An Introduction To Encryption And Decryption

An Introduction To Encryption And Decryption CHAPTER 1 This thesis proposes a VHSIC Hardware Description Language (VHDL) design of Encryption and Decryption Algorithm for Data. In this chapter, the challenges of cryptography is firstly presented. This chapter also briefly discusses the problem definition, scope of work and the thesis objectives are also highlighted.Finally, the chapter end with the chapter organization. The dissertation presentation is provided at the end 1.1 An introduction to Encryption and Decryption, a type of cryptography Encryption and Decryption, a type of cryptography, refers to the process of scrambling information so that the observer cannot be detecting the data. Cryptographic key is a piece of data used to encrypt or decrypt to plaintext. (Alex Brennen V., 2004) The Crypto, from the word cryptographic mean is it has its origins in the Greek word KRUOTOS, which means hidden. Thus the objective of cryptography is to hide information so that only the intended recipient can read it.[2] . Cryptographic is a protocol or method of performing encryption and decryption (Alex Brennen V., 2004). There are two types of cryptographic: symmetric and asymmetric key. Figure 1.1 is example a symmetric cryptographic has a single key, which is used for both encrypting and decrypting information. Data Encryption and Decryption is a well-known example of symmetric cryptographic. In symmetric cryptographic, public-key cryptographic uses complementary pair of keys to divided the process of encryption and decryption. This process is shown in Figure 1.2. This part is discuss about the symmetric-key cryptographic only.[3]. The proposed projects is to create the algor ithms where it is use to convert of information, rearranging the original massage produce output referred as ciphertext Plaintext Plaintext Ciphertext Key Figure 1.1: Symmetric Cryptographic Plaintext Plaintext Ciphertext Encryption Key and Decryption Key Figure 1.2: Public-Key Cryptographic 1.2 Problem Statement At present there are many encryption and decryption, especially in the communication system provided in a variety of application. Encryption and decryption is particularly impacted in the field of military communications and reliable security data to protection for transmitting. This ciphertext is used in the military is to send information such as direction, strategy, secret codes and other information that can not be know by the national foe during the war.[4] Creating this system is the process by which information can not be detect by the national foe. The information can not be recognizing by the national foe because this system is using the process to encrypt data and decrypt data. [4] 1.3 Scopes of Work Based on available software resources, limited time frame and expertise, this research project is narrowed down to the following scope of work: 1. The project is only to design fixed 64-bit input of data block size, 64-bit output of data block size and 56-bit of key size based on an Encryption and Decryption algorithm . 2. The projects is limited to design, to synthesis, to simulate and to verify the design in Altera Quartus II software. Objective The project are to create a system that can protect electronic data (secret information) which Consist of encryption and decryption process and to fully design an encryption and decryption algorithm using VHDL. The objectives of this project are To understand how the Encryption and Decryption process. To fully design an Encryption algorithm and Decryption algorithm using VHDL. Encryption and decryption which support 64-bit input of data block size, 64-bit output of data block size and 56-bit of key size. To make use Quartus II software as a design and synthesis tool. 1.4 Chapter Organization Chapter 1: This chapter starts with an Introduction which highlights the problems under investigation by describing the status of problem conceptually and theoretically. It contains the introduction of the thesis, problem statement and scope of study, objective of the project, and the chapter organization. Chapter 2: This chapter is a Literature Review that compiles the studies done by others based on the title of the project. Under the literature review, this chapter discussed on the features need to be include in designing the system. Chapter 3:. The methodology chapter describes the steps that has been taken while doing the project from the beginning until the end. The main content of the chapter are the flow charts and the description of each step of the process. Chapter 4: This chapter presents the result of the algorithm and discussion observed. The results obtained are presented as a series of figures, tables, with textual description and discussion. The analysis outcome of the research is also