The Police and Crime

The Police and Crime History of Criminal Investigation: The investigation of crime involves the study of various facts and findings, with the intention of finding whether an individual is guilty or not, for an offence. This process involves the use of a variety of techniques, which includes interviews, interrogations, forensic analysis, etc (Fisher Fisher, 2012). The investigation of crime is a concept that has a long history, and the function of detectives was able to develop gradually. However, it is important to explain that, it is the CID who had the responsibility of investigating crime. This was a specialized unit, responsible for investigating crime, and could be found in all police stations in the United Kingdom (Beauregard and Martineau, 2014). However, the powers of investigators were ambiguous. This is because there wasn’t any law that was able to spell out the role of investigators, and the rights of the people under investigation (Rossmo and Summers, 2015). This was a major challenge to the investigatory process, basically because the detectives could breach on the rights of people, because of the absence of a clear guideline on how to investigate (Taylor, Fritsch and Liederbach, 2014). Furthermore, investigators had very limited training. This had an impact of negatively affecting the efficiency of their investigations, hence the results. It is because of these limited training, that the status of investigatory officers was able to rise up very slowly. Organizational Processes: Crown Prosecution Service: Until 1984, it was the police department that was in charge of the investigation of criminal activities. The introduction of the 1984, law of Police and Criminal Evidence Act (PACE) is significant, because it was able to identify the role of the police officers, and the rights that the public had. This is with the intention of protecting the citizens from abuses by the police. Until 1986, it is the police who were responsible for investigating crime, and prosecuting crime. However, this responsibility and duties changed in the year 1986. This is basically because of the emergence of the Crown Prosecution Office. This came into being with the enactment of the 1985 Prosecution Offences Act. The Crown Prosecution Office has the responsibility of prosecuting every criminal charge, brought against an individual (Newburn, 2012). This office is very important because it ensures that the police would not be the prosecutors, as well as the investigators of a criminal offence. This helps in protecting the citizens from abuses by police officers, who may carry out inadequate investigation, and press charges with limited evidence (Carr-Hill Stern, 2014). The impact of this situation is that the police officers may prosecute an innocent person, or they may fail to get justice to the victim, because of the inability of successful prosecuting the case, leading to a conviction. The Crown Prosecution Service is therefore important, basically because it would ensure that the quality of investigation is high, and cases are brought to the courts, if there is sufficient evidence warranting their prosecution (Baker, 2013). This has therefore helped in solving issues pertaining to poor investigation of an offence. Volume Crimes: In as much as there is the existence of the crown prosecution service, it is very difficult to solve and investigate volume crimes (Beauregard and Martineau, 2014). These are the majority of offences that are committed in England and Wales. These criminal activities are very difficult to solve, hence on most occasions, their victims normally do not get justice. Because of their large number, the criminal department is overwhelmed in investigating these criminal activities. This means that there are no enough personnel who can help in investigating these criminal activities. This is a major challenge facing investigators (Lister, 2013). To solve on this situation, there is a need of hiring more personnel, and training them on the best methods of investigating this type of crime. Serious Crimes The investigation of serious crimes is also has challenges. The CID has a monopoly in this area, and it makes it difficult for other organs of the police force to demand for accountability in the manner which these criminal activities are investigated. Furthermore, the media has portrayed the investigation