Cooling curve Essays

Cooling bend Essays Cooling bend Paper Cooling bend Paper A cooling bend is really a line diagram speaking to the adjustment in the condition of matter of a substance, either from strong to fluid or fluid to strong. In this diagram, time is normally spoken to on the x hub and temperature on the y hub. The particles in the wax in the strong state gradually begin to get more vitality when warmed and begin to move all the more quickly at a specific temperature and afterward change to fluid. At the point when it needs to change from fluid to strong, the particles in the wax begin to lose vitality and approach together till they become strong. Factors: Independent Dependant Controlled Temperature change Time taken for wax to harden Environmental change, measure of wax taken. Device: Boiling tube Beaker 250 cm3 (I 25 cm3) Thermometer extend 10i C to 110i C (I 0. 5i C) Clamp stand Bunsen burner Tripod stand Wire measure Paraffin wax Water for water shower (in recepticle) Stopwatch (I 0. 1 seconds) METHOD (GIVEN): 1) Heat a large portion of a measuring glass of water to about 90i C. 2) Clamp a bubbling cylinder with paraffin wax in it and put it in heated water with the thermometer. 3) Measure the temperature of liquid wax and start your stopwatch. 4) Record the temperature at reasonable time stretches till all the wax hardens totally. 5) Present your outcomes reasonably and decipher these as far as the ideas youve adapted up until this point. Perceptions: Amount of water (ml) Initial Temperature (Trial 1) (I C) Initial Temperature (Trial 2) (I C) Water Temperature (I C) Time stretches (s) Temperature (Trial 1) (I C) Temperature (Tria C individually, it began to go clear steadily, until it softened totally at 62. 5i C and 63. 0i C individually so, all in all, it was totally straightforward. As it begin freezing, at 48. 0i C and 50. 5i C individually, it began to pick up its unique grayish shading and it solidified totally at 50. 0i C and 53. 0i C separately, it was totally murky. Charts: Trial 1: Trial 2: ANALYSIS: From the above diagrams, we can see that the temperature of the wax in the test tube continues falling until a specific point where it turns into a steady worth and afterward keeps on falling. The particles of wax that are held together by more fragile intermolecular powers need to a specific temperature at which all the bonds can get more grounded in order to change its state. At the point when warmth is detracted from a fluid substance, the vitality provided to it drops and in this manner, the particles need more vitality to slam into one another and move far separated. In this way, the particles come nearer to one another and the intermolecular powers become more grounded. The temperature required for bonds to frame in a specific substance is the equivalent for all particles in that substance and subsequently, the temperature of the wax stays consistent all through a specific period when all bonds are shaped, changing the condition of the substance. This shows the wax utilized in the trial was an unadulterated substance as it has been demonstrated that a substance is unadulterated just if its dissolving/breaking point is a steady. The temperature fell quickly in the underlying stages in light of the fact that not many bonds or no bonds could be framed because of such a high temperature. Afterward, as the temperature drops, the quantities of bonds shaped become similarly higher and in this way, the temperature begins to fall gradually. When the entire substances hardens, all the securities have been shaped and in this way, the particles of the substance have an extremely low vitality as a result of which they cannot impact and produce heat. Hence, the temperature of the substance keeps on falling. Potential SOURCES OF ERROR: The perusing taken from the thermometer might not have been totally precise all through the investigation. As the test was led in a cooled room, this could have influenced the test. The time taken from the stopwatch wouldnt be totally exact. End: From this investigation, we can presume that the temperature required for bonds to frame in a specific substance is the equivalent for all particles in that substance. This standard applies to every unadulterated substance as all particles in an unadulterated substance are the equivalent and in this manner, they security at a similar temperature, as in this trial. A sullied substance would contain different substances and subsequently, the particles would bond at various temperatures and the bubbling/softening point wouldnt be a consistent.

Effect of Violence on Television and Video Games

Queston: Discover something in a film, network show, book, computer game, recent development, individual experience, and so forth., and expound on how it identifies with brain research. Answer: Presentation For all intents and purposes since the hour of day break of TV, its effect has been a significant worry for guardians, instructors and officials. One of the most unique concerns has been the utilization of brutality in the media just as the computer games. According to Bryant Vorderer (2013), media savagery can desensitize individuals to viciousness in reality and that, for certain individuals, watching brutality in the media gets charming and doesn't bring about the on edge excitement that is commonly expected in the wake of watching it. This investigation examines the effect of vicious films and computer games on the brain science. Impact of viciousness on TV In a vicious TV program watchers might get into the recognizable proof with a fierce character. Individuals are bound to carry on forcefully themselves when they get the opportunity to distinguish themselves in setting to a rough character. If there should arise an occurrence of kids whatever they hear or find in the media will in general affect them in a few or the other way. Learning of forceful disposition and conduct, desensitization or the expansion in the hardness for the survivors of brutality, tendency or misrepresentation of dread of turning into a casualty by certain methods for viciousness are a portion of the results which have a mental decrease among the watchers (Mller et al.2012). While these impacts reflect unfavorable results, it is the initial an expanded penchant for savage conduct that is at the center of general wellbeing worry about broadcast viciousness. The measurable connection between childrens presentation to savage depictions and their ensuing forceful con duct has been demonstrated to be more grounded than the connection between asbestos introduction and the danger of laryngeal malignancy; there is no discussion in the clinical, general wellbeing, and sociology networks about the danger of hurtful impacts from childrens presentation to media savagery. Or maybe, there is solid accord that presentation to media brutality is a huge general wellbeing worry too. Considering Ramos et al. (2013), most viciousness on TV are either glamorized or cleaned. Glamorized alludes to the way that the greater part of the savagery in the TV is performed by the most fabulous character in the show, and they don't endure regret, analysis, or punishment for the rough conduct. In excess of 33% of the viciousness is performed by alluring characters, and multiple thirds of the brutality being submitted pull off no discipline by any stretch of the imagination. Purified alludes to the disappointment of the depictions in demonstrating reasonable damages to the individual casualties. Torment and enduring which are prompt is remembered for not exactly 50% of the fierce scenes in the show. More than 33% of the vicious associations portray ridiculous and gentle negative results to the people in question, which significantly downplays the seriousness of the injury brought about by specific activities in the genuine viable world (Gunter Harrison, 2013). Subsequently the vast majority of the vicious demonstrates will in general be cleaned which demonstrates least mischief to the casualties outwardly yet it