shivkumar_koppad_14043513_ee6093_final ecopy submission

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SUBMITTED AS PART OF

M.ENG INFORMATION AND NETWORK SECURITY

THESIS

Android Chat Application for secured communication

Author: Supervisor:

Shivakumar koppad Dr.Thomas Newe

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Declaration

I declare that this thesis is the result of my own research except as cited in the references. This

thesis has not been submitted in candidature of any other award in any other third level

institution.

Signed : _____________________________

Date : _____________________________

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Acknowledgement

This study wouldn’t have been possible without the constant love, motivation and support of many

people during the journey of my life.

Firstly to my supervisor Dr.Thomas newe for being there always on the side sharing his expertise,

knowledge and motivating me to improvise during the academic year 2014-2015.Definetly he is

one among the very few whom I admire to get inspired with every fresh breath on every sunrise.

To my friends from across the boundaries covering more than half of the globe during my time at

University of Limerick by adding the required vigour, confidence and for being such sport during

all the times especially for person who started his carrier and spent 18 Years of life at very small

town in the north of Karnataka, India.

Nevertheless to My parents and sister who have supported and inspired me to go one step further

during all the difficult times in the roller coaster of life and inspiring me to change the world we

perceive by being the change what self-thrusts for.

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Abstract

The goal of the thesis is to develop android chat application using eclipse for secured

communication which is compatible to all the versions of android 2.2 and above. Humans work

in collective level along with thought process and speech to convey as there standout

functionalities when compared to other living inhabitants of this planet. With the technology in

everyday life of all the people in 21st century instant chat messaging brings people together from

across the demographic locations and security is as crucial as the communication between two

entities because of the attacks and new vulnerabilities which pops up every new day. Android

being popular and most reliable open source operating system for smartphones with more than

1/6 th of user database in the world, Secured chat communication for such OS will not only make

it more trusted but also helps in elevating humans affinity towards technology. Different security

algorithms such as DES,AES,RSA are used for encryption while sending the data , received text

will be in the form of ciphers at the receivers inbox which will get decrypted once the user wants

to decrypt by copying the contents in the decryption tab.

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Contents

Table of Figures ............................................................................................................................................. 7

Introduction .................................................................................................................................................. 8

Chapter 2 - Cryptography.............................................................................................................................. 9

2.1.1 Background of cryptography. ....................................................................................................... 9

2.1.2 Cryptography ............................................................................................................................... 9

2.1.3 The four building blocks of efficient cryptography are .............................................................. 10

2.2.1 Vulnerabilities and Exploits. ....................................................................................................... 10

2.2.2 Common Vulnerabilities............................................................................................................. 10

2.3 Common attacks. .............................................................................................................................. 11

2.3.1 Brute force attack – ................................................................................................................... 11

2.3.2 Dictionary attacks – .................................................................................................................... 12

2.3.3 Denial of service attack – ........................................................................................................... 12

Chapter 3 ..................................................................................................................................................... 14

Security algorithms and key exchange. .................................................................................................. 14

3.1 Deffiei-hellman ................................................................................................................................. 14

3.2.RSA .................................................................................................................................................... 17

3.3 DES (Data Encryption Standard) algorithm ....................................................................................... 19

3.4 AES (Advanced Encryption Standard) ............................................................................................... 21

3.5 MD5 ................................................................................................................................................... 22

Chapter 4 - Android and chat application ................................................................................................... 23

4.1 History of Android. ............................................................................................................................ 23

4.2 Below are the different android versions and most of them are named after desserts. ................. 23

4.3 The different tools which android as operating system support for the smartphones are ............. 24

4.4 Requirements for android on Hardware level. ................................................................................. 26

4.5 Android for chat application ............................................................................................................. 26

4.5.1 Whats app – ............................................................................................................................... 26

4.5.2 Viber- .......................................................................................................................................... 27

4.5.3 Send – ......................................................................................................................................... 28

4.5.4 Blackberry Messenger – ............................................................................................................. 28

4.5.5 Facebook Messenger ................................................................................................................. 28

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4.5.6 Skype – ....................................................................................................................................... 29

Chapter5.0 - Application framework and outlook ...................................................................................... 29

5.1 The following show the architecture of security implementation in secure messaging. ................. 29

5.2 User Interface Description ................................................................................................................ 30

5.3 Use Case Diagram ............................................................................................................................. 35

5.4 Data flow diagram ............................................................................................................................. 36

Chapter 6. .................................................................................................................................................... 37

Application design and architecture. .......................................................................................................... 37

6.0 Integration of JAVA and CRYPTOGRAPHY ......................................................................................... 37

6.1 JCA Architecture .......................................................................................................................... 38

6.2 JCE ............................................................................................................................................... 39

6.3 Engine Classes ............................................................................................................................. 39

6.3.1 JCA Engines ......................................................................................................................... 39

6.3.2 JCA Engines ......................................................................................................................... 40

6.4 Security protocol ............................................................................................................................... 41

Chapter 7.0 .................................................................................................................................................. 42

Implementation of Security: ....................................................................................................................... 42

7.1 RSA Algorithm: .................................................................................................................................. 42

7.2 DES Algorithm: .................................................................................................................................. 44

7.3 AES Algorithm: .................................................................................................................................. 47

7.4 Secure MD5 Hashing: ........................................................................................................................ 49

Chapter 8.0 Testing and result .................................................................................................................... 51

References .................................................................................................................................................. 52

Appendix ..................................................................................................................................................... 54

AESHelper.java ........................................................................................................................................ 54

DESHelper.Java ....................................................................................................................................... 56

Encryptmessage.java .............................................................................................................................. 59

Mainactivity.Java..................................................................................................................................... 61

RSAhelper.Java ........................................................................................................................................ 65

Showmsg.java ......................................................................................................................................... 67

SMSreceiver ............................................................................................................................................ 68

Splashscreenactivity.Java ........................................................................................................................ 70

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Table of Figures

Figure 1.Encryption and Decryption of Cryptography. ............................................................................... 10

Figure 2.Denial of service attacks. .............................................................................................................. 13

Figure 3.Diffie Hellman key exchange. ........................................................................................................ 15

Figure 4.Mathematical computation of Diffie hellman .............................................................................. 16

Figure 5.RSA Encryption and Decryption. ................................................................................................... 18

Figure 6.DES algorithm ................................................................................................................................ 20

Figure 7.AES Input. ...................................................................................................................................... 21

Figure 8.Various flavours of Android. ......................................................................................................... 23

Figure 9.Growth of messaging application whats app ................................................................................ 27

Figure 10.Microsoft line .............................................................................................................................. 28

Figure 11.Security implementation in instant messaging........................................................................... 29

Figure 12.Welcome screen of application. ................................................................................................. 30

Figure 13.Option to choose between simple and secure texting. .............................................................. 31

Figure 14.Choosing the number from the contact list to send the message. ............................................ 32

Figure 15.Encryption before sending. ......................................................................................................... 33

Figure 16.Decryption of Message at the receiver side. .............................................................................. 34

Figure 17.Use case diagram. ....................................................................................................................... 35

Figure 18: JCA Architecture ....................................................................................................................... 38

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Introduction

As the world is evolving the need for communication between the people is rising. The extreme

demand is for instant communication is leading the IT developers to come up with new means of

communication which are faster and available widely. In 21st century internet is considered as

fastest means of communication, why not ? We can send and receive information from every

corner of this planet. Considering the flexibility of internet the service providers are leaning

towards it and coming up new products for communication. Among all the application Android

based applications are appreciated the most. There are many android applications in the market

which provide communication. Providing just communication is not enough on insecure network,

enabling strong security is important as well. The proposed application strikes perfect balance

between security and integrity. The application provides instant communication and at the same

time strong security. Users are allowed to select the security they want and exchange the messages.