of these types of offences as glorious, and this limits the effectiveness of investigators. An example is the Sherlock Holmes series of investigations, where the media glorifies the activities of detective Holmes (Taylor, Fritsch and Liederbach, 2014). This is a misconception portrayed by the media. Risk Factors: Furthermore, the quality of investigation is affected by the risks that are placed on police officers to perform. This is in circumstances when there is a public outcry on the rise of insecurity in certain areas of the country. Too much pressure has the capability of affecting the quality of an investigation (Griffiths, 2014). There is also too much reliance on interviews and this is a challenge because people may lie while being interviewed. Furthermore, it is possible to categorize such kinds of evidence as hearsay by the courts. This means that they will not be admissible (Kassin et al, 2014). Investigators, also have a close relationship with criminals. This is basically because it is difficult to crack an underground crime organization without the help of criminals’ officers. This is unethical practice, because it is wrong to associate with people, that they are tasked to fight against. Detection Rates: Detection rates also present a challenge to investigation of crime. This refers to the criminal activities that have been successfully solved. This is always a political process, and the judges and the courts may be influenced. This is based on the perception of the society. Forensic Science and the Media: The emergence of the media has played a role in blurring reality, with fiction. This means that it has an influence in making some fictional activities to be reality, hence affecting the quality of investigation. Take for example, the investigative ability of Sherlock Holmes. He is a fictional character, depicted as being highly talented. Some of his skills are not realistic, and cannot be implemented. Furthermore, lack of high quality technologies plays a role in limiting the results of investigation. Debate arises in the United Kingdom, on the need of reviewing some cases that were prosecuted in 1980s, and early 1990s, with the use of technology, for purposes of solving them. Furthermore, because of inadequate skills, there is poor use of forensic technology, for purposes of determining the real culprit of a criminal offence. Poor communication of its use is also a factor affecting the quality of investigations. Conclusion There are a lot of challenges facing the investigations of criminal offences. As discussed earlier, one of the crimes that police are unable to investigate adequately are voluminous crimes. This is because of the lack of enough personnel, who can investigate these criminal activities. Furthermore, the monopoly of the CID over serious crimes makes it to be unaccountable to any policing department. In as much as these challenges exist, with proper reforms and policies, there is a possibility of overcoming them. Bibliography: BAKER, S. (2013). Has the introduction of Police and Crime Commissioners provided accountability to local people?: a Case Study in Hampshire and IOW. BEAUREGARD, E., MARTINEAU, M. (2014). No body, no crime? The role of forensic awareness in avoiding police detection in cases of sexual homicide. Journal of Criminal Justice, 42(2), 213-220. CARR-HILL, R. A., STERN, N. H. (2014). Crime, the police and criminal statistics: an analysis of official statistics for England and Wales using econometric methods. Academic Press. FISHER, B. A., FISHER, D. R. (2012). Techniques of crime scene investigation. CRC Press. GRIFFITHS, A. G. F. (2014). Mysteries of police and crime. Arthur George Frederick Griffiths. KASSIN, S. M., KUKUCKA, J., LAWSON, V. Z., DECARLO, J. (2014). Does video recording alter the behavior of police during interrogation? A mock crime-and- investigation study. Law and human behavior, 38(1), 73. LISTER, S. (2013). The new politics of the police: police and crime commissioners and the ‘operational independence’of the police. Policing, 7(3), 239-247. NEWBURN, T. (Ed.). (2012). Handbook of policing. Routledge. ROSSMO, D. K., SUMMERS, L. (2015). Routine Activity Theory in Crime Investigation. The Criminal Act: The Role and Influence of Routine Activity Theory, 19. TAYLOR, R. W., FRITSCH, E. J., LIEDERBACH, J. (2014). Digital crime and digital terrorism. Prentice Hall Press.