has mental impacts in different manners. Constant introduction to brutal delineations can make desensitization savagery which implies that the watchers may all the more energetically acknowledge viciousness from others and execute fierce exercises without anyone else too. The over presentation of a person to savagery, and particularly the one which is depicted in a reasonable way, may lead watchers, almost certain youngsters to accept that it is dangerous to live on earth since it is likely not a protected spot to be in (Gentile Bushman, 2012). Overestimation of the likelihood that at last there are odds of them to become casualties of brutal exercises is exceptionally expected and prompts the expanded undue pressure, strain and nervousness. Shows like CSI: Crime Scene Investigations, House M.D are shows which have been considered to have consequences for watchers. Notwithstanding, the impacts can incorporate learning and having fun however not get contrarily influenced or may bring about mental impacts which incorporate fi erce streaks, pressure of being a casualty. Impact of brutal computer games The approach of computer games like the Honorable obligation and Excellent Theft Auto are a lot of brutal, yet as the idea of video gaming viciousness is new, it is gradually picking up pace when contrasted with the media savagery impacts. In spite of the fact that the whole idea brings up numerous issues as the computer game client isn't just review it but at the same time is legitimately included by playing it. Around 90-95% of youths are computer game players, and utilize different hotspots for it. A large portion of the computer games have segment of savagery in it. This has offered ascend to meta-diagnostic audits that show the negative impacts of computer games. As indicated by Shaffer Kipp (2013), open to rough computer games is a significant hazard factor which prompts the expansion in hostility, inconsiderate conduct, forceful cognizance, diminished sympathy and master social conduct. This is because of increment in the contrary contemplations with the individual who is playing such computer games all the more regularly. Perhaps the most serious issue with vicious computer games is that they dishearten players from practicing discretion inside them. For instance in Grand burglary Auto computer games the players can take vehicles, execute different characters in the game including police authorities, in such circumstances players are frequently remunerated as opposed to being rebuffed (Greitemeyer, Traut-Mattausch Osswald, 2012). Not many mental characteristics appear to stay stable from youth into adulthood, and less yet have been appeared to complete the expectation of progress or disappointment in ones life. Another difficult that influences the brain science of the youngsters is that the players are bound to relate to a vicious character (Mentzoni et al.2011). In the event that the game is first individual shooter, at that point the player have a similar perception viewpoint as the executioner. Also, if the game is a third individual, the player will in general include in the controlling the activities of the fierce character from an increasingly inaccessible visual viewpoint. Savage games legitimately reward rough conduct, by including compensating focuses to the player for getting into next level. In certain games, players get verbal applauding for the way the play. These impacts will in general go unnoticed as individuals don't comprehend the mental impact of the computer game brutality, as they see just the natural procedure (Montag et al.2012). There are acceptable hypothetical motivations to accept that brutal computer games are considerably more hurtful than rough TV projects or motion pictures. Forceful conduct is multi decided with introduction of rough computer games, then again, even little impacts and the impact of the savage computer games is little to medium in its impact size can have an extremely awful outcomes on the cultural level when numerous individuals are uncovered. Notwithstanding, kids are bound to copy the activities of the characters with whom they can recognize without any problem. In brutal computer games players being the characters get the chance to pick the weapons too, and the procedure requires dynamic support rather than simply uninvolved perception. The reiteration of the procedure builds the learning among the players, which will in general give a conduct practice to the players (Greenfield, 2014). End The examination includes the impacts of fierce games and TV programs on players and watchers individually. Survey brutal TV programs brings about the putting away of a perceptual and psychological portrayal of the occasion with in the memory. It is brought into the people thought. The conversation likewise makes reference to that among the populace, kids are bound to get affected mentally when they play fierce games or watch savage network shows. It is likewise uncovered that every one of these variables will in general get into mind which may likewise turn out as savage streaks or additionally in the structure pressure and strains of getting misled. For better understanding well known computer games like Call of Duty and Great Theft Auto and network shows CSI: Crime Scene Investigations, House M.D are taken as contextual investigation. References Greenfield, P. M. (2014).Mind and media: The impacts of TV, computer games, and PCs. Brain research Press. Montag, C., Weber, B., Trautner, P., Newport, B., Markett, S., Walter, N. T., ... Reuter, M. (2012). Does exorbitant play of brutal first-individual shooter-computer games hose mind action in light of passionate stimuli?.Biological psychology,89(1), 107-111. Mentzoni, R. A., Brunborg, G. S., Molde, H., Myrseth, H., Skouvere, K. J. M., Hetland, J., Pallesen, S. (2011). Tricky computer game use: evaluated predominance and relationship with mental and physical health.Cyberpsychology, conduct, and social networking,14(10), 591-596. Greitemeyer, T., Traut-Mattausch, E., Osswald, S. (2012). The most effective method to enhance negative impacts of savage computer games on collaboration: Play it helpfully in a team.Computers in Human Behavior,28(4), 1465-1470. Shaffer, D., Kipp, K. (2013).Developmental brain research: Childhood and youth. Cengage Learning. Gentile, D. A., Bushman, B. J. (2012). Rethinking media viciousness impacts utilizing a hazard and versatility way to deal with comprehension aggression.Psychology of Popular Media Culture,1(3), 138. Gunter, B., Harrison, J. (2013).Violence on TV: An examination of sum, nature, area and starting point of viciousness. Routledge. Ramos, R. A., Ferguson, C. J., Frailing, K., Romero-Ramirez, M. (2013). Easily numb or at this time another film? Media savagery introduction doesn't lessen watcher sympathy for survivors of genuine brutality among essentially Hispanic viewers.Psychology of Popular Media Culture,2(1), 2. Mller, I., Krah, B., Busching, R., Krause, C. (2012). Adequacy of a mediation to diminish the utilization of media savagery and animosity: An experimen

HOW TO Generate A QR Code Using Goo.gl

HOW TO Generate A QR Code Using Goo.gl Make Money Online Queries? Struggling To Get Traffic To Your Blog? Sign Up On (HBB) Forum Now!HOW TO: Generate A QR Code Using Goo.glUpdated On 19/02/2020Author : Pradeep KumarTopic : GuidesShort URL : http://hbb.me/2ozeLyw CONNECT WITH HBB ON SOCIAL MEDIA Follow @HellBoundBlogHope you guys are aware about the public launch of Googles URL Shortener service Goo.gl. Goo.gl has features like automatic spam detection and it has nearly 100% uptime since their initial launch. You can use your Google account to view URL history, traffic sources, referrers and visitor profiles for countries, browsers and platforms.I came to know Goo.gl has an awesome Easter Egg which instantly turns any link into a QR Code. A QR Code is a matrix barcode (or 2D code), readable by QR scanners, mobile phones with a camera, and smartphones. You can easily create it using this simple URL tweak. Earlier also we were able to generate QR codes using Goo.gl, but that was not the official way, and now since Goo.gl is live, we can easily generate them.How To Create QR Code Using Goo.glReally simple, just go to Goo.gl and shorten the URL.Now add .qr to the end of it.For example, the shortened URL for HellBound Bloggers is http://goo.gl/A15k. Now add .qr to the URL, i.e., http://goo.gl/A15k.qr. Now it will display the following QR code.Also check the Konami Easter egg code for Google Docs.Whats the big deal? Whats the use of this?These QR codes are great for mobile use. Google has been using them a lot for stuffs like easy installation of Android apps.READHOW TO: Develop Simple Web Browser Using C# [With URL Navigating]