The encryption algorithms used in the application are RSA, AES, DES and Deffiei-Hellman.

The message may contain sensitive information that no one should get access to apart from

authorized users. Encrypting the messages before sending over insecure network is important.

RSA is one of the top rated asymmetric encryption algorithm that has been used in the application.

Public key which is available for the sender is used to encrypt the messages and private key is kept

secret by the receiver for decryption. The above mentioned algorithm can strengthen the security

so that no unauthorized entity can learn the information that is being transferred. While sending

the public key by the destination to the sender, anyone can learn it and make use to decrypt the

secret messages. To relent this risk Deffiei-Hellman key exchange algorithm is used. Using this

algorithm two authorized entities can exchange the keys without the knowledge of eavesdropper.

As of now we have secured the message as well as the key from unauthorized entity, but anyone

can alter the encrypted data passing via insecure network. To address this risk MD5 hashing

algorithm has been used using which we can analyze whether the message has been altered. Adding

to that used is allowed to select which algorithm user want to encrypt his/her data. To make this

happen AES and DES algorithm are made available.

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Chapter 2 - Cryptography

2.1.1 Background of cryptography.

Cryptography is one of the oldest fields of technical study having history of more than 4000 Years. (Cohen,

1990-1995)With the advancement of technology in the 21st century, the need for secured communication

has become vital in order to secure the data while channelizing between two entities. Though the idea of

cryptography has been existed since ages specially to hide the data from enemies in wars and used by

Julius ceaser which was termed as mono-alphabetic substitution ciphers .The idea of cryptography in the

world of internet has seen exponential growth since last several decades when people started using

Internet for transmission of crucial credit card ,debit card details, personal information in all walks of life

in everyday life .Cryptography across the internet is basically applying complex computational

mathematics and logic to adhere to the protocols and server its basic purpose. The key factors which

determine elegant cryptographic implementation are Data confidentiality,Integrity,Availibility,non-

repudiation,authorization.While all the multinationals organizations with billion plus dollars in revenues

containing the information of billion people cryptography becomes vital.

2.1.2 Cryptography

Cryptography is art of science which deals with secret writing of data. It involves method of secret writing

where plane text is converted to encrypted text using cipher and is termed as Encryption. Reverse process

of data where cipher text is converted to plain text is termed as decryption. It should be hard to recover

the messages from the ciphertext when the messages are drawn from arbitrary probability distributions

defined on the set of all strings (i.e arbitrary message spaces). (Shafi Goldwasser, July 2008)

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Figure 1.Encryption and Decryption of Cryptography.

2.1.3 The four building blocks of efficient cryptography are

1. Confidentiality – Its service which states that no one should be able to read the data except the intended

entity.

2. Integrity – Data sent from sender shouldn’t be modified or hampered while its been received at the

receiver side.

3. Authentication – Data should be authenticated where receiver is assured of sender’s identity.

4. Non-repudiation – Its protocol where sender cannot deny of the fact later of not sending the data and

receiver cannot deny of the fact of not receiving the data. Proof of origin and proof of reception is taken

care of.

2.2.1 Vulnerabilities and Exploits.

Any flaw in the application, code or software is termed as vulnerability and usage of vulnerability by the

attacker in order to perform illegitimate actions is coined as Exploits.

2.2.2 Common Vulnerabilities.

2.2.2.1. Injection Flaws – Happens when unfiltered data is injected to Sql server, browser or the LDAP

Server .The problem is attacker can inject the command henceforth malicious content once he has

access resulting in loss of data and controlling client’s browsers. (wichers, 2013)

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Prevention – By filtering and verifying all the data which is been received without giving room for any

input to enter henceforth inject the malicious execution.

2.2.2.2.Broken authentication – When the authentication is broken ,the url might contain the session Id

and leak it in the reference header to others, the password might not be encrypted either in storage or

transit, session id’s might be predictable ,session hijacking when timeouts not implemented right or using

HTTP. (wichers, 2013)

Prevention – By using framework and educating oneself on what pitfalls are.

2.2.2.3.Cross site scripting – This happens because of widespread input sanitization failure where

attacker give tags to web application java script and when its being executed when input is returned to

user unsanitized. Which will further paves path by giving information about cookies to the attacker.

Prevention – By preventing Html tags not to return to the client. (wichers, 2013)

2.2.2.4. Insecure direct object reference – This happens by trusting user input and paying the price in

resulting security vulnerability. Direct object reference means when internal object such as file or data

base key is exposed to the user and attacker can provide reference and if authorization is not enforced

attacker can access or do things that they should be precluded from. (wichers, 2013)

Prevention – By performing user authorization properly and consistently therefore whitelisting the

choices.

2.3 Common attacks.

2.3.1 Brute force attack – Brute force attack is trial and error method used to obtain information

such as user password or personal identification number. It executes by trying out all the combinations of

password inorder to crack. It is also used by security analyst to check the organizational network security.

Prevention.

1. By using strong passwords.

2. with the help of access control while logging in.

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3. by locking out the users who exceeds the maximum login attempts.

2.3.2 Dictionary attacks – It is method of breaking into password protected system logically by

entering all the possible combination of all the words in dictionary as a password. These dictionaries

include a diverse collection of usernames and passwords and may simply represent a conglomeration of

smaller dictionaries. The root account and various system accounts are well represented, with passwords

of varying types including common English words, proper names, keyboard patterns, and “leets,” which

replace letters with numbers or symbols that resemble the replaced letter. (matthews, 2007) It can also

be used to find the key which Is used for encryption and decryption. Often used by spammers, message

is sent to email address consisting of words and phrases followed by @symbol.

Prevention.

Can be reduced to near zero by limiting the number of attempts allowed within given amount of time and

by wisely choosing the password key. For illustration, only three attempts are allowed then gap of 15

minutes before attempting for the fourth time

2.3.3 Denial of service attack – Prevent the service being used by others by overloading

resources. When multiple host attack simultaneously is DDOS attack. It is executed by sending fake

requests to web server henceforth by increasing the load on the server. DoS attacks in the Internet

generally conquer the target by exhausting its resources that can be anything related to network

computing and service performance, such as link bandwidth, TCP connection buffers, application/service

buffer, CPU cycles, etc. (Qijun Gu) Individual attackers can also exploit vulnerability, break into target

servers, and then bring down services. Hackers have been carrying out the Denial of service attack from

decade starting from 500 MB in 2002 to 10+ GB by 2015.Flash crowd is generic term used to phrase the

huge traffic on webservers.

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Figure 2.Denial of service attacks.

2.2.3.1 Aims of DDOS attacks.

Consuming bandwidths with large traffic volumes, Overload or crash the network handling service,

sending specific type of packets in order to consume targeted available resources.