Eating Disorders in Children and Adolescents Essay

Childhood obesity has become a recurring theme in the news today. A variety of issues has been discussed regarding the cause of this popular issue. Emphasis is placed on parents, culture, school meals, and a number of other factors leading to obesity. Children and adolescents are not blind to the attention placed on obesity among them and their peers. If the thin bodies of magazines, TV and media weren’t enough, children now have to face the harsh realities of statistics that are constantly broadcasted in the news. This being the case, many children and adolescents have developed unhealthy means to either get thin or stay thin. Many struggle with eating disorders. Eating disorders involve a variety of descriptions of unhealthy patterns of eating. All of them involve some abnormal pattern of eating, including not eating. No matter the type or term given the disorder, they represent a serious situation and are a mental health concern. Two of the more well-known types of eating disorders are anorexia nervosa and bulimia. Both are common among youth. Anorexia Nervosa Description Sometimes just being ‘normal’ in size is not what an individual sees as normal in himself. Anorexia nervosa is an eating disorder in which being thin is not the only issue. It is characterized by starving oneself. Signs include a body weight of less than eighty-five percent the normal body weight for that specific height and age; 3 consecutive absences of a menstrual cycle; and an abnormally strong fear of gaining weight (e.g., â€Å"Eating Dis.† n.d., para. 12). A more common outward sign of anorexia is the intense fear of gaining weight. The youth may repeatedly express verbally his desire to be thin, his belief that he is fat or overweight, and a generally twisted view of own size or weight. All of this is typically coupled with an already thin body size. Use of laxatives in addition to severely limiting food intake is commonly seen. Anorexia Nervosa Cause The cause of anorexia is not one specific factor. It is widely agreed that many issues combine to lead to its development. These include social, cultural, psychological, and biological concerns. The role of neurotransmitters in anorexia is researched today. Serotonin is a neurotransmitter â€Å"known to affect appetite control, sexual and social behavior, stress responses, and mood† and â€Å"modulates feeding by producing the sensation of fullness or satiety† (Rome, 2003, p.100). A decrease in this neurotransmitter can be indicative of anorexia. There are also some indications of genetic factors involved in causing anorexia. Having a family member who suffers or has suffered from anorexia can predispose a child to development. â€Å"There are now multiple case-control studies designed to investigate the familiality of eating disorders, which demonstrate a higher rate of Anorexia nervosa in relatives of probands with anorexia nervosa† (Rome, 2003, p 101). Bulimia Description Another eating disorder common among children and adolescents is bulimia. Bulimia can actually be a subtype of anorexia. It is characterized by bingeing on food then purging the food via induced vomiting. The bingeing is considered uncontrolled and the person typically ingests much larger than normal amounts of food, sometimes secretively. Then, within an hour or two of eating, the person purges the food. This is usually done by self-induced vomiting; however, the vomiting is typically seen with misuse of laxatives, urine-producing medications, and enemas. All of these enable the individual to purge herself of the recently ingested large quantities of food. These binges occur â€Å"at least twice a week for three months or may occur as often as several times a day† (e.g., â€Å"Eating Dis.† n.d., para. 23). As a subtype of anorexia, the bulimic person is abnormally underweight. Being underweight, however, is not a prerequisite of the bulimic diagnosis. In fact, the average bulimic is of normal weight, but sees self as being overweight. Other common attitudes associated with bulimia include extreme exercise, secretive or abnormal eating habits or rituals, and irregular or absent menstrual cycles. Both bulimia and anorexia are commonly seen in individuals already suffering from anxiety and/or depression (e.g. â€Å"Eating Dis.† n.d., para. 29). Bulimia Cause As with Anorexia nervosa, a specific cause for bulimia is not known. Several factors, however, are thought to increase the likelihood of this disorder; many of these are similar to those of anorexia nervosa. Cultural and social influences on appearance and size, family problems, and mood disorders all have an effect on the development of bulimia. Gender plays a large role as well. The majority of youth suffering from both bulimia and anorexia nervosa, although more so with bulimia, are females (Fisher, 1995, p. 431). The same case study cited in the familial causes of anorexia nervosa indicates that having a family member who has previously been diagnosed with bulimia can also predispose an individual to the same behavior. Treatment Although Anorexia nervosa and Bulimia are two separate identifiable diagnoses, the treatments of these physical and mental disorders are similar. Physicians first analyze the individual’s specific overall health and possible contributing factors. The primary care doctor is the necessary authority to either treat or recommend for treatment. Possible physical effects such as malnutrition and dental issues are treated as needed. The mental and psychological treatment varies according to the child’s specific needs. Individual and family therapy, behavior modification, and cognitive therapy can all be used. Focus primarily tends toward the development of adequate coping skills, positive body image, and positive self-talk. Frequently, mood stabilizers are prescribed in conjunction with one-on-one therapy (Rome, 2003, p. 104). The family plays a key role in treating children and adolescents most significantly by the fact that parents and adult figures in the child’s life control and direct the routine of said child. In cases of severely physically compromised children, monitoring of vital signs, nutrition, and electrolyte balance by trained healthcare professionals may be necessary (Fischer, 1995, p. 435). Conclusion Eating disorders are spread across both adults and youth. As increasing attention is given the issue of childhood obesity—and as the media continues to push the preference for abnormally thin figures in beauty—the youth will suffer. They seek unhealthy means to be what culture, family, and society says is normal, accepted. Bulimia and anorexia nervosa are the result of these issues and remain common eating disorders among children and adolescents. These disorders, however, can be diagnosed and treated. Most important to the treatment of any disorder affecting children and adolescents is the role of parents or guardians. References Eating disorders in children and adolescents (n.d.) In Eating Disorders. Retrieved from http://www.lpch.org/diseasehealthinfo/healthlibrary/growth/eatdis.html. Ellen S. Rome, MD, Seth Ammerman, MD, et al. Children and adolescents with eating disorders: the state of the art. Pediatrics. 2003; 111: 98-108. Fisher M. Golden NH, Katzman DK, et al. Eating disorders in adolescents: a background paper. Adolescent Health. 1995; 16: 420-437.