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VoIP Security Internet - Free Essay Example

Sample details Pages: 21 Words: 6159 Downloads: 4 Date added: 2017/06/26 Category Statistics Essay Did you like this example? End to end VoIP security Introduction Don’t waste time! Our writers will create an original "VoIP Security Internet" essay for you Create order User communications applications are in high demand in the Internet user community. Two classes of such applications are of great importance and attract interest by many Internet users: collaboration systems and VoIP communication systems. In the first category reside systems like ICQ , MSN Messenger and Yahoo! Messenger while in the latter, systems like Skype and VoipBuster are dominating among the public VoIP clients. In the architecture plane, collaboration systems form a distributed network where the participants communicate with each other and exchange information. The data are either routed from the source through a central server to the recipient or the two clients communicate directly. The participants in such networks are both content providers and content requestors . On the other hand, the data communication path in the VoIP systems is direct between the peers, without any involvement of the service network in the data exchange path with some exceptions like Skypes superno de communications. Data are carried over public Internet infrastructures like Ethernets, WiFi hotspots or wireless ad hoc networks. Security in these networks is a critical issue addressed in several different perspectives in the past. In this assignment I focus on cryptographic security implementation in VoIP. Security is implemented dynamically in cooperation by the two (or more) peers with no prior arrangements and requirements, like out of band exchanged keys, shared secrets etc. Ease of use (simplicity), user friendliness (no special knowledge from the user side) and effectiveness (ensuring confidentiality and integrity of the applications) combined with minimal requirements on end user devices are the goals achieved by our approach. We leverage security of user communications, meeting all the above requirements, by enhancing the applications architecture with VoIPSec security elements. Over the past few years, Voice over IP (VoIP) has become an attractive alternative to more traditional forms of telephony. Naturally, with its in-creasing popularity in daily communications, re-searchers are continually exploring ways to improve both the efficiency and security of this new communication technology. Unfortunately, while it is well understood that VoIP packets must be encrypted to ensure confidentiality, it has been shown that simply encrypting packets may not be sufficient from a privacy standpoint. For instance, we recently showed that when VoIP packets are first compressed with variable bit rate (VBR) encoding schemes to save bandwidth, and then encrypted with a length preserving stream cipher to ensure confidentiality, it is possible to determine the language spoken in the encrypted conversation. As surprising as these findings may be, one might argue that learning the language of the speaker (e.g., Arabic) only affects privacy in a marginal way. If both endpoints of a VoIP call are known (for example, Mexico City and Madrid), then one might correctly conclude that the language of the conversation is Spanish, without performing any analysis of the traffic. In this work we show that the information leaked from the combination of using VBR and length preserving encryption is indeed far worse than previously thought. VOIP This assignment is about security, more specifically, about protecting one of your most precious assets, your privacy. We guard nothing more closely than our words. One of the most important decisions we make every day is what we will say and what we wont. But even then its not only what we say, but also what someone else hears, and who that person is. Voice over IP- the transmission of voice over traditional packet-switched IP networksis one of the hottest trends in telecommunications. Although most computers can provide VoIP and many offer VoIP applications, the term voice over IP is typically associated with equipment that lets users dial telephone numbers and communicate with parties on the other end who have a VoIP system or a traditional analog telephone. (The sidebar, Current voice-over-IP products, de-scribes some of the products on the market today.) As with any new technology, VoIP introduces both opportunities and problems. It offers lower cost and greater flexibility for an enterprise but presents significant security challenges. Security administrators might assume that because digitized voice travels in packets, they can simply plug VoIP components into their already se-cured networks and get a stable and secure voice net-work. Unfortunately, many of the tools used to safeguard todays computer networksfirewalls, network address translation (NAT), and encryptiondont work as is in a VoIP network. Although most VoIP components have counterparts in data networks, VoIPs performance demands mean you must supplement ordinary network software and hardware with special VoIP components. Integrating a VoIP system into an already congested or overburdened network can be disastrous for a companys technology infra-structure. Anyone at- tempting to construct a VoIP network should therefore first study the procedure in great detail. To this end, weve outlined some of the challenges of introducing appropriate security measures for VoIP in an enterprise. End-to-End Security IN this assignment I am going to describe the end-to-end security and its design principle that one should not place mechanisms in the network if they can be placed in end nodes; thus, networks should provide general services rather than services that are designed to support specific applications. The design and implementation of the Internet followed this design principle well. The Internet was designed to be an application-agnostic datagram de-livery service. The Internet of today isnt as pure an implementation of the end-to-end design principle as it once was, but its enough of one that the collateral effects of the network not knowing whats running over it are becoming major problems, at least in the minds of some observers. Before I get to those perceived problems, Id like to talk about what the end-to-end design principle has meant to the Internet, technical evolution, and society. The Internet doesnt care what you doits job is just to deliver the bits, stupid (in the words of David Isenberg in his 1997 paper, Rise of the Stupid Network2). The bits could be part of an email message, a data file, a photograph, or a video, or they could be part of a denial-of-service attack, a malicious worm, a break-in attempt, or an illegally shared song. The Net doesnt care, and that is both its power and its threat. The Internet (and by this, I mean the Arpanet, the NSFNet, and the networks of their successor commercial ISPs) wasnt designed to run the World Wide Web. The Internet wasnt designed to run Google Earth. It was designed to support them even though they did not exist at the time the foundations of the Net were designed. It was designed to support them by being designed to transport data without