2.2.3.2 Prevention of Dos attacks.

Attack prevention and preemption before the attack, detection and filtering during the attack, source

trace back and identification after the attack. Multiple firewalls will enable to stop the flooding attacks,

Switches provide system wide rating, traffic shaping, delayed binding to detect and remediate denial of

service attacks. By adding rules to take out flow statistics during Dos attacks they further slowdown and

complicate the attack.

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Chapter 3

Security algorithms and key exchange.

3.1 Deffiei-hellman

First public-key type scheme proposed by Diffie & Hellman in 1976 along with the exposition of public key

concepts. (stallings) In secure message exchange system usage of encryption algorithm is quite

common which leads to data security over an unsecure network. The multiple parties participating

in information exchange has to exchange their encryption/decryption key with each other so that

the data encrypted by one can be decrypted by the authorized party. During the key exchange, an

eavesdropper (passive attack) can capture the key that is being exchanged between the authorized

parties and decrypt the information. To address this vulnerability we require a secure way for key

exchange. Deffiei-hellman algorithm provide a secure method of key exchange where the users

involved in the conversation can exchange their keys in the presence of attacker. Both the parties

agree on a common key which is used to encrypt the public key. Let’s analyze how the authorized

parties agree on same key without revealing it over the unsecured network.

Let’s start with the general example for the sake understanding, consider Alice and Bob, two

parties who are willing to agree on a key.

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Figure 3.Diffie Hellman key exchange.

Bob and Alice agrees on one common paint (C) which an attacked can know about.

Bob and Alice pick one secrete color of paint, B and A respectively, which they don’t share

with each other.

Both the parties will mix their secrete paint with the common paint they agreed on. Now

Alice have AC and Bob have BC as mixed color.

Now both the parties exchange their mix paint with each other. Alice has BC and A, Bob

has AC and B.

Both the parties will mix their secrete color with the mixed color received from the other

party. So, Alice got ABC and Bob got ABC.

Now both the authorized partied have same color.

The eavesdropper cannot learn the common paint both the authorized parties agreed on as

he/she don’t know the secrete color that has been mixed with the common color.

Now let’s analyze how we can represent this method mathematically so that we can use it in real

time.

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Figure 4.Mathematical computation of Diffie hellman

Alice and Bob agree on one prime number P and one generator G in plain text such that

P>G and G is primitive root of P.

P=11 and G=7.

Now Alice and Bob generate one random secrete number each.

Alice’s Secrete number XA=6.

Bob’s secrete number XB=9.

Both parties use the formula Y = GX mod P.

Alice: Ya = GXa mod P

YA = 76 mod 11 = 4.

Bob: YB = GXb mod P

YB = 79 mod 11 = 8.

Now Alice and Bob exchange YA and YB with each other with is in plain text.

Now both the parties can use their secrete integer and the integer received from each other.

Required Secrete number, SK = YX mod P.

Alice: SK = (YB)XA mod P.

SK = 86 mod 11 = 3

Bob: SK = (YA)XB mod P.

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SK = 49 mod 11 = 3

Now, Both Alice and Bob got same Secrete Key which they can use to encrypt/decrypt the

key required to encrypt/decrypt the actual information.

Clearly, much larger values of a, b, and p are required. An eavesdropper cannot discover this

value even if she knows p and g and can obtain each of the messages. Suppose p is a prime of

around 300 digits, and XA and XB at least 100 digits each. Discovering the shared secret key would

take longer than the lifetime of the universe, using the best known algorithm. This is called the

discrete logarithm problem.

3.2.RSA

RSA algorithm was invented in 1977 by three scientists, namely, Ron Rivest, Adi Shamir and Len

Adleman. RSA is asymmetric encryption algorithm where two keys are generated, namely, public

key and private key. (scarvalone, 2009) The encryption of required plain text is done using public

key and the cypher text can be converted back to plain text using private key. Both the keys are

inversely proportional to each other. RSA can be used both for encryption and digital signatures.

RSA serves many protocols like SSH, SSL/TLS, S/MIME and OpenPGP. RSA derives its keys by

multiplying two large prime numbers, Rabin-Miller primality test algorithm is used to generate

prime numbers for RSA. Determining the prime numbers used from the product is extremely

difficult and time consuming even using super computers. The strength of encryption depends on

the length of public key. The keys are typically 1024 to 2048 bits long. Previously keys of length

1024 were used but as the technology developing at a rapid rate we can expect the key to be broken

at any time in near future. So the industries are switching towards keys with the length 2048 bits.

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Figure 5.RSA Encryption and Decryption.

The party willing to receive encrypted information from authorized source will generate two keys,

namely, public key and private key. Both the keys are inversely proportional to each other. The

public key is sent to the authorized source over the unsecured using deffiei-hellman algorithm and

the privet key is kept secrete. Whenever the source want to send the information to destination, it

uses the public key of destination to encrypt the information using the formula provided by the

RSA algorithm. The genuine destination can decrypt the cyphertext using the unshared private

key.

Lets see how RSA encryption algorithm works,

Algorithm:

Generation of two prime numbers:

Consider p and q as two prime number, compute n=pq.

Calculate φ(n)

φ(n)=(p-1)(q-1)

We need an exponent e, provided

It is an integer

Not be factor of n

1 < e < φ(n)

The public key is made up of two numbers that is e and n.

The private key is computed by the following steps

Private key, d =( 2(φ(n))+1 ) / e

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Encryption of information m can be done using the following formula,

c= me mod n.

Decryption of the cyphertext c can be decrypted by private key d using the following

formula,

m= cd mod n.

Example:

Generation of two prime number p and q, and n.

Consider p=53 and q=59

Compute n=pq i.e. n= 53*59 = 3127

φ(n)= (p-1)(q-1) = (53-1)(59-1) = 3016

Consider e = 3

Public key is (n,e)

Public key = (3127,3)

Private key,

d= ( 2(φ(n)) + 1 ) / e

d= ( 2(3016) + 1 ) / 3

d=2011

Now we can encrypt the information using the public key (n,e) that is (3127,3)

Lets consider the information as m=89, so the encrypted information c is,

c= 893 mod 3127 = 1394

The cypher text c= 1394 can be decrypted using the private key,

m= cd mod n = 13942011 mod 1327 = 89

3.3 DES (Data Encryption Standard) algorithm

DES is symmetric key algorithm used to encrypt/decrypt the information that has to secured from

unauthorized entity over the unsafe network. DES was developed at IBM in early 1970s based on

the design of Horst Feistel. In those days the algorithm is considered as one of the strongest

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encryption algorithm and selected by National Bureau of Standards as an official FIPS (Federal

Information Processing Standard) of United States in 1977. DES uses 56bit key and can encrypt

64bits of plain text at a time. (Daley, 1999)

Figure 6.DES algorithm

DES algorithm uses its 56bit key to encrypt the given plain text into 64bit enciphered blocks by

means of permutation and substitutions. The process takes place in 16 rounds. Each plain text can

be encrypted individually or making the present block of information dependent on the previous

blocks. Decryption is reverse process of encryption. The same 64 bit key used in encryption is

applied to the cipher while performing decryption.