The rise of Renaissance culture

The rise of Renaissance culture was predetermined by the assortment of disparate events and ideas surfacing during the end of the fourteenth and the beginning of the fifteenth centuries. The most important concept to come out of all the innovative developments of the late fourteenth century was a renewed belief in the power and the majesty of the human being. An interest to individuality was a line of demarcation between the medieval period, where God was the center, and the epoch of Renaissance.The Renaissance is viewed as culmination of a general rebirth of humanistic pursuits and a freeing of the artist from the restrictive dogma of the medieval Church. The status of art and the artist shifted significantly and our contemporary views on both are based very much on certain assumptions about the role of art in culture that were first developed during the Renaissance. It was in the Renaissance that the role of artist went from simple maker to that of creator (with individual genius) – the appellation once reserved only to God.As a consequence, art took on even greater significance becoming not only an expression of its age and its means of production but also the very embodiment of genius. Filippo Brunelleschi fairly takes the place of such a genius. It was he, the Italian architect and sculptor, who made revolutionary discoveries in architecture. This Florentine was the first and perhaps the most distinguished of the Renaissance architects. The best support for the veracity of this statement is Brunelleschi’s solution for the dome of Florence Cathedral, the building that made him most complete and representative Renaissance artist.The story of Brunelleschi’s success begins with his failure. In 1401 the competition for a pair of bronze doors for Baptistery was announced (Web Gallery of Art). This was to be one of the greatest competitions at the age, and it pitted two of Florence’s most talented young artists against each other: Fili ppo Brunelleschi and Lorenzo Ghiberti. The competition asked each artist to submit design of cast bronze around the subject of the sacrifice of Isaac. Brunelleschi lost the bid. But this perhaps initial loss was the Renaissance’s gain in that his later discoveries in architecture were to prove revolutionary.At the time of competition the Florence Cathedral was still unfinished. The problem was how to successfully bridge the enormous area of central tower without the use of flying buttresses, which were out of question because of their obvious incompatibility with the beautiful Romanesque marble exterior. Brunelleschi studied many ancient building projects in Rome such a Parthenon and suggested that a dome could in fact be built without the visual distraction created by buttressing. His answer was the implementation of classical vaulting techniques.Thus Brunelleschi’s innovative design provided further evidence of the new sensibility of Renaissance art. Brunelleschi und erstood that the principles of buttressing were useful in spreading the enormous weight of a dome over a greater expanse – thereby alleviating much of stress on the walls and foundation of the structure. He thus concluded that the tall supporting walls of the dome had to be constructed with tribunes, small offshooting extensions from the original walls, which would act as the original buttress, to disperse weight over a wider area.In this way Brunelleschi manipulated the basic tenets of medieval cathedral construction to better serve the interests of the new church. Clearly, however, it was the dome itself that created such awe among the Florentines. No structure like it had been attempted in Europe since antiquity, and never before on such an immense scale. In 1420 he began to build the Cathedral dome, a vast octagonal structure crowned by an enormous lantern designed by Brunelleschi alone.His solution was to create a dome within a dome, which would further support the exter ior weight effectively while removing the need for interior armatures or any other superfluous accessories that would distract from the simplicity of the construction. The outer dome was thus constructed as a light skin or cover, exhibiting great visual authority over the Florence skyline. The use of â€Å"spiraling courses of herringbone brickwork, iron chains and sloping masonry rings to bind the dome together, and ribs joining the shells† (King, 87) are his inventions, although owe much to his studies of Roman structures.Brunelleschi’s genius lay in his abilities to combine ancient and modern aesthetic, architectural, and engineering principles. The result was a resurgence in dome architecture, since now architects possessed both the skill and technical know-how to attempt structures which had only years before been thought impossible. In the words of Vasari, Brunelleschi â€Å"was sent by Heaven to