$ to a correspondent b$ email. A Meb commerce site can place its public ,e$ onits server in a manner such that browsers automaticall$ download the public ,e$ when

connecting to the site. Gouters can place their public ,e$s on public ,e$ serversB thereb$

allowing other networ, entities to retrieve them.

&inding a public ,e$ to a particular entit$ is t$picall$ done b$ a ,ert.f.,at.o* a-thor.ty"=A#Bwhose job it is to validate identities and issue certificates. A =A has the following roles2

1. A =A verifies that an entit$ "a personB a routerB and so on# is who it sa$s it is. There are

no mandated procedures for how certification is done. Mhen dealing with a =AB one must

trust the =A to have performed a suitabl$ rigorous identit$ verification. or eampleB if

Trud$ were able to wal, into the l$b$%ight certificate authorit$ and simpl$ announce0I am Alice0 and receive certificates associated with the identit$ of 0AliceB0 then one

shouldn^t put much faith in public ,e$s certified b$ the l$b$%ight certificate authorit$.Cn the other handB one might "or might notP# be more willing to trust a =A that is part of

a federalor statesponsored program "for eampleB *Utah 4:::+#. Cne can trust the

0identit$0 associated with a public ,e$ onl$ to the etent that one can trust a =A and itsidentit$verification techniFues. Mhat a tangled web of trust we spinP

8. Cnce the =A verifies the identit$ of the entit$B the =A creates a ,ert.f.,atethat binds the

public ,e$ of the identit$ to the identit$. The certificate contains the public ,e$ and

globall$ uniFue identif$ing information about the owner of the public ,e$ "for eampleB ahuman name or an I@ address#. The certificate is digitall$ signed b$ the =A.

3. et us now see how certificates can be used to combat pi??aordering pran,stersB li,eTrud$B and other undesirables. Mhen Alice receives &ob^s orderB she gets &ob^s

certificateB which ma$ be on his Meb pageB in an email messageB or in a certificate

server. Alice uses the =A^s public ,e$ to verif$ that the public ,e$ in the certificate isindeed &ob^s. If we assume that the public ,e$ of the =A itself is ,nown to all "for

eampleB it could be published in a trustedB publicB and well,nown placeB such as The

New York Times,so that it is ,nown to all and cannot be spoofed#B then Alice can be surethat she is indeed dealing with &ob. Illustrates the steps involved in =Amediated public

,e$ encr$ption.

4. &oth the International Telecommunication Union "ITU# and the I-T have developed

standards for certification authorities. ITU K.O5: *ITU 4::H+ specifies an authenticationservice as well as a specific s$nta for certificates. G= 488 describes =Abased ,e$

management for use with secure Internet email. It is compatible with K.O5: but goesbe$ond K.O5: b$ establishing procedures and conventions for a ,e$ management

architecture. Table describes some of the important fields in a certificate.
http://occ.awlonline.com/bookbind/pubbooks/kurose-ross1/chapter8/custom10/deluxe-content.html#utah1999http://occ.awlonline.com/bookbind/pubbooks/kurose-ross1/chapter8/custom10/deluxe-content.html#itu1993http://occ.awlonline.com/bookbind/pubbooks/kurose-ross1/chapter8/custom10/deluxe-content.html#itu1993http://occ.awlonline.com/bookbind/pubbooks/kurose-ross1/chapter8/custom10/deluxe-content.html#utah1999


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Selected fields in a K.O5: and G= 488 public ,e$ certificate

F.e9d Name Des,r.


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RES&LT:

Thus ey d.str.2-t.o* a*d ,ert.f.,at.o* s,hemeswere studied successfull$.

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