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3.4 AES (Advanced Encryption Standard)

AES encryption algorithm is extended version of DES encryption algorithm. AES is a block

cipher. This means that the number of bytes that it encrypts is fixed. AES has 3 ciphers AES-128,

AES-192 and AES-256. The plain text of block size 128bits can be encrypted/decrypted using any

of the 126, 192 and 256 bit keys. AES uses same key for encryption as well as decryption. So the

source and destination must know the secrete key that has been used. The level of security depends

on the key length. (Federal information processing standards publications., November 26,2001)

The higher the key length, higher the security level. Depending on the key length the encryption

rounds increases. There are 10, 12, and 14 rounds of encryption is performed for the key length

128, 192 and 256 bit respectively.

Figure 7.AES Input.

Each round will consist of four processes, namely, SubByte, ShiftRows, MixColumns and

AddRoundKey. Internally the AES algorithm’s operations are performed on 2 dimension array of

bytes called states. AES algorithm process the data in Hexadecimal units.

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3.5 MD5 (Message Digest 5)

MD5 is hashing algorithm used maintain integrity designed by Ron Rivest in 1991. MD5 is one

way encryption where it is extremely difficult to generate plain text from the cipher text. It can be

used for digital fingerprints and secure password storage. (Kozushko, 11/28/2003)

MD5 algorithm consists of 5 steps

Step 1: The original message is padded with required amount to bits to make the size of the data

block congruent to 448 modulo 512. We must follow the following rules while padding the

required amount of bits to the original message. The rules are as follows,

Firstly, the message is padded with the bit 1.

To bring the message length to 64 bits fewer than a multiple of 512 we should add required

amount of 0s following 1.

Step 2: Append length. A 64bit representation of the actual message is appended to the result of

previous step. The output of this step has a length that is an multiple of 512 bits.

Step 3: Now initialize the Message Digest buffer. The buffer is divided into 4 parts, namely A, B,

C and D, each of 32bit length. Word A, B, C and D are initialized to the initial value 0x67452301,

0xEFCDAB89, 0x98BADCFE, 0x10325476 respectively.

Step 4: Process message in 16 word block i.e., 512 bit block. In this step we append the message

in blocks of 512 bits each. For each input block, 4 rounds of operations are performed with 16

operations in each round.

Step 5: This is the last step used to output the content of the four words i.e. A, B, C and D. The

output will be in low order byte first sequence.

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Chapter 4 - Android and chat application

4.1 History of Android.

Android took birth on November 2007 and November 5 has been regarded as birthday of Android

(spaight) and down the line 8 years it has been one of the most successful and powerful mobile operating

systems in the history of smartphones with more than billion users and billion plus android open source

applications in the android store. Android is currently under development by Google and Open handset

alliance since its first release.

4.2 Below are the different android versions and most of them are

named after desserts.

Figure 8.Various flavours of Android.

1. Cupcake 1.5

2. Donut 1.6

3. Éclair 2.0 - 2.1

4. Froyo 2.2- 2.3

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5. Gingerbird 2.3 – 2.3.7

6. Honeycomb 3.0 – 3.2.

7. Ice cream sandwich 4.0

8. Jellybean 4.1 – 4.3

9. Kitkat 4.4

10.Lollipop 5.0 – 5.1

11.Marshmallow

4.3 The different tools which android as operating system support for

the smartphones are

1. Gmail synchronization with application.

2. Contacts in line with people application.

3. Google maps and street view to find the different directions on various demographic locations using

GPS.

4. Voice speech recognition on Google talk.

5. Instant messaging, text messaging, Multimedia messaging, calculator, business applications, social

media applications like Facebook, Instagram, twitter, quora, viber. (DHT Technologies.)

6. Media player which runs the audio and visual files both in the background and at the user interface.

7. Search option where people can put the query to obtain any information over the internet.

8. Different notifications which arrive at the status bar with regards to setting the alarm, brightness of the

phone, email notifications, Instant messaging notifications.

9. Voice recognition dialer which enables user to dial the contact number without using manual input.

10. Wallpaper which accounts for the different images including personal ones on the background for

marvelous ambient approach.

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11. wi-fi and Bluetooth connections.

12. Video watching software’s such as YouTube.

13. Support for third party text prediction and dictionary for user usage.

14. Auto rotation of the screen.

15. Setting up the pictures for the contact list.

16. USB tethering and hotspot functionality where users can create own network and add different

devices to it.

17. Picture and video uploads on social networking sites.

18. Support for near field communication.

19. Power management which enables user to identify the applications which are consuming more power

and can halt them when they are not being actively used 24-7 thus improvising the battery life.

20. Video calling support using applications such as Skype to connect users from different parts of the

globe.

21. Holographic interface.

22. Multitasking where user can access different applications with one touch.

23. Encrypts all the user data using security protocols.

24. Connectivity for USB applications.

25. Provides excellent UI for gaming applications.

26. Adding additional storage on SD card where user can store huge bulk of data.

27. Able to excess Microsoft office thus making it more reliable for connectivity.

28. Keypad is available in multiple languages and user has the ease to select one of his choice.

29. Switching on to airplane mode when travelling beyond the earth’s atmosphere.

30. Facial recognition where device is unlocked once the pattern is matched.

31. Photo gallery is viewed in multiple outlooks for user experience.

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32. Can be supportable upto 64 bit processors.

33. Multiple login accounts for the email account as in single mail application can be used by more than

one user.

34. Flashlight drawn from the camera application can also be used as torch.

4.4 Requirements for android on Hardware level.

From the rediscovery of operating systems from android version 1.6 to android 5.0 the vital hardware

requirement is ARM architecture which also includes microprocessor without interlocked pipeline stages

which is reduced instruction set computer which varies from MIPS 1 to MIPS 6 and also x86 processors.

The minimum Ram requirements for the efficient execution of operating system has been varied over

time which started with minimum 32 MB RAM,32MB flash memory and 200 MHZ ARM architecture and

now has been extended up to 4 Gb OF RAM manifested by Qualcom,mediatek 230 MB flash memory 1

GHZ ARM architecture. (Wikipedia ,Free Encyclopedia., 2015)

4.5 Android for chat application

The best part of android chat application are they enable to send/receive the text,image,video between

two users across the globe without spending penny on telecommunication network. Provided the little

data charges which user has to account while using it.They are becoming increasingly popular in never

seen before rate in last several years due to the ease, reliability, productivity and user addiction over the

smartphone.

Whatsapp, Viber, Skype, Line, Wechat,facebook messenger are the frontiers in this field considering other

thousands of applications which make the demand get executed.

4.5.1 Whats app – Whats app as company started by former yahoo employee Brian Acton and Jan

korum in 2009 which works on subscription model consisting just over 50 Employees was acquired by

Facebook for whopping 19 billion US dollars which now has around 900 active users in the world. This is

the best example why instant messaging application is such at apex boom in the market of Information

27

technology. Easy setup, automatic synchronization with phone contacts,ad free experience ,automatic

synchronization with phone contacts makes the whats app best in the business which charges 0. 99USD

every year after free subscription for the first year.

