计算机 网络 外文翻译 外文文献 英文文献 详解加密技术概念、加密方法以及应用.doc

Along with the technical developing of the network,the network safety also becomes the focus in the focus of the network society nowadays,almost no one not at discuss the safe problem of the network,virus, a procedure,mail bomb,the long range interception etc.the all these let persons tremble with fear scared.Virus,black guest of rampant make body for today the people of the networksociety feel talk that thenet colorchange,indecisive. But we are essential to know clearly,the safe problem of all these everything we cant find out the solution once and all,having plenty of besides basically cant find out the exhaustive solution, suchas the virus procedure,because any anti-virus procedure all only the ability then can develop out after mew virus detection,returning to have no currently which ability an anti-virus software develop the software that the company dares to promise them and can check to kill all have already know ofand unknown virus ,so we cant have etc.network safetyagain the mind that get to the Internet,because probably the network cant have so on first,for the elephant"pike"and"shields",the network and virus,black guests are a rightness of coexistence bodies forever. The computer of the modern encrypt technique be adapted the network the demand of the safetybut should carrythe output, it carries on the general electronic commerce activity to provide the safety for us guarantee,such as carry on documents deliver in the network,the E-mail come-and-go and carryon the contracttext originally of sign etc.Encryptthe technique in factalso isnotwhatnew-bornthing,onlyapplied in nowadayselectroniccommerce,thecomputernetwork still thehistory ofthe lastfew years.Underneath wethe detailed introduction encryptthetechnique tostill have superficial knowledge offriend provide opportunities ofdetailed understanding! One,thecause ofencrypt Encryptis a kind of methodthat usedto protect data, it exist fora long time,the history thatis producedisverylongago, it istooriginateandtracebackto in 2000B.C.(afewcentury),although it is not now we speak of encrypt the technique(even not call encrypt),be a kind concept for encrypt,define bore as early as and several centuries ago.At that time theEgyptian usedthe special pictographto bethe information coding firstof,changing along with time,the Babylon,Mesopota-mia was second to start use some method with Greece civilizations all to protect their written forminformation. Encryptthetechniquetomainlybeapplied in themilitaryrealm in thenearfuture,suchasthe American independent war,American civil war and two world wars.The coding machine that behave to know most widely is the machine of German Enigma,the German makes use of in the worldwarII it establishestoencrypttheinformation.Thus,becauseoftheeffortoftheAlanTuring and Ultra plan and others they carries on to breakthe solution to the Germans password finally.At the beginning, the research of the calculator be for breaking the password of the solve the German,the people did not thought of that the calculator give information revolution bring today.Along with the development of the calculator,which build up of the operation ability,past passwords allied become very simple ,hence the people studied constantly again the new data encrypts the way,if make use of the output and private key and male keys of calculate way of ROSAs are outputon this foundation. Two,thereasonwhyweuseencrypt Nowadays the networksociety the choice to encrypt is already essential tous,one weknow is that going forward to communicate officially the piece to deliver in the Internet ,the E-mail business come-and-go exist many in security factors,taking charge of to some archdukes especiallytodeliver withsomesecretdocumentsonthenetwork.Andthiskindofinsecurityis the Internet existence foundation-TCP/IP argument proper,include some according to TCP/IP of service;on the other hand ,the Internet brought infinite business opportunities for numerous companys house,theInternet connectsthe whole world at together,headed forthe Internet tomean toheadfortheworld,this goodmatterthataretolongfor in smallbusinessenterprise.Forsolving this antinomies,for the sake of the ability is in the safety of foundation up greatly open this door that lead tothe world ,wehad to choose thedata to encryptand according toencryptthe technique numeralsignature. Encrypt in the function on the network is to prevent from useful or the privatization information be intercept on the network and steal.A simple example is a password to deliver,the calculator password is extremely important,many safe protection system is according to password of,thepasswordrevealoverallbreakupthatcomesuptospealtomeanitssafesystemin acertain meaning. Whilecarryingonregisterthoughtanetwork,thepasswordkey-inis deliver withtheformof the clear statement server,but network ascend of eavesdrop is an extremely easy affair,so the customerofRoot