caring what it was that data represented. At the very first, the design of TCP/IP wasnt so flexible. The initial design had TCP and IP within a single protocol, one that would only deliver data reliably to a destination. But it was realized that not all applications were best served by a protocol that could only deliver reliable data streams. In particular, timely delivery of information is more important than reliable delivery when trying to support interactive voice over a network if adding reliability would, as it does, increase delay. TCP was split from IP so that the application running in an end node could determine for itself the level of reliability it needed. This split created the flexibility that is currently being used to deliver Skypes interactive voice service over the same network that CNN uses to deliver up-to-the-minute news headlines and the US Patent and Trademark office uses to deliver copies of US patents. Thus the Internet design, based as it was on the end-to-end principle, became a generative facility. Unlike the traditional phone system, in which most new applications must be installed in the phone switches deep in the phone net-work, anyone could create new applications and run them over the Internet without getting permission from the organizations that run the parts of the Net. This ability was exploited with irrational exuberance4 during the late 1990s Internet boom. But, in spite of the hundreds of billions of dollars lost by investors when the boom busted, the number of Internet users and Web sites, the amount of Internet traffic, and the value of Internet commerce have continued to rise, and the rate of new ideas for Internet-based services hasnt no- ticeably diminished. Security and privacy in an end-to-end world The end to end arguments paper used se-cure transmission of data as one reason that an end-to-end design was required. The paper points out that network-level or per-link encryption doesnt actually provide assurance that a file that arrives at a destination is the same as the file that was sent or that the data went unobserved along the path from the source to the destination. The only way to ensure end-to-end data integrity and confidentiality is to use end-to-end encryption. Thus, security and privacy are the responsibilities of the end nodes. If you want to ensure that a file will be transferred without any corruption, your data-transfer application had better include an integrity check, and if you didnt want to allow anyone along the way to see the data itself, your application had better encrypt it before transmitting it. There are more aspects to security on a network than just data encryption. For example, to ensure that communication over the net-work is reliable, the network itself needs to be secure against attemptspurposeful or accidentalto disrupt its operation or redirect traffic away from its intended path. But the original Internet design didnt include protections against such attacks. Even if the network is working perfectly, you need to actually be talking to the server or person you think you are. But the Internet doesnt pro-vide a way, at the network level, to assure the identities of its users or nodes. You also need to be sure that the message your computer re receives isnt designed to exploit weaknesses in its software (such as worms or viruses) or in the ways that you use the Net. Protection against such things is the end systems responsibility. Note that there is little that can be done in the Net or in your end system to protect your privacy from threats such as the government demanding the records of your use of Net-based services such as Google, which collect information about your network usage. Many of todays observers assume that the lack of built-in protections against attacks and the lack of a se-cure way to identify users or nodes was a result of an environment of trust that prevailed when the original Internet design and protocols were developed. If you trusted the people on the Net, there was no need for special defensive functions. But a few people who were at the scene have told me that such protections were actively discouraged by the primary sponsor of the early Internetthat is to say, the US military wasnt all that interested in having good nonmilitary security, maybe because it might make its job harder in the future. Whatever the reason, the Internet wasnt designed to provide a secure environment that included protection against the malicious actions of those who would disrupt it or attack nodes or services provided over it. End-to-end security is not dead yet, but it is seriously threatened, at least at the network layer. NATs and firewalls interfere with some types of end-to-end encryption technology. ISPs could soon be required by regulations to, by default, filter the Web sites and perhaps the protocols that their customers can access. Other ISPs want to be able to limit the protocols that their customers can access so that the ISP can give service providers an incentive to pay for the customers use of their linesthey dont see a way to pay for the net-work without this ability. The FBI has asked that it be able to review all new Internet services for tapability before theyre deployed, and the FCC has hinted that it will support the request If this were to happen, applications such as Skype that use end-to-end encryption could be outlawed as inconsistent with law enforcement needs. Today, its still easy to use end-to-end encryption as long as its HTTPS, but that might be short-lived. It could soon reach the point that the use of end-to-end encryption, without which end-to-end security cant exist, will be seen as an antisocial act (as a US justice department official once told me). If that comes to be the case, end-toend security will be truly dead, and we will all have to trust functions in the network that we have no way of knowing are on our side. What is VoIP end to end security? Achieving end-to-end security in a voice-over-IP (VoIP) session is a challenging task. VoIP session establishment involves a jumble of different protocols, all of which must inter-operate correctly and securely. Our objective in this paper is to present a structured analysis of protocol inter-operation in the VoIP stack, and to demonstrate how even a subtle mismatch between the assumptions made by a protocol at one layer about the protocol at another layer can lead to catastrophic security breaches, including complete removal of transport-layer encryption. The VoIP protocol stack is shown in figure 1. For the purposes of our analysis, we will divide it into four layers: signaling, session description, key exchange and secure media (data) transport. This division is quite natural, since each layer is typically implemented by a separate protocol. Signaling is an application-layer (from the viewpoint of the underlying communication network) control mechanism used for creating, modifying and terminating VoIP sessions with one or more participants. Signaling protocols include Session Initiation Protocol (SIP) [27], H.323 and MGCP. Session description protocols such as SDP [20] are used for initiating multimedia and other sessions, and often include key exchange as a sub-protocol. Key exchange protocols are intended to provide a cryptographically secure way of establishing secret session keys between two or more participants in an untrusted environment. This is the fundamental building block in se-cure session establishment. Security of the media transport layerthe layer in which the actual voice datagrams are transmitteddepends on the secrecy of session keys and authentication of session participants. Since the established key is typically used in a symmetric encryption scheme, key secrecy requires that nobody other than the legitimate session participants be able to distinguish it from a random bit-string. Authentication requires that, after the key exchange protocol successfully completes, the participants respective views of sent and received messages must match (e.g., see