discussed in relation to the evidences obtained from project work and theories reported in Literature Review . Chapter 5: The chapter is the Conclusion of the thesis and which signalized the whole project a done CHAPTER 2 LITERATURE REVIEW 2.0. Overview This chapter is to introduce the host range of background information and research for this thesis. Most methods have been widely used to determine how the process of encryption and decryption. Theoretical method is presented using the VHDL. Chooses the VHDL programming for design encryption and decryption because this programming is very direct forward is compare other programming. For example Cadence and C++ programming. Both programming is very complicated. In this chapter, the Literature review of the research is discussed. The main topics discussed in this chapter are shown below: Symmetric cryptography Encryption Decryption Operations of Encryption and Decryption Data Encryption and Decryption VHDL (VHSIC Hardware Description Language) 2.1. Symmetric key cryptography The symmetric key scheme is the conventional method of cryptography. The scheme uses the similar key to encode and decode in information. In a symmetric key algorithm, in the normal case, the communication only uses only one key. For example if Z user Z sends the secret symmetric key to an X user before the start of the communication between them. Part Z and X use the same symmetric key to encryption and decryption the message. Encryption and Decryption are example of symmetric key algorithm. Figure 2.2 shows the symmetric key cryptography. The symmetric key algorithm is faster than an asymmetric key algorithm. There are two classes of symmetric key cryptography as block ciphers and stream ciphers. [6] Plaintext X Plaintext Z Encryption and Decryption Symmetric Key Figure 2.1: The symmetric key cryptography 2.2 Block Cipher Block cipher is a type of symmetric-key decryption and encryption algorithm. The symmetric-key decryption and encryption that is a fixed length block of plaintext data into block ciphertext data. The block size is 64 bit. The block size can be upgrade to 128 bit, 256 bit or 512 bit if the process becomes advanced. Block ciphers operate on large blocks of data. The encryption and decryption of plaintext with a block cipher will result in the same when the same key is used. From the figure 2.3, it can be seen that show the Block Cipher Plaintext Plaintext Block Cipher Encryption and Block Cipher Decryption Symmetric Key Figure 2.2: Block Cipher 2.3 Stream Cipher Stream cipher is a type of symmetric encryption and decryption algorithm. Stream ciphers much faster than any block cipher. Stream ciphers operate on smaller units of plaintext. The encryption and decryption of plaintext with a stream cipher will result in the same when the same key is used. From the figure 2.3, it can be seen that show the Stream Cipher Plaintext Plaintext Stream Cipher Encryption and Stream Cipher Decryption Symmetric Key Figure 2.2: Stream Cipher Advantages of Symmetric Key Cryptography The main advantages of symmetric key (public key) cryptography are improved security and expediency. Other major advantages from the symmetric key (public key) are that they can provide a technique for digital signatures. Verification via secret-key system requires a shared secret and sometimes requires trust of a third party. For example, Kerberos verification system involves a button-secret data center that stores copies of all user secret key. An attack on the database will enable the falsification of the system. Public key verification, on the other hand, prevents of rejection, and each user has a responsibility to protect his private key. [7] 2.3 Disadvantages of Symmetric -Key Cryptography The disadvantage of symmetric cryptography is that it presumes two parties have agreed on a key and been able to exchange that key in a secure manner prior to communication. This is a significant challenge. Symmetric algorithms are usually mixed with public key algorithms to obtain a blend of security and speed. Disadvantage of using symmetric-key cryptography for encryption and decryption is faster. There are popular secret-key encryption and decryption technique that are considerably faster than any at present available symmetric-key encryption and decryption technique. However, public-key cryptography can be used by means of secret-key cryptography to obtain the optimum of both worlds. For encryption, the optimum solution is to join together with public-key and secret-key systems in order to obtain both the security advantages of public-key systems and the velocity advantages of secret-key systems. The public-key system can be make use of to encrypt a secret key which is make use of to encrypt the bulk of a information or message. Public-key cryptography may be vulnerable