invest architecture with new forms, after it had wandered astray f or many centuries† (Vasari, 104).The ‘new forms’ were those of Classical antiquity, which Brunelleschi applied to such building types as cathedrals and basilican churches for which there were no ancient precedents. In these schemes he was the first since antiquity to make use of the Classical orders; at the same time he employed a proportional system of his own invention, in which all units were related to a simple module, the mathematical characteristics of which informed the entire structure. Brunelleschi worked almost exclusively in Florence, and many features link his architecture with the Romanesque heritage of that city.Nevertheless, he was beyond question responsible for initiating the rediscovery of ancient Roman architecture. He understood its inherent principles and he employed them in an original manner for the building tasks of his own day. So what we may conclude from Brunelleschi’s technical breakthrough that in the best way complied with Rena issance requirements? First, it must be remembered that had it not been for the renewed interest in Classical thought and culture, it is doubtful that artist like Brunelleschi would have sought inspiration from Roman architecture such as a Pantheon.It was not that artists and architects had not been interested in such building solutions before Brunelleschi comes on the scene, but simply that most looked toward more spiritual and divine art forms. Brunelleschi’s dome is by design a stable and symmetrical structure. It possesses attributes that visually mimic the emerging Renaissance ideas of harmony and equilibrium over the obedience and superstition that had marked the previous age. In this way, the innovative dome construction situates itself as a vivid reminder of the greatest influences its creator had in his time. Works Cited PageKing, Ross Brunelleschi’s Dome: How a Renaissance Genius Reinvented Architecture, New York: Walker and Company, 2000 Vasari, Giorgio. The Lives of the Artists. Transl. by Julia Conaway Bondanella and Peter Bondanella Oxford: Oxford University Press, 1998 â€Å"Brunelleschi’s Biography† from Web Gallery of Art Retrieved Nov 7, 2006 from http://www. wga. hu/frames-e. html? /bio/b/brunelle/biograph. html â€Å"Brunelleschi’s Cupola† from Florence Art Guide Retrieved Nov 7, 2006 from http://www. mega. it/eng/egui/monu/bdd. htm â€Å"Filippo Brunelleschi† from Wikipedia Retrieved Nov 7, 2006 from http://en. wikipedia. org/wiki/Filippo_Brunelleschi

Public Key Cryptography - Free Essay Example

Sample details Pages: 6 Words: 1911 Downloads: 8 Date added: 2017/09/11 Category Advertising Essay Did you like this example? Cryptography Latika Arora , IT/06/321 Shri Balwant Institute of Technology Pallri, Sonipat, Haryana it06321. [emailprotected] com ABSTRACT The present century has been one of many scientific discoveries and technological advancements. With the advent of technology came the issue of security. As computing systems became more complicated, there was an increasing need for security. Network Security is becoming more and more crucial as the volume of data being exchanged on the Internet increases. Security is a broad topic and covers a multitude of sins. Malicious people trying to gain some benefit, get attention or to harm someone intentionally cause most security problems. Network security problems can be roughly divided into 4 closely intertwined areas. They are: A. Privacy: Privacy means that the sender and the receiver expect the confidentiality. The Transmitted message should make sense to only the intended receiver and to all others it is unintelligible. Authentication: Ensures that the sender and the receiver are who they are claiming to be B. .Data integrity: Ensure that data is not changed from source to destination. Don’t waste time! Our writers will create an original "Public Key Cryptography" essay for you Create order C.. Non-repudiation: Ensures that the sender has strong evidence that the receiver has received the message, and the receiver has strong evidence of the sender identity, strong enough such that the sender cannot deny that it has sent the message and the receiver cannot deny that it has received the message. This paper deals with cryptography, which is one of the methods to provide security. It is needed to make sure that information is hidden from anyone for whom it is not intended. It involves the use of a cryptographic algorithm used in the encryption and decryption process. It works in combination with the key to encrypt the plain text. Public key cryptography provides a method to involve digital signatures, which provide authentication and data integrity. I. INTRODUCTION The goal of cryptography is to make it possible that two people to exchange a message in such a way that other people cannot understand. There is no end