the notion of matching conversations in [8]). Key ex-change protocols for VoIP sessions include SDPs Security DEscriptions for Media Streams (SDES) , Multimedia Internet KEYing (MIKEY) a nd ZRTP [31]. We will analyze all three in this paper. Secure media transport aims to provide confidentiality, message authentication and integrity, and replay protection to the media (data) stream. In the case of VoIP, this stream typically carries voice datagrams. Confidentiality means that the data under encryption is indistinguishable from random for anyone who does not have the key. Message authentication implies that if Alice receives a datagram apparently sent by Bob, then it was indeed sent by Bob. Data integrity implies that any modification of the data in transit We show how to cause the transport-layer SRTP protocol to repeat the keystream used for datagram encryption. This enables the attacker to obtain the xor of plaintext datagrams or even to completely decrypt them. The SRTP keystream is generated by using AES in a stream cipher-like mode. The AES key is generated by applying a pseudo-random function (PRF) to the session key. SRTP, however, does not add any session-specific randomness to the PRF seed. Instead, SRTP assumes that the key exchange protocol, executed as part of RTP session establishment, will en-sure that session keys never repeat. Unfortunately, S/MIME-protected SDES, which is one of the key ex-change protocols that may be executed prior to SRTP, does not provide any replay protection. As we show, a network-based attacker can replay an old SDES key establishment message, which will cause SRTP to re-peat the keystream that it used before, with devastating consequences. This attack is confirmed by our analysis of the libsrtp implementation. We show an attack on the ZRTP key exchange protocol that allows the attacker to convince ZRTP session participants that they have lost their shared secret. ZID values, which are used by ZRTP participants to retrieve previously established shared secrets, are not authenticated as part of ZRTP. Therefore, an attacker can initiate a session with some party A under the guise of another party B, with whom A previously established a shared secret. As part of session establishment, A is supposed to verify that B knows their shared secret. If the attacker deliberately chooses values that cause verification to fail, A will decidefollowing ZRTP specificationthat B has forgotten the shared secret. The ZRTP specification explicitly says that the protocol may proceed even if the set of shared secrets is empty, in which case the attacker ends up sharing a key with A who thinks she shares this key with B. Even if the participants stop the protocol after losing their shared secrets, but are using VoIP devices without displays, they cannot confirm the computed key by voice and must stop communicating. In this case, the attack becomes a simple and effective denial of service. Our analysis of ZRTP is supported by the AVISPA formal analysis tool . We show several minor weaknesses and potential vulnerabilities to denial of service in other protocols. We also observe that the key derived as the result of MIKEY key exchange cannot be used in a standard cryptographic proof of key exchange security (e.g., ). Key secrecy requires that the key be in-distinguishable from a random bitstring. In MIKEY, however, the joint Diffie-Hellman value derived as the result of the protocol is used directly as the key. Membership in many Diffie-Hellman groups is easily checkable, thus this value can be distinguished from a random bitstring. Moreover, even hashing the Diffie-Hellman value does not allow the formal proof of security to go through in this case, since the hash function does not take any random inputs apart from the Diffie-Hellman value and cannot be viewed as a randomness extractor in the proof. (This observation does not immediately lead to any attacks.) While we demonstrate several real, exploitable vulnerabilities in VoIP security protocols, our main contribution is to highlight the importance of analyzing protocols in con-text rather than in isolation. Specifications of VoIP protocols tend to be a mixture of informal prose and pseudocode, with some assumptionsespecially those about the protocols operating at the other layers of the VoIP stackare left implicit and vague. Therefore, our study has important lessons for the design and analysis of security protocols in general. The rest of the paper is organized as follows. In section 2, we describe the protocols, focusing on SIP (signaling), SDES, ZRTP and MIKEY (key exchange), and SRTP (transport). In section 3, we describe the attacks and vulnerabilities that we discovered. Related work is in section 4, conclusions are in section 5. VoIP security different from normal data network security To understand why security for VoIP differs from data network security, we need to look at the unique constraints of transmitting voice over a packet network, as well as the characteristics shared by VoIP and data networks. Packet networks depend on many configurable parameters: IP and MAC (physical) addresses of voice terminals and addresses of routers and firewalls. VoIP networks add specialized software, such as call managers, to place and route calls. Many network parameters are established dynamically each time a network component is restarted or when a VoIP telephone is restarted or added to the net-work. Because so many nodes in a VoIP network have dynamically configurable parameters, intruders have as wide an array of potentially vulnerable points to attack as they have with data networks. But VoIP systems have much stricter performance constraints than data networks, with significant implications for security. Threats for VoIP VoIP security threats contain Eavesdropping, Denial of Service, Session Hijacking, VoIP Spam, etc. For preventing these threats, there are several VoIP standard protocols. And we discuss this in Section 3. Eavesdropping VoIP service using internet technology is faced with an eavesdropping threat, in which is gathering call setting information and audio/voice communication contents illegally. Eavesdropping can be categorized largely by eavesdropping in a LAN(Local Area Network) environment, one in a WAN( Wide Area Network) environment, one through a PC(Personal Computer) hacking, etc. Denial of Service Denial of Service is an attack, which makes it difficult for legitimate users to take telecommunication service regularly. Also it is one of threats, which are not easy to solve the most. Since VoIP service is based on internet technology, it also is exposed to Denial of Service. Denial of Service in VoIP service can be largely divided into system resource exhaustion, circuit This work was supported by the IT RD program of MIC/IITA resourceexhaustion,VoIP communication interruption/blocking, etc. Session Hijacking Session Hijacking is an attack, which is gathering the communication session control between users through spoofing legitimate users, and is interfering in their communication, as a kind of man-in-the-middle attack. Session Hijacking in VoIP communication can be categorized largely by INVITE session hijacking, SIP Registration hijacking, etc. VoIP Spam VoIP Spam is an attack, which is interrupting, and violating user privacy through sending voice advertisement messages, and also makes VMS(Voice Mailing System) powerless. It can be categorized by Call Spam, IM(Instant Messaging) Spam, Presence Spam, etc. Security trade-offs Trade-offs between convenience and security are routine in software, and VoIP is no exception. Most, if not all, VoIP components use integrated Web servers for configuration. Web interfaces can be attractive, easy to use, and inexpensive to produce because of the wide availability of good development tools. Unfortunately, most Web development tools focus on features and ease of use, with less attention paid to the security of the applications they help produce. Some VoIP device Web applications have weak or no access