to impersonation, although, also furthermore if usersà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ãƒ ¢Ã¢â‚¬Å¾Ã‚ ¢ private keys are not available. A successful assail attack pounce on a certification authority will permit a national foe to impersonate whomever the adversary pick out to by using a public-key certificate from the compromised authority to bind a key of the national foe choice to the name of another user In some plight, public-key cryptography is not obligatory and secret-key cryptography alone is enough. This belonging to environments where secure secret-key assent can take place, for example by users confluence in private. It also belonging environments where a sole authority knows and manages all the keys. Formerly the authority knows everyoneà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ãƒ ¢Ã¢â‚¬Å¾Ã‚ ¢s keys already there is not much excess for some to be public and others private. And yet, public-key cryptography is normally not obligatory in a single-user environment. Example, if want to keep personal message or information encrypted, can do so with any secret-key encryption algorithm using personal password as the secret key. Furthermore, public-key cryptography is optimum equivalent for an open multi-user environment. Public-key cryptography is not intention to substitute secret-key cryptography, but nevertheless to complementary it, to make it more safety [8] 2.4 Encryption Encryption is a form of cryptography that to change the plaintext into ciphertext. A cipher is a algorithms for the encryption. Encryption is the principle of such security step as digital signatures, digital certificates, and the public key infrastructure. Computer-based encryption method use keys to encrypt and decrypt information. A key is in binary number. The key is one part of the encryption process. It must be used in connection with an encryption algorithm to generate the cipher text. Encryption is the symmetric or asymmetric. Ciphers were repeatedly used directly for Encryption without supplement procedures such as ratification. The extremely used kind of encryption is symmetric Encryption, which is aptly named for the reason that it uses one key for both the encryption and decryption system [9] 2.5 Decryption Decryption is the opposite or moving from the ciphertext back to the plaintext. A cipher is a algorithms for the decryption. The specification operation of a cipher is to manage with both by the algorithm and in each example by a key. Decryption is the symmetric or asymmetric. Ciphers were repeatedly used directly for decryption without supplement procedures such as ratification. The extremely used kind of decryption is symmetric decryption, which is aptly named for the reason that it uses one key for both the encryption and decryption system [10]. 2.6 Operations of Encryption and Decryption An encryption and decryption scheme consists of three Standard algorithms: A Key Generation Algorithm. For a symmetric key, this is often an algorithm that simply picks a random key of a certain length. The symmetric key scheme is the conventional method of cryptography. The scheme uses the similar key to encode and decode in information. An Encryption Algorithm. This takes as input a message (or plaintext) and some kind of key, and outputs a ciphertext. Encryption is to change the plaintext into ciphertext A decryption algorithm. This takes as input a ciphertext and some kind of key, and outputs a message.Decryption is to change the ciphertext back to the plaintext 2.7 Data Encryption and Decryption This system works by encrypting and decrypting groups of only 64 message bits, which is the same as 16 hexadecimal number. To do the encryption and decryption, this system uses symmetric keys where are also apparently 16 hexadecimal number long, or 64 bits long. However, every 8th key bit is ignored in this algorithm, so that the effective key size is 56 bits. But, in any case, 64 bits (16 hexadecimal digits) is the round number upon which Encryption and Decryption is organized. The process is explain in Figure 1.2, it can be seen that the process of encrypt and decrypt, if take the plaintext message is 2872762F771B15E8, and encrypt it with the key 0000000000000001, the ciphertext produced 1234567890987654. If the ciphertext is decrypted with the same secret key 0000000000000001, the result is the original plaintext 2872762F771B15E8. Input data 2872762F771B15E8 Key Encryption Ciphertext 123345678890987654 Key Decryption Key Original input 2872762F771B15E8 Figure 1.2: Simple Block Diagram Process Encryption and Decryption using Feistel Algorithm 2.4 VHDL History (VHSIC Hardware Description Language) In order to complete the design, the VHDL is one of the most important tools used. Device description language VHDL is a great acronym stands for the Very High Speed Integrated Circuit Hardware Description language. It was originally developed on the orders of the U.S Department of Defense. They need a more efficient way to document the behavior of the ASIC design service companies were present.