that number of ways this can be done, but here we will be concerned with the methods of altering the text in such a way that the recipient can undo the alteration and discover the original text. A. Encryption and decryption The basic functionality of cryptography is to hide information. Its operation typically includes two processes: †¢ Encryption as the process of transforming information so that it is unintelligible to an intruder, and †¢ Decryption as the process of transforming the encrypted information so that it is intelligible again. Data that can be read and understood without any special measures is called plaintext or clear text. The method of disguising plaintext in such a way as to hide its substance is called encryption. Encrypting plaintext results in unreadable gibberish called cipher text. We use encryption to make sure that information is hidden from anyone for whom it is not intended, even those who can see the encrypted data. The process of reverting cipher text to its original plaintext is called decryption. [pic] Strong cryptography Cryptography can be strong or weak, as explained above. Cryptographic strength is measured in the time and resources it would require to recover the plaintext. The result of strong cryptography is cipher text that is very difficult to decipher without possession of the appropriate decoding tool. How difficult? Given all of today’s computing power and available time—even a billion computers doing a billion checks a second—it is not possible to decipher the result of strong cryptography before the end of the universe. B. How does cryptography work? A cryptographic algorithm, or cipher, is a mathematical function used in the encryption and decryption process. A cryptographic algorithm works in Combination with a key—a word, number, or phrase—to encrypt the plaintext. The same plaintext encrypts to different cipher text with different keys. The security of encrypted data is entirely dependent on two things: the strength of the cryptographic algorithm and the secrecy of the key. A cryptographic algorithm, plus all possible keys and all the protocols that make it work, comprise a cryptosystem. PGP is a cryptosystem. C. Keys use in cryptography A key is a value that works with a cryptographic algorithm to produce a specific cipher text. Keys are basically really, really, really big numbers. Key size is measured in bits; the number representing a 2048-bit key is huge. In public-key cryptography, the bigger the key, the more secure the cipher text. However, public key size and conventional cryptography’s secret key size are totally unrelated. A conventional 80-bit key has the equivalent strength of a 1024-bit public key. A conventional 128-bit key is equivalent to a 3000-bit public key. Again, the bigger the key, the more secure, but the algorithms used for each type of cryptography are very different. While the public and private keys are mathematically related, it’s very difficult to derive the private key given only the public key; however, deriving the private key is always possible given enough time and computing power. This makes it very important to pick keys of the right size; large enough to be secure, but small enough to be applied fairly quickly. Larger keys will be cryptographically secure for a longer period of time. Keys are stored in encrypted form. PGP stores the keys in two files on your hard disk; one for public keys and one for private keys. These files are called key rin gs. If you lose your private key ring you will be unable to decrypt any information encrypted to keys on that ring. D. Types of Cryptography 1. )Public key Crptography Public key cryptography is an asymmetric scheme that uses a pair of keys for encryption: a public key, which encrypts data, and a corresponding private key (secret key) for decryption. It is computationally infeasible to deduce the private key from the public key. Anyone who has a public key can encrypt information but cannot decrypt it. Only the person who has the corresponding private key can decrypt the information. Public-key cryptography is a cryptographic approach which involves the use of asymmetric key algorithms instead of or in addition to symmetric key algorithms. [pic] The asymmetric key algorithms are used to reate a mathematically related key pair: a secret private key and a published public key. Use of these keys allows protection of the authenticity of a message by creating a digital signature of a message using the private key, which can be verified using the public key. It also allows protection of the confidentiality and integrity of a message, by public key encryp tion, encrypting the message using the public key, which can only be decrypted using the private key. The primary benefit of public key cryptography is that it allows people who have no preexisting security arrangement to exchange messages securely. The need for sender and receiver to share secret keys via some secure channel is eliminated; all communications involve only public keys, and no private key is ever transmitted or shared. Some examples of public-key cryptosystems are Elgamal, RSA, Diffie-Hellman and DSA, the Digital Signature Algorithm. 