Figure 9.Growth of messaging application whats app

4.5.2 Viber- The basic functionality of viber includes instant messaging, Pic sharing with added

emotions and sticker sharing. What makes viber one of the leading application in android store is its ability

to call to anyone on their phone without carrier charges for the telecommunication network which varies

with the location you are dialing with automatic synchronization of contacts and also letting to know

about the people who use Viber on their contact list. Viber is hassle free of pin input when user logs into

the app and uses telephone number as the input.

28

4.5.3 Send – Microsofts send is one of the other instant messaging app which stands out in with feature

of beginning instant messaging application on the email without the need for user to login in to Email

account everytime.Its highly recommended for the official trans/receive of information as its makes it

more quick, handy and saves lot of time user puts in during email communication.

Figure 10.Microsoft line

4.5.4 Blackberry Messenger – Thought Blackberry messenger was proprietary based application

which was restricted to black berry users which enables user to send/receive texts, images, videos,

location sharing, automatic voice recognition until it was released in 2013 on android store and IOS.A pin

system allows user to share BBM contacts without having to share phone or email details while the 2 way

opts in for communication allows user to control the text which are being received to the inbox.

4.5.5 Facebook Messenger – Facebook messenger is brought up by Social networking giant

Facebook. Where user contact list is automatically synchronized by the connections he/she has in their

friend list. Application enables to send/receive text, images, voice, Emotions, stickers, URL’s, files, folders

29

Figure 11.Security implementation in instant messaging.

etc. It’s quite handy when compared to other applications is of the fact that there is chat pop up on the

front end of the screen of the smartphone which user can use even when other applications are being

used. Facebook has introduced dialing facilities on the chat application where user can other people in

their friend list and even can do video chat. User can block the other persons profile when he/she doesn’t

want to receive any text/image/video/files from the users as sometimes malicious contents/spam are

being sent by unknown entities over the internet.

4.5.6 Skype – Besides being known for the video calling and send/receive of the short video

functionality ,skype does has strong instant messaging facilities in its application. With the help of skype

credits users can call to any part of the world to the people who are in there contact list. Though the vb

instant messaging facility isn’t that popular in day – day lives of the users but skype does provide ease and

reliability for the users to communicate

Chapter5.0 - Application framework and outlook

The proposed application is designed to send and receive encrypted text messages and

decrypt at the receiver side.

5.1 The following show the architecture of security implementation in

secure messaging.

Insecure Network

Sender/receiver

Sender/receiver

Messaging Messaging

Send/Receive Cypher text

30

5.2 User Interface Description

Application is designed using Android 4.0 using eclipse IDE, This application uses multiple

encryption and decryption algorithms to ensure secured message exchange.

1. The application starts with welcome screen which is as follows

5

2. Application consists of two types of texting options, one is plain texting, and another is

secure texting. As soon as the application opens we find the above figure and it takes us to

select the type of messaging activity whether secure texting or simple texting. The screen

is as follows

Figure 12.Welcome screen of application.

31

Figure 13.Option to choose between simple and secure texting.

32

3. If we select Simple texting we can make simple messages where there is no security for

outgoing messages Its just like normal messages. The following is the screen to show the

simple messages.

Figure 14.Choosing the number from the contact list to send the message.

33

4. If we select Secure Texting we can make secure messages where we are encrypting the

outgoint messages which different kinds of algorithms available in android. Namely AES,

DES, RSA

Figure 15.Encryption before sending.

34

5. And the main screen is having one more option called Decrypt Inbox messages which helps

you to decrypt the message which are already received in inbox.

Figure 16.Decryption of Message at the receiver side.

35

Figure 17.Use case diagram.

5.3 Use Case Diagram

Select Contact

Generate Random Number

Hash Random numbers

Generate Key with Hash Data

Use As Key for Selected Algo

Send Message

Select Algorithm

Sender

Receiver

36

5.4 Data flow diagram

Sender/

Reciever

Select Type

Simple

Secured Simple Text Secured Text

Select Contact

Select Algorithm

Send Message

Select Contact

Send Message

37

Chapter 6.

Application design and architecture.

6.0 Integration of JAVA and CRYPTOGRAPHY

The chat application is built on JAVA platform as it strongly emphasize on security. Cryptography

is integrated with Java to achieve secure communication. Java application can be developed using

either of the below library:

JCA and JCE APIs (Application programming interface).

JCA and JCE are the two main APIs which helps in Cryptographic operations(Oracle 2011).

By using these APIs Java provides the cryptographic functionality.

Java Cryptography Architecture (JCA)

- It is a security framework which is integrated with the core JAVA API

Java Cryptography Extension (JCE)

- This is the extension of JCA for strong encryption.

38

6.1 JCA Architecture

Figure 18: JCA Architecture

JCA/JCE provides the functionalities of various cryptographic services.

Cryptographic implementation is actually provided by service providers.

JCA/JCE is structured with “Engine” classes and these classes provide a standard interface

into the cryptographic service provides.

JCA provides two provider classes:

Provider (Cryptographic Service Provider): It has methods which are used to get

information about provider’s name and version number.

Security: It manages the installed service providers and security properties. Basically used

to add, remove or modify providers.

39

6.2 JCE

It provides many functions which JCA doesn’t provide such as encryption/decryption and

symmetric key generation.

It uses the provider class of JCA.

6.3 Engine Classes

They actually provide an interface for every specific cryptographic operation such as Digital

signature, Encryption, Message Digest etc.

Cryptographic operations are categorized into classes in JCA/JCE. These classes are named as

engines.

JCA Engines/Classes

JCE Engines/Classes

6.3.1 JCA Engines

MessageDigest: Produces hash value(MD5,SHA)

Signature: Produces digital signatures

– KeyPairGenerator: Produces pairs of keys

KeyFactory: breaks down a key

KeyStore: Manages and stores keys

SecureRandom: Produces random/pseudo-random numbers

– AlgorithmParameters: Maintains the security parameters for specific algorithms

– AlgorithmParameterGenerator: Creates parameters

CertificateFactory: Generate certificates and revocation

CertPathBuilder: Establishs relationship chains between certificates

CertStore: It stores certificates and revocation.

40

6.3.2 JCA Engines

Cipher: Encryption and Decryption

KeyGenerator: Produces secret keys used by ciphers for encryption/decrypton.

SecretKeyFactory: Operates on Secret Key objects

KeyAgreement: Key agreement protocol

MAC: Provides Message authentication code functionality

6.3.2.1 JCA/JCE Engine location:

JCA Engine: Located in java.security package

JCE Engine: Located in javax.crypto package

Example Codes(Oracle 2011):

1. Generating the key:

KeyGenerator keygen = KeyGenerator.getInstance("AES");

SecretKey aesKey = keygen.generateKey();

2. To generate the cipher object from the key generated above:

Cipher aesCipher;

// Create the cipher

aesCipher = Cipher.getInstance("AES/ECB/PKCS5Padding");

We use the generated aesKey from above to initialize the Cipher object for encryption:

// Initialize the cipher for encryption

aesCipher.init(Cipher.ENCRYPT_MODE, aesKey);

// Our cleartext

byte[] cleartext = "This is just an example".getBytes();

// Encrypt the cleartext

byte[] ciphertext = aesCipher.doFinal(cleartext);

// Initialize the same cipher for decryption

41

aesCipher.init(Cipher.DECRYPT_MODE, aesKey);

// Decrypt the ciphertext

byte[] cleartext1 = aesCipher.doFinal(ciphertext);

Plaintext Input:

Hello, Welcome to the world of Encryption and Decryption

Cipher Text Output:

07f7d720f351119ed651836585e40dea0d873f08223cf3f5fd1c81fbe42986eb1b1100b7133f75b2f

83800013dbd6bdb6d300497f605713540fe6003f53d7594

6.4 Security protocol

Here in the proposed system we designed a secure protocol to send text messages which can not

be broken by any hackers in the network the protocol is as follows

Here the protocol works at both the Sender and the Reciever

Step 1:

First the plain text is encrypted with RSA algorithm we are using big integer algorithm to

encrypt the message then encrypted message is taken out.