[11,12] It was developed as an alternative to the huge, highly complex manuals that were the norm. The idea to simulate such a description was immediately an attractive prospect and logic simulators were developed could take a VHDL description as input. From here synthesis to the hardware level became a focus of study and still is. Current state-of the- art synthesis tools can create hardware for a large subset of the VHDL language and should at least support the synthesizable subset in IEEE1076.6-1999. The syntax of VHDL was derived from Ada, with constructs added to handle the parallelism th at appears in hardware designs. The language is strongly typed and case insensitive. [13,14] The initial version of the language that was presented in the IEEE standard 1076-1987 was somewhat limited and a new version appeared in 1993 in IEEE standard 1079-1993, which improved the consistency of the language. There have been various reviews and updates to the standard of the languages since, but the 1993 version is the most prominent and widely used. Both versions of the language ignored the need for a multi-valued logic type which is where the IEEE standard 1164 comes in.[15] This standard defines a 9-valued logic type called standard logic. This has become the standard type to use for multi-valued logic in VHDL descriptions. The language has been further extended in a series of libraries. One such library is the numeric std library which implements a signed and unsigned type. These types allow for arithmetic to be performed on arbitrarily sized logic vectors. [16] 2.4 VHDL (VHSIC Hardware Description Language) In order to complete the design, the VHDL is one of the most important tools used. Device description language VHDL is a great acronym stands for the Very High Speed Integrated Circuit Hardware Description language. It was originally developed on the orders of the Department of Defense. They need a more efficient way to document the behavior of the ASIC design service companies were present.[ represented 11,12] VHDL (VHSIC Hardware Description Language) was originally adopted by the U.S Department of Defense. The initial version of VHDL, designed to IEEE standard 1076-1987, included a wide range of data types, including numerical (integer and real), logical (bit and boolean), character and time, plus arrays of bit called bit_vector and of character called string. [16] [1] Laura E.Hunter,Brian Barber,Melissa Craft,Norris L.Johnson Jr,Jeffery A Martin,Tony Piltzecker. MCSE. Implementing PKI in a Window Server 2003 Network.Chapter 4.Page 185 [2] Mohan Krishnamurthy, Eric S.Seagren, Raven Alder, Aaron W.Bayles, Josh Burke, Skip Carter Eli Faskha How to Cheat at Securing Linux.page:250 [3] Dr.Everett F.Carter jr,Jeremy Faircloth,Curtis Franklin jr,Larry Loeb, Hack Proofing XML Page:193 [4] The Point Of Encryption By Dr.Colin Walter,Available at http://www.securitydocs.com/pdf/3301/PDF [5] Aram Khalili, Department of Computer Science, University of Maryland. Available at http://www.cs.umd.edu/~waa/414-F01/symmetric.pdf [6] D. Richard Kuhn ,Vincent C. Hu ,W. Timothy Polk, Shu-Jen Chang ,National Institute of Standards and Technology Introduction to Public Key Technology and the Federal PKI Infrastructure [6.5] Contributed by LE Webmaster Kerberos Authentication System Available at http://www.linuxexposed.com/index2.php? option=com_contentdo_pdf [7]. Advantaged of Public-Key Cryptography ,Available at http://users.hack.gr/dij/crypto/overview/publickey.html [8] Disadvantages of Public-Key Cryptography ,Available at http://x5.net/faqs/crypto/q4.html [9] Manuel Mogollon University Of Dallas USA.Cryptography and Security services. Page: 51 [10] Mohan Krishnamurthy, Eric S.Seagren,Raven Alder, Aaron W.Bayles,Josh Burke,Skip Carter Eli Faskha How To Cheat at Securing Linux .page:251 [11]. Copyright  © 1999 by John F. Wakerly Combinational Logic Design Principles,The VHDL Hardware Design Language. Page :1-35. [12] Deepak Jain . Object Oriented Programming Constructs in VHSIC Hardware Description Language, Delhi Institute of Advanced Studies [13] Institute of Electrical and Electronics Engineers, IEEE 1076-1987: IEEE Standard VHDL Language Reference Manual, 1987 [14] Institute of Electrical and Electronics Engineers, IEEE Std 1076.6-1999: IEEE Standard for VHDL Register Transfer Level (RTL) synthesis, 1999. [15] Institute of Electrical and Electronics Engineers, IEEE 1076-1993: IEEE Standard VHDL Language Reference Manual, 1993. [16] E.P.M. van Diggele. Translation of SystemC to Synthesizable VHDL, MSc Thesis, Delft University of Technology.