orcustomeroftheAdministrators,thatresult will beextremely serious. Return the like fruit your company at carry on a certain invitation to bid items bid to work,thestaffmembergivesoutouttheinvitationtobidunittothemarkbookoftheir unit in the wayofE-mail,ifhavethis time,knowingtheobjectthatyourcompanybidfrom it ,thatresultwill how,believe need notsaycleverness moreofyou arealsounderstand. Such example is really too many , the project that solves the above-mentioned hard to crack is to encrypt, encrypt behind of mark book have no private key of consignee and also cant untie ,mark disorderly code that book become a lot of to have no actual meaning .In fine regardless is unit or personal come up to say in a certain meaning that ages that encrypt to also becomethenetworksociety tocarryonthedocumentorthemailSSLsnowadayssymbolize! Numerical signature be according to encrypt the technique ,its function be use whether certain customer is true or not .Apply is still an E-mail at most,such as be customerto receive an E-mail,mail top the mark has the addressees name and the mailbox addresses,the many people maythink in brief theaddresseris alatterupexplanatorythatperson,butforgeanE-mailactually for an usually person to say that is an extremely easy matter .In this kind of case,will use the numeral signature of the encrypt the technique foundation,use it the confirmation sends letter the reliability ofthe Human body. The similar numeral signature is technical to still have an attestation of a kind of body technique ,some stations orderto provide into the station FTPand theWWW service,certainly this servicethatusuallyget in touchwithisananonymousservice,thepowerofthecustomerwantsto be subjected to the restrict ,but this service that also have is not anonymous ,such as the some companyprovidethecustomertocooperatethenotanonymousFTPofcolleague forthesakeof the information exchanges service,or develop the group their web carries the customer up of server of WWW up,the problem of now be ,customer be the customer think of that person,an attestation ofbody thetechnique is a goodsolution. Need to be emphasize here that 1:00be,the document encrypt in fact no t used for E-mail or the document on the networks deliver only,also can apply the document protective of the static statein fact,cancliptocarryonencrypttothedisk,thedocumentprthedocument in theharddrive suchas the software ofPIP,inorderto preventthe others steal amongthem ofinformation. Three,twokinds of encryptmethod The encrypt technique is usually divided into the two major types:"Symmetry type"and"not symmetrytype". The symmetry type encrypt is to encrypt and decrypt to use the same name of key of encrypt,usually call it as"the Session Key"this kind of encrypt the technique currently drive extensive adoption,encrypt such as the DES that American government adopt the standard is a kindof "symmetrytype"of typicalmodeltoencryptthemethod,itsthelengthofSessionKeyis a 56Bites. The not symmetry type encrypt is to and decrypt use of is not the same of key of encrypt,usually havetwoencryptkeys,becalled "male key"and"privatekey",theytwomustform couples the usage,otherwise cant open to encrypt the document."Male key"here means and can announce outward of,"private key" then cant ,only the ability is know by a person of holder.Its superior sex right here,because the symmetry type encrypts the method if deliver to encrypt the document on the network very difficult tell the other party the key of the encrypt,use in spite of what method all was probably do not eavesdrop.Rather than the symmetry type encrypt the methodcontaintwoencryptkeys,and "malekey"inwhichis canpubliclyof,alsoknowforthenot afraid other people,the consignee decrypt as long as use own private key then with,thus nicely avoided thekey ofencryptdeliver the safetyproblem . Four,themanagement ofthe keyof encrypt The key of encrypt requests to keep secret since this involve the key of encrypt of the management problem ,if dont manage well,the key is possible revealed unconsciously,is not to have the key of encrypt, any keep also just opposite ,sometimes effect.To manage the good key ,westill needto notice following few aspect: 1,theusageof thekey wantstonotice the time limited efficacy andnumber oftimeless Ifthe customercan use the same key and other people to exchange the information once and with a run, sokey alsotogether other any passwords are similar to existthe certain safety.although say that the private key of the customer is wrong the outside is is public of,also can hardly guarantee the confidentiality of the private key long-term, the very difficult assurance was not reveal for long time.If someone knew the key of the customer accidentally,so customer ever and each news that another person exchange no longer are to keep secret of.use another information that particular key encrypt more many,provide to eavesdrop of material also more many,come up tospeak froma certain meaning meaning alsomoreinsecurity. Therefore ,emphasize generally only used for a dialogue key an information in or have a conversation once medium, or build up a kind of replace the mechanism of the key to let up the possibility ofthe revelation on time. 2.the management ofencrypt Suppose to have 100 persons in some organization,if they arbitrarily two peoples can carry on the secret dialogue, need so and altogether how many keys?Everybody need know how many keys?Perhaps veryeasy get an answer, if of any twopersonwants thedifferent key,then need 4952 altogether ,andeverybody should remember99 keys.Ifthe number of the organization is 1000 and 10000 people or more , this kind of way obviously and too stupid,the management key will be a terrible affair. The Kerberos provided a kind of solve this better project,it is to be invent by the MIT of,make management of keep secret the key and distribute to become very easy ,but this kind of method still exist the certain weakness.In order to can provide a practical solution on Internet,the Kerberos built up a safety of,the key of the dependability distributes the center(the Key Distribution Center ,KDC),each customer as long as know a different from KDC carry on the key ofthe conversation all rightly,but donotneed to know100 upto thousandthkey. Suppose the customer A wants to carry on the secret correspondence with the customer B,then the customer A first and KDC correspondence,use to only have the customer A and KDCs to know of the key of the carry on encrypt,the customer A tell the KDC that he thinks to carry on thecorrespondencewiththecustomerB,andbornlabel,this labeliscarryonbytheKDCandkey of between the customerB to encrypt,and at the customer A start and the customerB dialogue,the customer A will hand over to the customer B this label.The function of this label is to let the customer A make sure is the customer B with his confabulation, not the one who pretend to be .Because this label is from only the key that the customer B and KDCs know carry on encrypt of,so the one who even pretends to be gets the label customer A send out to also impossibly carry on decrypt,only the customer B can carry on decrypt enough after receive, the person who thus made sure tohave a conversation with the customerA is customerB. When born label and random conversation passwords of KDC,would they use only have the customer A and KDCs know of the carries on encrypt ,then pass the customer A to the label and the conversation key ,theresult forencryptcaninsure to only have the customerA andcan getthis information ,only have the customer A and can make use of this conversation key and the customer B to carry on converse.Manage together ,the KDC will encrypt the key that the conversation password use to have KDC and the customer B to know , and give the customer B the conversation key. The customer A will startan and the conversation of the customer B,counteract to get of the conversation key encryptthe oneself and the body ofthe assurancecustomer B,still wantthe KDC passes it of the label passes the customerB with the body ofthe assurance customerB, then of the customer A and the customer B can use the conversation key carries on the safety of the conversation ,and for the sake of the assurance safety,this conversation key is a time ,the thus blackguestismoredifficulttocarriedontobreaktosolve.Atthesametimebecausethekeyis a sex to be is automatic by the system to produce of ,then the customer need not record so many keys,conversation the peoples correspondence. Five,encryptthetechnicalapplication Theapplicationoftheencrypttechnicalis various,butthemostextensiveis in theelectronic commerceandthe application onthe VPNs,wewill distinguish it simple as follow: 1,theapplication in electronic commerce The electronic commerce(E-business)request the customer and can go forward to go various business activity in the net,need not worry that own credit card would be appropriate by the person.At past,customer for keeping the number fo the credit card from burglarize to take ,order through a telephone generally ,then use the credit card ofthe customer to carry the payment .Now the people start to encrypt the technique with the RSA(a kind of public/ privately owned key),the safety that the exaltation credit card trade.thus make the electronic commerce alignment practical tomake possible. Many persons all know that the company of NETSCAPE leads the technical promoter in the business of Internet,that companyprovided a kind of according to RSAand keep secret the key of application in the technique of Internet,is be called safe electric outlet layer.(The Secure Sockets Layer,SSL)Perhapsthe many people knows the Socket ,it is a plait distanceinterface,dont provide any safe measure ,but the SSLnot only provide to weave the distance interface ,but also heading up to provide a kind of service of safety,the SSL3.0 have already applied to the server and browsersnow up,the SSL2.0thencanbe apply in the servercarry only. Aft