Step 2:

We are creating a 16 digit random numbers and random number will be hashed using secure

md5 hash algorithm

Step 3:

The RSA encrypted data is again encrypted with DES algorithm using hash data as a secure

key.

Step 4:

Here again DES encrypted data will be taken out and again encryped with AES algorithm

and the key is hash data. Then

42

Step 5:

Final Encrypted data is sent to the receiver and receiver side the algorithm information is

obtained using key term which is sent in the message along with secured data then using the key

term the application understand the type of algorithms used in the encryption based on the type of

key term decryption will be stated for the incoming message on demand and then final plain text

will be given to receiver.

Chapter 7.0

Implementation of Security:

The application works on several cryptographic functionalities using the supported types of

cryptography from android we designed a secure protocol to send and receive text messages.

7.1 RSA Algorithm:

public RSAHelper(int bits) {

bitlen = bits;

SecureRandom r = new SecureRandom();

BigInteger p = new BigInteger(bitlen / 2, 100, r);

BigInteger q = new BigInteger(bitlen / 2, 100, r);

n = p.multiply(q);

BigInteger m = (p.subtract(BigInteger.ONE)).multiply(q

.subtract(BigInteger.ONE));

e = new BigInteger("3");

while (m.gcd(e).intValue() > 1) {

e = e.add(new BigInteger("2"));

}

d = e.modInverse(m);

}

/** Encrypt the given plaintext message. */

43

public synchronized String encrypt(String message) {

return (new BigInteger(message.getBytes())).modPow(e, n).toString();

}

/** Encrypt the given plaintext message. */

public synchronized BigInteger encrypt(BigInteger message) {

return message.modPow(e, n);

}

/** Decrypt the given ciphertext message. */

public synchronized String decrypt(String message) {

return new String((new BigInteger(message)).modPow(d, n).toByteArray());

}

/** Decrypt the given ciphertext message. */

public synchronized BigInteger decrypt(BigInteger message) {

return message.modPow(d, n);

}

/** Generate a new public and private key set. */

public synchronized void generateKeys() {

SecureRandom r = new SecureRandom();

BigInteger p = new BigInteger(bitlen / 2, 100, r);

BigInteger q = new BigInteger(bitlen / 2, 100, r);

n = p.multiply(q);

BigInteger m = (p.subtract(BigInteger.ONE)).multiply(q

.subtract(BigInteger.ONE));

e = new BigInteger("3");

while (m.gcd(e).intValue() > 1) {

e = e.add(new BigInteger("2"));

}

44

d = e.modInverse(m);

}

/** Return the modulus. */

public synchronized BigInteger getN() {

return n;

}

/** Return the public key. */

public synchronized BigInteger getE() {

return e;

}

7.2 DES Algorithm:

public class DESHelper {

public static String encrypt(String seed, String cleartext)

throws Exception {

byte[] rawKey = getRawKey(seed.getBytes());

byte[] result = encrypt(rawKey, cleartext.getBytes());

return toHex(result);

}

public static String decrypt(String seed, String encrypted)

throws Exception {


byte[] enc = toByte(encrypted);

byte[] result = decrypt(rawKey, enc);

return new String(result);

}

45

private static byte[] getRawKey(byte[] seed) throws Exception {

KeyGenerator kgen = KeyGenerator.getInstance("DES");

SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");

sr.setSeed(seed);

kgen.init(64, sr); // 192 and 256 bits may not be available

SecretKey skey = kgen.generateKey();

byte[] raw = skey.getEncoded();

return raw;

}

private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {

SecretKeySpec skeySpec = new SecretKeySpec(raw, "DES");

Cipher cipher = Cipher.getInstance("DES");

cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

byte[] encrypted = cipher.doFinal(clear);

return encrypted;

}

private static byte[] decrypt(byte[] raw, byte[] encrypted)

throws Exception {



cipher.init(Cipher.DECRYPT_MODE, skeySpec);

byte[] decrypted = cipher.doFinal(encrypted);

return decrypted;

}

public static String toHex(String txt) {

return toHex(txt.getBytes());

}

46

public static String fromHex(String hex) {

return new String(toByte(hex));

}

public static byte[] toByte(String hexString) {

int len = hexString.length() / 2;

byte[] result = new byte[len];

for (int i = 0; i < len; i++)

result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),

16).byteValue();

return result;

}

public static String toHex(byte[] buf) {

if (buf == null)

return "";

StringBuffer result = new StringBuffer(2 * buf.length);

for (int i = 0; i < buf.length; i++) {

appendHex(result, buf[i]);

}

return result.toString();

}

private final static String HEX = "0123456789ABCDEF";

private static void appendHex(StringBuffer sb, byte b) {

sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));

}

47

7.3 AES Algorithm:

public class AESHelper {


throws Exception {




}


throws Exception {





}


KeyGenerator kgen = KeyGenerator.getInstance("AES");


sr.setSeed(seed);




return raw;

}


SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");

Cipher cipher = Cipher.getInstance("AES");

48



return encrypted;

}


throws Exception {





return decrypted;

}



}



}






16).byteValue();

return result;

}

49


if (buf == null)

return "";




}


}




}

7.4 Secure MD5 Hashing:

public class PasswordHash {

public String hashPassword(String password){

String passwordToHash = password;

String generatedPassword = null;

try {

// Create MessageDigest instance for MD5

MessageDigest md = MessageDigest.getInstance("MD5");

//Add password bytes to digest

md.update(passwordToHash.getBytes());

//Get the hash's bytes

byte[] bytes = md.digest();

50

//This bytes[] has bytes in decimal format;

//Convert it to hexadecimal format

StringBuilder sb = new StringBuilder();

for(int i=0; i< bytes.length ;i++)

{

sb.append(Integer.toString((bytes[i] & 0xff) + 0x100, 32).substring(1));

}

//Get complete hashed password in hex format

generatedPassword = sb.toString();

System.out.println(generatedPassword);

return generatedPassword;

}

catch (NoSuchAlgorithmException e)

{

e.printStackTrace();

return null;

}

}

}

51

Chapter 8.0 Testing and result

The aim of the project is to develop an application which can send encrypted message to the

receiver from the android device since android devices or any mobile the text messages are having

limitations in the size around 160 characters per message so because of that reason the security

protocol will not be working with big text messages but still we have implemented to show the

application is more in need for the todays software world due the heavy growth of hackers in the

network and this application can be enhanced to send big text messages in the future.

52

References

Cohen, F. (1990-1995). Specialising in Information protection since 1977. Fred chohen and assosiates.