I Stand Here Ironing Essay

When reading the short story ? I Stand Here Ironing? written by Tillie Olsen I analyzed the story by using both feminist criticism and the formalist strategy. The author uses a iron as a metaphor for how the woman in the story tells the life of her daughter and why her daughter is the way that she is. In a way the woman lays everything out on the table and irons it out straight. Many single mothers can relate to this story because it tells about the hardships that some unfortunate mothers? have to face. In this story Emily was born during the depression. Her mother had to work because she was a young single parent, as read in the story Emily?s father could ? no longer endure?. I believe that the mother cared for Emily she hated to leave her with her fathers relatives. Olsen wrote that the character did everything by the book she breast fed by the clock like they said. At that time ?they? were the male doctors who thought they knew all about motherhood. As a woman I would think Redmond2 that a woman would know what is best for both the mother and her child. By the end of the story the mother and daughter relationship grew a little closer Emily who lacked meaning found a talent . Emily also gained a sense a sense of responsibility by taking care of her siblings. Olsen uses the iron as a metaphor a number of times through out the story. In the first paragraph the mother says, ?and what you asked me moves back and forth with the iron?. I think that the mother is trying to sort out the good and the bad through out Emily?s life. She tells of what had to be done not what should have been done. The woman realizes that her daughter lacks meaning in life. The mother questions herself on the upbringing of her oldest daughter Emily compared to the other children. In the last sentence of the story it reads ?help make it so that there is cause for her to know that she she is more than this dress on the ironing board, helpless before the iron? What the mother is trying to say is Emily is like she is because that?s how she brought her up it could be un helped at the time the mother is also reassuring herself by thinking she could be worse don?t we all have our faults?

Driving Safety and Distractions

Research question: driving safety and types of distractions Hypothesis: Driving safe and trying to avoid distractions can prevent thousands of accidents each year. People tend to let things like music, phones, makeup, and other things distract their driving. Acting more safely can prevent alot. The null hypothesis would be that it really doesn't matter about the distractions it is up to the person to drive safe. The number of participants that i will use for this research is thirty. The inclusion characteristics will be age, gender, and three different types of distractions. I on't think there will be no exclusion characteristics considering the study is using age and gender as well as different distraction characteristics. Yes the sample nedds to be diverse because we are studying driving between male and females. We are also studying the adult and teenager age groups against the different distractions that we intend to use. The type of sampling method that I will be using is strati sfied random sampling. This sampling is appropiate because i will be randomly selecting participants from each group so that their presentation in the sample is proportional to the epresentation in te population. I will generalize my sample to the male and female population. I will also use the teenage and adult groups. I will also generalize between the different types of distractions and there affect. The independent variables in my study will be men versues women. The dependent variable would the types of distractions that causes a person not to drive safely. I will be using the one-way annova test. This test is appropiate to use with the number of distractions being tested which will be three or more caterogories to compare against. The reliablity of this study is based off of the participants and how they react to the types of distractions. The validity would be how valid the distractions are to get a reaction out of the participants. For this study I will be using observational research in determing driving and types of distractions. I would set up a car simulation. Each participant would be driving and I would add a distraction to