2. )Private key Cryptography Public key cryptography also known as symmetric key cryptography uses a single secret key shared by sender and receiver (which must also be kept private, thus accounting for the ambiguity of the common terminology) for both encryption and decryption. To use a symmetric encryption scheme, the sender and receiver must securely share a key in advance. The Data Encryption Standard (DES) is an example of a conventional cryptosystem that is widely employed by the U. S. government. [pic] 3. ) Digital Signatures A major benefit of public key cryptography is that it provides a method for employing digital signatures. Digital signatures let the recipient of information verify the authenticity of the information’s origin, and also verify that the information was not altered while in transit. Thus, public key digital signatures provide authentication and data integrity. A digital signature also provides non-repudiation, which means that it prevents the sender from claiming that he or she did not actually send the information. These feature sare every bit as fundamental to cryptography as privacy, if not more. A digital signature serves the same purpose as a handwritten signature. However, a handwritten signature is easy to counterfeit. A digital signature is superior to a handwritten signature in that it is nearly impossible to counterfeit, plus it attests to the contents of the information as well as to the identity of the signer. Digital signatures is basically a message signed ith a senders private key can be verified by anyone who has access to the senders public key, thereby proving that the sender had access to the private key (and therefore is likely to be the person associated with the public key used), and the part of the message that has not been tampered with. [pic] 4. )Hash Function The system described above has some problems. It is slo w, and it produces an enormous volume of data—at least double the size of the original information. An improvement on the above scheme is the addition of a one-way hash function in the process. A one-way hash function takes variable-length input in this case, a message of any length, even thousands or millions of bits—and produces a fixed-length output; say, 160 bits. The hash function ensures that, if the information is changed in any way—even by just one bit—an entirely different output value is produced. PGP uses a cryptographically strong hash function on the plaintext the user is signing. This generates a fixed-length data item known as a message digest. Then PGP uses the digest and the private key to create the â€Å"signature. † PGP transmits the signature and the plaintext together. Upon receipt of the message, the recipient uses PGP to recompute the digest, thus verifying the signature. PGP can encrypt the plaintext or not; signing plaintext is useful if some of the recipients are not interested in or capable of verifying the signature. As long as a secure hash function is used, there is no way to take someone’s signature from one document and attach it to another, or to alter a signed message in any way. The slightest change to a signed document will cause the digital signature verification process to fail. Digital signatures play a major role in authenticating and validating the keys of other PGP users. II. CONCLUSION As the proverb says that â€Å" Even a crow can peck an elephant which is stuck in the mud†. Even though we are providing high security by cryptography there are many pitfalls in it also. Nothing in the world is 100% secured. Cryptography is one of the way to provide network security but it is not only the path to achieve network security. There is no gain saying the fact that cryptography plays an essential role in protecting the privacy of electronic information against threats from a variety of potential attackers. Public key cryptography, is the most important technology in modern ryptographic schemes to address issues like key management, authentication, non-repudiation and digital signature cryptosystems with smaller key lengths offer virtually no security. Symmetric-key systems offer an advantage over the public-key systems. Private keys in public-key systems are much larger. III. REFERENCES i. â€Å"Cryptography and Network Security, Principles and Prac tices† (Third Edition)-William Stallings. ii. â€Å"A Method for obtaining Digital Signatures and Public Key Cryptographic Systems. † Rivesp. R , Shamir. A and Adleman. L iii. â€Å"Multiuser Cryptography Techniques. † Diffie. W and Hellman. M