Daley, W. (1999). Data encryption standard. Gaithersburg.: U.S department of Commerce.

DHT Technologies. (n.d.). www.dhtusa.com. Retrieved from

http://www.dhtusa.com/media/AndroidInternals.pdf:

http://www.dhtusa.com/media/AndroidInternals.pdf

Federal information processing standards publications. (November 26,2001). Advanced Encryption

standard. National institute of standards and Technology.

Kozushko, H. (11/28/2003). MD5 Algoritham.

matthews, J. o. (2007). A study of passwords and Methods used in Brute force SSH attacks. New York :

Department of computer science , Clarkson University.

Qijun Gu, P. L. (n.d.). Denial of service attacks. Texas.: Department of computer science , Texas state

university.

scarvalone, M. (2009). RSA Encryption and DIffie Hellman key exchange. RSA Encryption .

Shafi Goldwasser, M. B. (July 2008). Lecture notes on cryptography. Cryptography, 14.

spaight, J. (n.d.). Google android operating system.

stallings, W. (n.d.). Cryptography and Network security.

Tom. (2015). Toms guide. Retrieved from www.tomsguide.com: http://www.tomsguide.com/us/pictures-

story/654-best-messaging-apps.html

wichers, D. (2013). OWASP Top 10 . Creative Commons attribution share.

Bishop, M. (2003) “What is computer security?,” Security & Privacy, IEEE, 1(1), 67–69.

Bishop, M. (2004) Introduction to Computer Security, Addison-Wesley Professional.

53

Choo, K.-K.R., service), S. (Online (2009) Secure Key Establishment [online], Springer Science+Business

Media, LLC: Boston, MA, available:

http://ul.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwY2AwNtIz0EUrE1IM0yyNU0zNjV

ITzY2NLJOSgRwTw2RLYAVibmIA3m6BuOIYqYB3E2JgSs0TZZBwcw1x9tAtzYmHjmrEm1qC

Dp8zFGPgTQQtBc8rAW8ZS5FgUDC3TDRKMTKzsEiySDRJTTW2SDNKMgel7KS0NIPUZGM

AOxwoaw.

Coffey, T., Saidha, P. (1996) “Non-repudiation with mandatory proof of receipt,” ACM SIGCOMM

Computer Communication Review, 26(1), 6–17, available:

http://portal.acm.org/citation.cfm?doid=232335.232338.

Diffie, W., Hellman, M.E. (1979) “Privacy and authentication: An introduction to cryptography,”

Proceedings of the IEEE.

Eskicioglu, A.M., Litwin, L. (2001) “Cryptography,” Potentials, IEEE.

Ganesan, P., Venugopalan, R., Peddabachagari, P., Dean, A., Mueller, F., Sichitiu, M. (2003) “Analyzing

and modeling encryption overhead for sensor network nodes,” Proceedings of the 2nd ACM

international conference on Wireless sensor networks and applications - WSNA ’03, 151, available:

http://portal.acm.org/citation.cfm?doid=941350.941372.

Ganley, M. (2006) “Introduction – Cryptography,” Information Security Technical Report, 11(2), 67,

available: http://www.sciencedirect.com/science/article/pii/S1363412706000227 [accessed 23 Aug

2014].

GitHub, I. (2014a) Multiparty Protocol Specification [online], available:

https://github.com/cryptocat/cryptocat/wiki/Multiparty-Protocol-Specification.

GitHub, I. (2014b) Design and Functionality [online], available:

https://github.com/cryptocat/cryptocat/wiki/Design-and-Functionality.

54

Appendix

AESHelper.java

package com.proj.myapp;

import java.security.SecureRandom;

import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

import javax.crypto.SecretKey;

import javax.crypto.spec.SecretKeySpec;

public class AESHelper {


throws Exception {




}


throws Exception {





}


KeyGenerator kgen = KeyGenerator.getInstance("AES");


sr.setSeed(seed);



55


return raw;

}






return encrypted;

}


throws Exception {





return decrypted;

}



}



}






16).byteValue();

return result;

}

56


if (buf == null)

return "";




}


}




}

}

DESHelper.Java


import java.security.SecureRandom;


import javax.crypto.KeyGenerator;

import javax.crypto.SecretKey;

import javax.crypto.spec.SecretKeySpec;

public class DESHelper {


throws Exception {




57

}


throws Exception {





}


KeyGenerator kgen = KeyGenerator.getInstance("DES");


sr.setSeed(seed);




return raw;

}






return encrypted;

}


throws Exception {





return decrypted;

}


58


}



}






16).byteValue();

return result;

}


if (buf == null)

return "";




}


}




}

}

59

Encryptmessage.java


import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

import android.widget.Toast;

public class EncryptMessage extends Activity{

EditText edtEncryptedata;

TextView txtDecrypteShow;

Button btnDecrypte;

@Override

protected void onCreate(Bundle savedInstanceState) {

// TODO Auto-generated method stub

super.onCreate(savedInstanceState);

setContentView(R.layout.encryptmessage);

edtEncryptedata = (EditText) findViewById(R.id.edtencryptedata);

txtDecrypteShow = (TextView) findViewById(R.id.txtDecrypteShow);

btnDecrypte = (Button) findViewById(R.id.btn_decryptedata);

btnDecrypte.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View arg0) {

if (!edtEncryptedata.getText().toString().equals("")) {

String msg =edtEncryptedata.getText().toString();

60

try {

String strMessage = AESHelper.decrypt("BREAK", msg);

txtDecrypteShow.setText(strMessage);

} catch (Exception e) {

// TODO: handle exception


Toast.makeText(EncryptMessage.this, "Not an encrypte

text", Toast.LENGTH_LONG).show();

}

} else {

Toast.makeText(EncryptMessage.this, "Please enter encrypte

text", Toast.LENGTH_LONG).show();

}

}

});

}

}

61

Mainactivity.Java

ackage com.proj.myapp;

import android.net.Uri;


import android.provider.ContactsContract;


import android.content.Intent;

import android.database.Cursor;

import android.telephony.gsm.SmsManager;

import android.util.Log;

import android.view.Menu;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.ArrayAdapter;

import android.widget.Button;


import android.widget.Spinner;

import android.widget.Toast;

@SuppressWarnings("deprecation")

public class MainActivity extends Activity implements OnClickListener {

String algo[];

EditText etEnterNumber, etTextMsg;

Button btnSend, btnDecrypt, btnSelectcontact;

String plainText, cipherText, strPhoneNum;

private static final int PICK_CONTACT = 11;

Spinner spinner1;

62

@Override



setContentView(R.layout.activity_main);

etEnterNumber = (EditText) findViewById(R.id.etEnterNumber);

etTextMsg = (EditText) findViewById(R.id.etTextMsg);

btnSend = (Button) findViewById(R.id.btnSend);

btnDecrypt = (Button) findViewById(R.id.btnDecrypt);

btnSelectcontact = (Button) findViewById(R.id.btn_selectcontact);

spinner1 = (Spinner) findViewById(R.id.spinner1);

algo = getResources().getStringArray(R.array.alog);