control, script vulnerabilities, and inadequate parameter validation, resulting in privacy and DoS vulnerabilities. Some VoIP phone Web servers use only HTTP basic authentication, meaning servers send authentication information without encryption, letting anyone with network access obtain valid user IDs and passwords. As VoIP gains popularity, well inevitably see more administrative Web applications with exploitable errors. The encryption process can be unfavorable to QoS Unfortunately, several factors, including packet size expansion, ciphering latency, and a lack of QoS urgency in the cryptographic engine can cause an excessive amount of latency in VoIP packet delivery, leading to degraded voice quality. The encryption process can be detrimental to QoS, making cryptodevices severe bottlenecks in a VoIP net-work. Encryption latency is introduced at two points. First, encryption and decryption take a nontrivial amount of time. VoIPs multitude of small packets exacerbates the encryption slowdown because most of the time consumed comes as overhead for each packet. One way to avoid this slowdown is to apply algorithms to the computationally simple encryption voice data before packetization. Although this improves throughput, the proprietary encryption algorithms used (fast Fourier-based encryption, chaos-bit encryption, and so on) arent considered as secure as the Advanced Encryption Standard,16 which is included in many IPsec implementations. AESs combination of speed and security should handle the demanding needs of VoIP at both ends. following general guidelines, recognizing that practical considerations might require adjusting them: Put voice and data on logically separate networks. You should use different subnets with separate RFC 1918 address blocks for voice and data traffic and separate DHCP servers to ease the incorporation of intrusion-detection and VoIP firewall protection. At the voice gateway, which interfaces with the PSTN, disallow H.323, SIP, or Media Gateway Control Protocol (MGCP) connections from the data network. As with any other critical network management component, use strong authentication and access control on the voice gateway system. Choose a mechanism to allow VoIP traffic through firewalls. Various protocol dependent and independent solutions exist, including ALGs for VoIP protocols and session border controllers. Stateful packet filters can track a connections state, denying packets that arent part of a properly originated call. Use IPsec or Secure Socket Shell (SSH) for all remote management and auditing access. If practical, avoid using remote management at all and do IP PBX access from a physically secure system. Use IPsec tunneling when available instead of IPsec transport because tunneling masks the source and destination IP addresses, securing communications against rudimentary traffic analysis (that is, determining whos making the calls). If performance is a problem, use encryption at the router or other gateway to allow IPsec tunneling. Be-cause some VoIP end points arent computationally powerful enough to perform encryption, placing this Recent studies indicate that the greatest contributor to the encryption bottleneck occurs at the cryptoengine scheduler, which often delays VoIP packets as it processes larger data packets.17 This problem stems from the fact that cryptoschedulers are usually first-in first-out (FIFO) queues, inadequate for supporting QoS requirements. If VoIP packets arrive at the encryption point when the queue already contains data packets, theres no way they can usurp the less time-urgent traffic. Some hardware manufacturers have proposed (and at least one has implemented) solutions for this, including QoS reordering of traffic just before it reaches the cryptoengine.18 But this solution assumes that the cryptoengines output is fast enough to avoid saturating the queue. Ideally, youd want the cryptoengine to dynamically sort incoming traffic and force data traffic to wait for it to finish processing the VoIP packets, even if these packets arrive later. However, this solution adds considerable over head to a process most implementers like to keep as light as possible. Another option is to use hardware-implemented AES encryption, which can improve throughput significantly. Past the cryptoengine stage, the system can perform further QoS scheduling on the encrypted packets, provided they were encrypted using ToS preservation, which copies the original ToS bits into the new IPsec header. Virtual private network (VPN) tunneling of VoIP has also become popular recently, but the congestion and bottlenecks associated with encryption suggest that it might not always be scalable. Although researchers are making great strides in this area, the hardware and soft-ware necessary to ensure call quality for encrypted voice traffic might not be economically or architecturally vi-able for all enterprises considering the move to VoIP. Thus far, weve painted a fairly bleak picture of VoIP security. We have no easy one size fits all solution to the issues weve discussed in this article. Decisions to use VPNs instead of ALG-like solutions or SIP instead of H.323 must depend on the specific nature of both the current network and the VoIP network to be. The technical problems are solvable, however, and establishing a secure VoIP implementation is well worth the difficulty. To implement VoIP securely today, start with the following general guidelines, recognizing that practical considerations might require adjusting them: Put voice and data on logically separate networks. You should use different subnets with separate RFC 1918 address blocks for voice and data traffic and separate DHCP servers to ease the incorporation of intrusion-detection and VoIP firewall protection. At the voice gateway, which interfaces with the PSTN, disallow H.323, SIP, or Media Gateway Control Protocol (MGCP) connections from the data network. As with any other critical network management component, use strong authentication and access control on the voice gateway system. Choose a mechanism to allow VoIP traffic through firewalls. Various protocol dependent and independent solutions exist, including ALGs for VoIP protocols and session border controllers. Stateful packet filters can track a connections state, denying packets that arent part of a properly originated call. Use IPsec or Secure Socket Shell (SSH) for all remote management and auditing access. If practical, avoid using remote management at all and do IP PBX access from a physically secure system. Use IPsec tunneling when available instead of IPsec transport because tunneling masks the source and destination IP addresses, securing communications against rudimentary traffic analysis (that is, determining whos making the calls). If performance is a problem, use encryption at the router or other gateway to allow IPsec tunneling. Be-cause some VoIP end points arent computationally powerful enough to perform burden at a central point ensures the encryption of all VoIP traffic emanating from the enterprise network. Newer IP phones provide AES encryption at reason-able cost. Look for IP phones that can load digitally (cryptographically) signed images to guarantee the integrity of the software loaded onto the IP phone. Avoid softphone systems (see the sidebar) when security or privacy is a concern. In addition to violating the separation of voice and data, PC-based VoIP applications are vulnerable to the worms and viruses that are all too common on PCs. Consider methods to harden VoIP platforms based on common operating systems such as Windows or Linux. Try, for example, disabling unnecessary services or using host-based intrusion detection methods. Be especially diligent about maintaining patches and current versions of VoIP software. Evaluate costs for additional power backup systems that might be required to ensure continued operation during power outages. Give special consideration to E-91 1 emergency services communications, because E-911 automatic location service is not always