the experiment to observe the reaction of the person. I will also use data from different driving accidents to see what caused it and the age and gender of the person. Descriptive research si the deisgn being used. This research is good because I am using observational research and some archival data. The basic procedure that I will go through is to randomly pick male and females some that are teens and some adults. I will set upa car simulation and have each one drive and then present different distractions to see how they react. I can also see what was the one distractions that had the greatest effect and the one that had the least effect. Some ethical issues could be the race of the subjects, the area in which they live, health and mental issues. References: Occupational driver safety: Conceptualising a leadership-based intervention to improve safe driving performance[->0] Newnam, Sharon; Lewis, Ioni; Watson, Barry. Accident Analysis & Prevention (0001-4575) March 2012. Iss. Volume 45;p. 29-38 Source: Science Direct[->1] Teens Receive Grant to Develop Safe Driving Campaigns. [->2] Professional Safety (0099-0027) Oct2011. Vol. 56,Iss. 10;p. 29-29 Source: Academic Search Elite[->3] Protext Mobility Releases DriveAlert Safe Driving Solution for Android to Combat Distracted Driving[->4] Anonymous. Wireless News 2011-08-04. Source: Telecommunications (ProQuest)[->5] .Automotive; Safe Driving Starts with Safe Thinking[->6] Anonymous. Transportation Business Journal (1945-8436) 2011-07-03. Source: Military Collection[->7] Road safe seniors: Screening for age-related driving disorders in inpatient and outpatient settings[->8] Hill, Linda; Rybar, Jill; Baird, Sara; Concha-Garcia, Susanna; Coimbra, Raul; Patrick, Kevin. Journal of Safety Research (0022-4375) 2011-06-01. Vol. 42,Iss. 3;p. 165 Source: Research Library Complete (ProQuest)[->9] Older and Younger Drivers' Beliefs about Motor Vehicle Features to Benefit Their Safe Driving[-;10] Soyun Kim ; Michael S. Wogalter ; Christopher B. Mayhorn. Proceedings of the Human Factors and Ergonomics Society Annual Meeting September 2010. Vol. 54,Iss. 2;p. 160 – 164 Source: SAGE Journals Online[-;11] .Safe Driving Systems, LLC; Texting While Driving: Danger Eliminated with New Technology[-;12] Anonymous. Computer Business Week (1944-1541) 2010-04-08. Source: Science Journals[-;13] Age and gender differences in risky driving: The roles of positive affect and risk perception. Rhodes, Nancy; Pivik, Kelly Accident Analysis & Prevention (0001-4575) May 2011. Vol. 43, Iss. 3; p. 923-931 Source: Science Direct Age, skill, and Hazard perception in driving Borowsky, Avinoam; Shinar, David; Oron-Gilad, Tal Accident Analysis & Prevention (0001-4575) July 2010. Vol. 42, Iss. 4; p. 1240-1249 Source: Science Direct Mixed Signals on cellphone bans; Safety group seeks more data as states limit driving distractions Larry Copeland, USA Today 07 Jul 2011 Source: eLibrary Road Safety Program geared to students/ Driving distractions stressed at schools Magee, Maureen The San Diego Union- Tribune(1063-102x) 2009-10-22 Source: Newsstand Safety Campaign highlights Danger of Driving Distractions US FED NEWS Service, Including US State News 2009-06-03 Source: Research Library Complete Soglesby_M3:Assignment 2 [-;0] – http://www. sciencedirect. com. libproxy. edmc. edu/science? _ob=GatewayURL=citationSearch=4=SERIALSCENT=1=S0001-4575%2811%2900306-X=f657769fe706b77650817f650bfd1ffe [-;1] – http://www. sciencedirect. com. libproxy. edmc. edu/college [-;2] – http://search. ebscohost. com. ibproxy. edmc. edu/login. aspx? direct=true=afh=ehost-live=67047843 [-;3] – http://search. ebscohost. com. libproxy. edmc. edu/login. aspx? authtype=ip,uid=ehost=afh [-;4] – http://search. proquest. com. libproxy. edmc. edu/docview/880973357/citation/embedded/67K6C70KVQ8HHTJI? source=fedsrch [-;5] – http://search. proquest. com. libproxy. edmc. edu/telecomms [-;6] – http://search. proquest. com. libproxy. edmc. edu/docview /873326956/abstract/embedded/05S33OPH125WJ575? source=fedsrch [-;7] – http://search. proquest. com. libproxy. dmc. edu/military/ [-;8] – http://search. proquest. com. libproxy. edmc. edu/docview/886697220/abstract/embedded/YEPZ7R2PIKHVRMP5? source=fedsrch [-;9] – http://search. proquest. com. libproxy. edmc. edu/pqrl [-;10] – http://pro. sagepub. com. libproxy. edmc. edu/cgi/content/abstract/54/2/160 [-;11] – http://online. sagepub. com. libproxy. edmc. edu/ [-;12] – http://search. proquest. com. libproxy. edmc. edu/docview/198002167/abstract/embedded/67K6C70KVQ8HHTJI? source=fedsrch [-;13] – http://search. proquest. com. libproxy. edmc. edu/sciencejournals