ArrayAdapter<String> algoAdapter = new ArrayAdapter<String>(this,

android.R.layout.simple_spinner_item, algo);

spinner1.setAdapter(algoAdapter);

btnSend.setOnClickListener(this);

btnDecrypt.setOnClickListener(this);

btnSelectcontact.setOnClickListener(this);

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.main, menu);

return true;

}

@Override

public void onClick(View arg0) {


switch (arg0.getId()) {

case R.id.btnSend:

plainText = etTextMsg.getText().toString();

strPhoneNum = etEnterNumber.getText().toString();

if (!plainText.equalsIgnoreCase("") &&

!strPhoneNum.equalsIgnoreCase("")) {

try {

63

cipherText = AESHelper.encrypt("BREAK", plainText);

sendSMS(strPhoneNum, cipherText);

Log.d("", cipherText);



sendSMS(strPhoneNum, plainText);

}

} else {

Toast.makeText(getApplicationContext(),

"Please fill all the fields", Toast.LENGTH_LONG)

.show();

}

break;

case R.id.btnDecrypt:

Intent intent1 = new Intent(MainActivity.this, EncryptMessage.class);

startActivity(intent1);

break;

case R.id.btn_selectcontact:

Intent intent = new Intent(Intent.ACTION_PICK,

ContactsContract.Contacts.CONTENT_URI);

startActivityForResult(intent, PICK_CONTACT);

break;

}

}

private void sendSMS(String phoneNumber, String message) {

SmsManager sms = SmsManager.getDefault();

sms.sendTextMessage(phoneNumber, null, message, null, null);

Toast.makeText(getApplicationContext(),

"Message sent", Toast.LENGTH_LONG)

.show();

}

@Override

64

protected void onActivityResult(int requestCode, int resultCode, Intent

data) {


super.onActivityResult(requestCode, resultCode, data);

switch (requestCode) {

case PICK_CONTACT:

if (resultCode == Activity.RESULT_OK) {

Uri contactData = data.getData();

try {

Cursor cursor = getContentResolver().query(contactData,

null, null, null, null);

if (cursor.moveToFirst()) {

String id = cursor

.getString(cursor

.getColumnIndexOrThrow(ContactsContra

ct.Contacts._ID));

String hasPhone = cursor

.getString(cursor

.getColumnIndex(ContactsContract.Cont

acts.HAS_PHONE_NUMBER));

if (hasPhone.equalsIgnoreCase("1")) {

Cursor phones = getContentResolver()

.query(ContactsContract.CommonDataKinds.P

hone.CONTENT_URI,

null,

ContactsContract.CommonDataKinds.

Phone.CONTACT_ID

+ " = " + id, null, null);

phones.moveToFirst();

String cNumber = phones.getString(phones

.getColumnIndex("data1"));

etEnterNumber.setText(cNumber);

}

}

65



}

}

break;

}

}

}

RSAhelper.Java


import java.security.Key;

import java.security.KeyPair;

import java.security.KeyPairGenerator;


public class RSAHelper {

KeyPair kp;

Key publicKey = null;

Key privateKey = null;

byte[] decodedBytes = null;

byte[] encodedBytes = null;

66

RSAHelper() {

// Original text

// Generate key pair for 1024-bit RSA encryption and decryption

try {

KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");

kpg.initialize(256);

kp = kpg.genKeyPair();

publicKey = kp.getPublic();

privateKey = kp.getPrivate();


}

}

public void encrypt(String text) {

// Encode the original data with RSA private key

try {

Cipher c = Cipher.getInstance("RSA");

c.init(Cipher.ENCRYPT_MODE, privateKey);

encodedBytes = c.doFinal(text.getBytes());


}

// tvencoded.setText("[ENCODED]:\n" +

// Base64.encodeToString(encodedBytes, Base64.DEFAULT) + "\n");

}

// Decode the encoded data with RSA public key

public String decrypt() {

try {

Cipher c = Cipher.getInstance("RSA");

c.init(Cipher.DECRYPT_MODE, publicKey);

decodedBytes = c.doFinal(encodedBytes);

return new String(decodedBytes);


return null;

}

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}

// TextView tvdecoded = (TextView)findViewById(R.id.tvdecoded);

// tvdecoded.setText("[DECODED]:\n" + new String(decodedBytes) + "\n");

}

Showmsg.java


import java.security.Key;

import java.security.KeyPair;

import java.security.spec.X509EncodedKeySpec;




import android.speech.tts.TextToSpeech;


public class ShowMsg extends Activity{

String bodytext;

EditText etrecmsg;

TextToSpeech tts;

@Override




setContentView(R.layout.recmsg);

etrecmsg = (EditText) findViewById(R.id.etrecmsg);

Intent intent = getIntent();

bodytext = intent.getExtras().getString("message");

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try {

//String message = AESHelper.decrypt("BREAK", bodytext);

//etrecmsg.setText(message);

if(bodytext.contains("-")){

String[] parts = bodytext.split("-");

}



etrecmsg.setText("Not an encrypted Message:\n" + bodytext);

}

}

}

SMSreceiver


import java.util.ArrayList;

import java.util.List;

import android.content.BroadcastReceiver;

import android.content.Context;



import android.telephony.SmsMessage;

public class SmsReciever extends BroadcastReceiver {

String address;

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String body;

// @TargetApi(Build.VERSION_CODES.DONUT)

@Override

public void onReceive(Context context, Intent intent) {

List<SmsMessage> smsMessages = getSmsMessages(intent);

for (SmsMessage smsMessage : smsMessages) {

address = smsMessage.getOriginatingAddress();

body = smsMessage.getMessageBody();

Intent intent2 = new Intent(context, ShowMsg.class);

intent2.putExtra("phone", address);

intent2.putExtra("message", body);

intent2.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

context.startActivity(intent2);

}

}

private List<SmsMessage> getSmsMessages(Intent intent) {

List<SmsMessage> smsMessages = new ArrayList<SmsMessage>();

// ---get the SMS message passed in---

Bundle bundle = intent.getExtras();

if (bundle != null) {

// ---retrieve the SMS message received---

Object[] pdus = (Object[]) bundle.get("pdus");

for (int i = 0; i < pdus.length; i++) {

SmsMessage msg = SmsMessage.createFromPdu((byte[]) pdus[i]);

smsMessages.add(msg);

}

}

return smsMessages;

}

}

70

Splashscreenactivity.Java





import android.os.Handler;

import android.view.Window;

public class SplashScreenActivity extends Activity {

private static int SPLASH_TIME_OUT = 3000;

@Override



requestWindowFeature(Window.FEATURE_NO_TITLE);

setContentView(R.layout.splashscreen);

if (!isTaskRoot()) {

Intent intent = getIntent();

String action = intent.getAction();

if (intent.hasCategory(Intent.CATEGORY_LAUNCHER) && action != null

&& action.equals(Intent.ACTION_MAIN)) {

finish();

return;

}

} else {

new Handler().postDelayed(new Runnable() {

@Override

public void run() {

// Create an intent that will start the main activity.

Intent intentLogin = new Intent(SplashScreenActivity.this,

MainActivity.class);

SplashScreenActivity.this.startActivity(intentLogin);

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// Finish splash activity so user can't go back to it.

SplashScreenActivity.this.finish();

}

}, SPLASH_TIME_OUT);

}

}

@Override

public void onBackPressed() {

}

}

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