available with VoIP. VoIP can be done securely, but the path isnt smooth. It will likely be several years before standards issues are settled and VoIP systems become mainstream. Until then, organizations must proceed cautiously and not assume that VoIP components are just more peripherals for the local network. Above all, its important to keep in mind VoIPs unique requirements, acquiring the right hardware and software to meet the challenges of VoIP security. Methods for VoIP end to end security Voice over IP (VoIP) security where security design patterns may prove exceedingly useful. Internet telephony or VoIP has grown in importance and has now passed the tipping point in 2005 U.S. companies bought more VoIP phones than ordered new POTS lines. However, with the powerful convergence of software-based VoIP to enable new functionality to store, copy, combine with other data, and distribute over the Internet also comes security problems that need to be solved in standard ways in order to ensure interoperability. This is further complicated by the fact that various vendors competing for market share currently drive VoIP security. Given the importance of VoIP security, we are only aware of only two other efforts for VoIP security design patterns, a chapter within and an unpublished M.S. thesis supervised by Eduardo Fernandez of Florida Atlantic University. Figure 1. VoIP Infrastructure Vulnerabilities NIST released a report on VoIP security in January 2005 . This report elaborates on various aspects of securing VoIP and the impact of such measures on call performance. The report argues that VoIP performance and security are not seamlessly compatible; in certain areas they are orthogonal. We briefly review this report and group VoIP infrastructure threats into three categories as depicted in Figure 1: (1) Protocol (2) Implementation and (3) Management Quality of Service (QoS) Issues A VoIP call is susceptible to latency, jitter, and packet loss. ITU-T recommendation G.114 has established 150 ms as the upper limit on one-way latency for domestic calls. If Goodes latency budget is considered, very little time ( 29 ms) is left for encryption/decryption of voice traffic. QoS-unaware network elements such as routers, firewalls, and Network Address Translators (NAT) all contribute to jitter (no uniform packet delays). Use of IPsec both contributes to jitter and reduces the effective bandwidth. VoIP is sensitive to packet loss with tolerable loss rates of 1-3%; however, forward error correction schemes can reduce loss rates. Signaling and Media Protocol Security SIP (Session Initiation Protocol) (RFC 3261) and H.323 are the two competing protocols for VoIP signaling. H.323 is an ITU-T umbrella of protocols that supports secure RTP (SRTP) (RFC 3711) for securing media traffic, and Multimedia Internet Keying (MIKEY) (RFC 3830) for key exchange. SIP supports TLS and S/MIME for signaling message confidentiality and SRTP for media confidentiality. Firewalls and NATs RTP is assigned a dynamic port number that presents a problem for firewall port management. A firewall has to be made aware of the ports on which the media will flow. Thus a stateful and application-aware firewall is necessary. However, if a client is behind a NAT, call establishment signaling messages transmit the IP address and RTP port number that is not globally reachable. NAT traversal protocols like STUN (RFC 3489), TURN (RFC 2026), and ICE (14) are necessary to establish a globally routable address for media traffic. For protocols that send call setup messages via UDP, the intermediate signaling entity must send to the same address and port from which the request arrived. Encryption and IPsec IPsec is preferred for VoIP tunneling across the Internet, however, it is not without substantial overhead. When IPsec is used in tunnel mode, the VoIP payload to packet size ratio for a payload of 40 bytes and RTP/UDP headers drops to ~30%. The NIST solution to avoid queuing bottlenecks at routers due to encryption is to perform encryption/decryption solely at endpoints. SRTP and MIKEY are specified for encrypting media traffic and establishing session keys respectively. Categorizing VoIP Threats The threats faced by a VoIP are similar to other applications including: unwanted communication (spam), privacy violations (unlawful intercept), impersonation (masquerading), theft-of-service, and denial-of-service. Table 1 groups these threats into protocol, implementation, and management categories. Protocol Signaling, MediaConfidentiality, Integrity end-to-end protection as well as hop-by- hop (Proxies might be malicious) Configuration, Confidentiality, Integrity most VoIP devices are managed remotely Identity Assertion Users concerned about whether they are talking to the real entity as opposed to a phished entity Reputation Management Implementation Buffer Overflow, Insecure Bootstrapping. Management Access Control protection against unauthorized access to VoIP servers and gateways Power Failures Table 1. Categorizing VoIP Threats Secure VoIP call The Secure VoIP call pattern hides the meaning of messages by performing encryption of calls in a VoIP environment. Context Two or more subscribers are participating in a voice call over a VoIP channel. In public IP networks such as the Internet, it is easy to capture the packets meant for another user. Problem When making or receiving a call, the transported voice packets between the VoIP network nodes are exposed to interception. How to prevent attackers from listening to a voice call conversation when voice packets are intercepted on public IP networks? The solution will be affected by the following forces: Packets sent in a public network are easy to intercept and read or change. We need a way to hide their contents. The protection method must be transparent to the users and easy to apply. The protection method should not significantly affect the quality of the call. Solution To achieve confidentiality we use encryption and decryption of VoIP calls. Implementation In cases where performance is an important issue, symmetric algorithms are preferred. Such algorithms require the same cryptographic key (a shared secret key) on both sides of the channel. If the IPSec standard is used, it is necessary for participants in a call (i.e. Caller and Callee) to agree previously on a data encryption algorithm (e.g. DES, 3DES, AES) and on a shared secret key. The Internet Key Exchange (IKE) protocol is used for setting up the IPSEC connections between terminal devices. The caller encrypts the voice call with the secret key and sends it to the remote user. The callee decrypts the voice call and recovers the original voice packets. Additionally, the Secure Real Time Protocol (SRTP) can be used for encrypting media traffic and the Multimedia Internet KEYing (MIKEY) for exchanging keying materials in VoIP. If public key cryptography is used, the callee must obtain the callers public key before establishing a connection. The caller encrypts the voice call with the callees public key and sends it to her. The callee decrypts the voice call and recovers the original voice packets. The class diagram of Figure 4 shows a Secure-channel communication in VoIP (adapted from the Cryptographic Metapattern in).This model uses the Strategy pattern to indicate choice of encryption algorithems. Both the Caller and Callee roles use the same set of algorithms although they are shown only in the caller side. Consequences The advantages of this pattern include: Symmetric encryption approaches provide good confidentiality. Encryption is performed transparently to the users activities. The need to provide separate VLANs for VoIP security could possibly be removed. It may no longer be necessary to use IPSec tunneling that was previously required in the MAN/WAN. Figure 4 Class Diagram for a VoIP Secure Channel Possible disadvantages include: The quality of the call can be affected if encryption is not performed very carefully [Wal05]. It is hard to scale because of the need for shared keys.