History of the Caste System in India

The origins of the caste system in India and Nepal are not fully known, but castes seem to have originated more than 2,000 years ago. Under this system, which is associated with Hinduism, people were categorized by their occupations. Although originally caste depended upon a persons work, it soon became hereditary. Each person was born into an unalterable social status. The four primary castes are Brahmin, the priests; Kshatriya, warriors and nobility; Vaisya, farmers, traders and artisans; and Shudra, tenant farmers, and servants. Some people were born outside of (and below) the caste system. They were called untouchables or Dalits—the crushed ones. Theology Behind the Castes Reincarnation is the process by which a soul is reborn into a new material form after each life; it is one of the central features of the Hindu cosmology. Souls can move not only among different levels of human society but also into other animals. This belief is thought to be one of the primary reasons for the vegetarianism of many Hindus. Within a single lifetime, people in India historically had little social mobility. They had to strive for virtue during their present lives in order to attain a higher station their next time around. In this system, a particular souls new form depends upon the virtuousness of its previous behavior. Thus, a truly virtuous person from the Shudra caste could be rewarded with rebirth as a Brahmin in his or her next life. Daily Significance of Caste Practices associated with caste varied through time and across India, but all shared some common features. The three key areas of life historically dominated by caste were marriage, meals, and religious worship. Marriage across caste lines was strictly forbidden. Most people even married within their own sub-caste or jati. At mealtimes, anyone could accept food from the hands of a Brahmin, but a Brahmin would be polluted if he or she took certain types of food from a lower caste person. At the other extreme, if an untouchable dared to draw water from a public well, he or she polluted the water, and nobody else could use it. In religious worship, Brahmins, as the priestly class, presided over rituals and services including preparation for festivals and holidays, as well as marriages and funerals. The Kshatriya and Vaisya castes had full rights to worship, but in some places, Shudras (the servant caste) were not allowed to offer sacrifices to the gods. Untouchables were barred entirely from temples, and sometimes they were not even allowed to set foot on temple grounds. If the shadow of an untouchable touched a Brahmin, the Brahmin would be polluted, so untouchables had to lay face-down at a distance when a Brahmin passed. Thousands of Castes Although the early Vedic sources name four primary castes, in fact, there were thousands of castes, sub-castes, and communities within Indian society. These jati were the basis of both social status and occupation. Castes or sub-castes besides the four mentioned in the Bhagavad Gita include such groups as the Bhumihar or landowners, Kayastha or scribes, and the Rajput, a northern sector of the Kshatriya, or warrior, caste. Some castes arose from very specific occupations, such as the Garudi—snake charmers—or the Sonjhari, who collected gold from river beds. The Untouchables People who violated social norms could be punished by being made untouchables. This was not the lowest caste. The person deemed untouchable—and their descendants—were condemned and completely outside of the caste system. Untouchables were considered so impure that any contact with them by a caste member would contaminate the member. The polluted person would have to bathe and wash his or her clothing immediately.  The untouchables historically did work that no one else would do, like scavenging animal carcasses, leather-work, or killing rats and other pests.  Untouchables could not eat in the same room as caste members and could not be cremated when they died. Caste among Non-Hindus Curiously, non-Hindu populations in India sometimes organized themselves into castes as well. After the introduction of Islam in the subcontinent, for example, Muslims were divided into classes such as the Sayed, Sheikh, Mughal, Pathan, and Qureshi. These castes are drawn from several sources: The Mughal and Pathan are ethnic groups, roughly speaking, while the Qureshi name comes from the Prophet Muhammads clan in Mecca. Small numbers of Indians were Christian from around 50 CE onward. Christianity expanded in India after the Portuguese arrived in the 16th century. Many Christian Indians continued to observe caste distinctions, however. Origins of the Caste System Early written evidence about the caste system appears in the Vedas, Sanskrit-language texts that date from as early as 1500 BCE. The Vedas form the basis of Hindu scripture. The Rigveda, however, which dates from around 1700–1100 BCE, rarely mentions caste distinctions and is taken as evidence that social mobility was common in its time. The Bhagavad Gita, which dates from around 200 BCE–200 CE, emphasizes the importance of caste. In addition, the Laws of Manu or Manusmriti, from the same era, defines the rights and duties of the four different castes or varnas. Thus, it seems that the Hindu caste system began to solidify sometime between 1000 and 200 BCE. The Caste System During Classical Indian History The caste system was not absolute during much of Indian history. For example, the renowned Gupta Dynasty, which ruled from 320 to 550, was from the Vaishya caste rather than the Kshatriya. Many later rulers also were from different castes, such as the Madurai Nayaks (who ruled from 1559 to 1739) who were Balijas (traders). From the 12th century to the 18th century, much of India was ruled by Muslims. These rulers reduced the power of the Hindu priestly caste, the Brahmins. The traditional Hindu rulers and warriors, or Kshatriyas, nearly ceased to exist in north and central India. The Vaishya and Shudra castes also virtually melded together. Although the Muslim rulers faith had a strong impact on the Hindu upper castes in the centers of power, anti-Muslim feeling in rural areas actually strengthened the caste system. Hindu villagers reconfirmed their identity through caste affiliation. Nonetheless, during the six centuries of Islamic domination (roughly 1150–1750), the caste system evolved considerably. For example, Brahmins began to rely on farming for their income, since the Muslim kings did not give rich gifts to Hindu temples. This farming practice was considered justified so long as Shudras did the actual physical labor. The British Raj and Caste When the British Raj began to take power in India in 1757, they exploited the caste system as a means of social control. The British allied themselves with the Brahmin caste, restoring some of its privileges, which had been repealed by the Muslim rulers. However, many Indian customs concerning the lower castes seemed discriminatory to the British, so these were outlawed. During the 1930s and 1940s, the British government made laws to protect the Scheduled castes, untouchables and low-caste people. A movement toward the abolition of untouchability took place within Indian society in the 19th and early 20th centuries as well. In 1928, the first temple welcomed untouchables (Dalits) to worship with its upper-caste members. Mohandas Gandhi advocated emancipation for the Dalits, too, coining the term harijan or Children of God to describe them. Caste Relations in Independent India The Republic of India became independent on August 15, 1947. Indias new government instituted laws to protect the Scheduled castes and tribes which included both the untouchables and groups living traditional lifestyles. These laws include quota systems that help to ensure access to education and to government posts. Because of these shifts, a persons caste has become somewhat more of a political category than a social or religious one in modern India. Sources: Ali, Syed. Collective and Elective Ethnicity: Caste among Urban Muslims in India, Sociological Forum, vol. 17, no. 4, December 2002, pp. 593-620.Chandra, Ramesh. Identity and Genesis of Caste System in India. Gyan Books, 2005.Ghurye, G.S. Caste and Race in India. Popular Prakashan, 1996.Perez, Rosa Maria. Kings and Untouchables: A Study of the Caste System in Western India. Orient Blackswan, 2004.Reddy, Deepa S. The Ethnicity of Caste, Anthropological Quarterly, vol. 78, no. 3, Summer 2005, pp. 543-584.