Post Traumatic Stress Disorder ( Ptsd ) - 783 Words

Freedom bears a heavy price. Many soldiers pay with their lives, while others relive the sights, sounds, and terror of combat. Post-Traumatic Stress Disorder (PTSD) affects thousands of American veterans and their families each year. Is PTSD simply a weakness, or is it an epidemic? Though historically, the validity of PTSD was argued, the pain is real, and there is a diagnosis to prove it. Combat-related PTSD stems from witnessing the suffering and death of others, and the exposure of destruction, personal danger, and injury. A heightened risk may also result from a soldier’s specific role in the war. One study of Vietnam soldiers provides insight on potential risk factors and reveals an unexpected contributor to the development of PTSD. This study suggests that those who suffered the worst cases of PTSD had sustained stressful and traumatic childhood abuse. The study examined two groups of Vietnam soldiers in an attempt to determine a predisposition for PTSD. 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Atomic Bomb Essay Thesis Example For Students

Atomic Bomb Essay Thesis Just before the beginning of World War II, Albert Einstein wrote a letter to President Franklin D. Roosevelt. Urged by Hungarian-born physicists Leo Szilard, Eugene Wingner, and Edward Teller, Einstein told Roosevelt about Nazi German efforts to purify Uranium-235 which might be used to build an atomic bomb. Shortly after that the United States Government began work on the Manhattan Project. The Manhattan Project was the code name for the United States effort to develop the atomic bomb before the Germans did. The first successful experiments in splitting a uranium atom had been carried out in the autumn of 1938 at the Kaiser Wilhelm Institute in Berlin(Groueff 9) just after Einstein wrote his letter. So the race was on. Major General Wilhelm D. Styer called the Manhattan Project the most important job in the war . . . an all-out effort to build an atomic bomb.(Groueff 5) It turned out to be the biggest development in warfare and sciences biggest development this century. The most complicated issue to be addressed by the scientists working on the Manhattan Project was the production of ample amounts of enriched uranium to sustain a chain reaction.(Outlaw 2) At the time, Uranium-235 was hard to extract. Of the Uranium ore mined, only about 1/500 th of it ended up as Uranium metal. Of the Uranium metal, the fissionable isotope of Uranium (Uranium- 235) is relatively rare, occurring in Uranium at a ratio of 1 to 139. (Szasz 15) Separating the one part Uranium-235 from the 139 parts Uranium-238 proved to be a challenge. No ordinary chemical extraction could separate the two isotopes. Only mechanical methods could effectively separate U-235 from U-238.(2) Scientists at Columbia University solved this difficult problem. A massive enrichment laboratory/plant(Outlaw 2) was built at Oak Ridge, Tennessee. H. C. Urey, his associates, and colleagues at Columbia University designed a system that worked on the principle of gaseous diffusion. (2) After this process was completed, Ernest O. Lawrence (inventor of the Cyclotron) at the University of California in Berkeley implemented a process involving magnetic separation of the two isotopes.(2) Finally, a gas centrifuge was used to further separate the Uranium-235 from the Uranium-238. The Uranium-238 is forced to the bottom because it had more mass than the Uranium-235. In this manner uranium-235 was enriched from its normal 0.7% to weapons grade of more than 90%.(Grolier 5) This Uranium was then transported to the Los Alamos, N. Mex. , laboratory headed by J. Robert Oppenheimer.(Grolier 5) Oppenheimer was the major force behind the Manhattan Project. He literally ran the show and saw to it that all of the great minds working on this project made their brainstorms work. He oversaw the entire project from its conception to its completion.(Outlaw 3) Once the purified Uranium reached New Mexico, it was made into the components of a gun-type atomic weapon. Two pieces of U-235, individually not large enough to sustain a chain reaction, were brought together rapidly in a gun barrel to form a supercritical mass that exploded instantaneously.(Grolier 5) It was originally nicknamed Thin Man'(after Roosevelt, but later renamed Little Boy (for nobody) when technical changes shortened the proposed gun barrel. (Szasz 25) The scientists were so confident that the gun-type atomic bomb would work no test was conducted, and it was first employed in military action over Hiroshima, Japan, on Aug. 6, 1945.(Grolier 5) Before the Uranium-235 Little Boy bomb had been developed to the point of seeming assured of success,(Grolier 5) another bomb was proposed. The Uranium-238 that had been earlier ruled out as an option was being looked at. It could capture a free neutron without fissioning and become Uranium-239. But the Uranium-239 thus produced is unstable (radioactive) and decays first to neptunium-239 and then to plutonium-239.(Grolier 5) This proved to be useful because the newly created plutonium-239 is fissionable and it can be separated from uranium by chemical techniques,(6) which would be far simpler than the physical processes to separate the Uranium-235 from the Uranium-238. Once again the University of Chicago, under Enrico Fermis direction built the first reactor. The Scarlet Letter Persuasive Essay Their mission had been successfully accomplished, however, they questioned whether the equilibrium in nature had been upset as if humankind had become a threat to the world it inhabited.(Outlaw 3) Oppenheimer was ecstatic about the success of the bomb, but quoted a fragment from Bhagavad Gita. I am become Death, the destroyer of worlds. Many people who were involved in the creation of the atomic bomb signed petitions against dropping the bomb. The atomic bomb has been used twice in warfare. The Uranium bomb nicknamed Little Boy, which weighed over 4.5 tons, was dropped over Hiroshima on August 6, 1945. At 0815 hours the bomb was dropped from the Enola Gay. It missed Ground Zero at 1,980 feet by only 600 feet. At 0816 hours, in the flash of an instant, 66,000 people were killed and 69,000 people were injured by a 10 kiloton atomic explosion.(Outlaw 4) See blast ranges diagram Nagasaki fell to the same treatment as Hiroshima on August 9, 1945. The plutonium bomb, Fat Man, was dropped on the city. It missed its intended target by over one and a half miles. Nagasakis population dropped in one split-second from 422,000 to 383,000. 39,000 were killed, over 25,000 were injured. That blast was less than 10 kilotons as well. Physicists who have studied the atomic explosions conclude that the bombs utilized only 0.1% of their respective explosive capabilities.(Outlaw 4) Controversy still exists about dropping the two atomic bombs on Japan. Arguments defending the Japanese claim the atomic bomb did not win the war in the Pacific; at best, it hastened Japanese acceptance of a defeat that was viewed as inevitable. (Grolier 8) Other arguments state that the United States should have warned the Japanese, or that we should have invited them to a public demonstration. In retrospect that U.S. use of the atomic bomb may have been the first act of the cold war.(Grolier 8) On the other side, advocates claimed that the invasion of the Japanese islands could and would result in over one million military casualties plus the civilian losses based on previous invasions of Japanese occupied islands