《科技英语文献阅读与翻译》Unit-1-TextB.pptx

*,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,書式設定,書式設定,第 2,第 3,第 4,第 5,*,*,*,Unit One,Text B Digital Signature in Applied Cryptography,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,Unit One,Text B,Digital Signature in Applied Cryptography,7/7/2025,1,第1页,Background Information,7/7/2025,2,Unit One,第2页,cryptography,Cryptography is the study of mathematical techniques related to aspects of information security such as confidentiality,data integrity,entity authentication,and data origin authentication.,As the Internet and other forms of electronic communication become more prevalent,electronic security is also becoming increasingly important.Cryptography is used to protect e-mail messages,credit card information,and corporate data.,7/7/2025,3,Unit One,第3页,public key,It is the key for use with public key encryption methods that is publicly made available.It is published by the key holder or the issuing certification authority.The certification authoritys directory server can distribute it by disk,web download or e-mail.,The public key can be certified using an electronic certificate issued and signed by a certification authority.,7/7/2025,4,Unit One,第4页,private key,It is the key for use with asymmetric encryption that is accessible to the key holder only.Asymmetric encryption uses different keys for encryption and decryption.Each participant is assigned a pair of keys,consisting of an encryption key and a corresponding decryption key.,A private key is used for generating digital signatures and for decrypting data.,7/7/2025,5,Unit One,第5页,hash function and hash value,Hash Function is an algorithm that transforms a string of characters into a usually shorter value of a fixed length or a key that represents the original value.This is called the hash value.,Hash functions are employed in symmetric and asymmetric encryption systems and are used to calculate a fingerprint/imprint of a message or document.,7/7/2025,6,Unit One,第6页,hash function and hash value,When hashing a message,the message is converted into a short bit string-a hash value-and it is impossible to re-establish the original message from the hash value.,A hash value is unique in the sense that two messages cannot result in the same bit string,and any attempt to make changes to the message will negate the value and thus the signature.,7/7/2025,7,Unit One,第7页,digital cash,Digital cash is a digitally signed payment message that serves as a medium of exchange.Digital cash is a system of purchasing cash credits in relatively small amounts,storing the credits in your computer,and then spending them when making electronic purchases over the Internet.,Theoretically,digital cash could be spent in very small increments,such as tenths of a cent(U.S.)or less.Most merchants accept digital cash so far,however,they also use it as an alternative to other forms of payment for somewhat higher price purchases.,7/7/2025,8,Unit One,第8页,source code,Source code is any series of statements written in some human-readable computer programming language.In modern programming languages,the source code which constitutes a program is usually in several text files,but the same source code may be printed in a book or recorded on tape(usually without a file system).,The term is typically used in the context of a particular piece of computer software.,7/7/2025,9,Unit One,第9页,Language Points,7/7/2025,10,Unit One,第10页,This means that an,eavesdropper,refers to Eve,will not be able to listen in on their communication.(para.1):,eavesdropper,n,.a person who listens secretly to private conversation,Nowadays many eavesdroppers are able to connect to your personal computer and phone networks.,eavesdrop,v,.listen secretly to private conversation of others,A new law has been approved by the congress to allow to eavesdrop on private phone conversations.,7/7/2025,11,Unit One,第11页,Digital signatures are,coupled,to the electronic document to which they apply.(para.2):,v.,1)to link or associate together,connect,eg:Pressure,coupled with nervousness made it hard for the president candidate to fall asleep.,2)to join as spouses,marry,eg:Falling in love at the first sight,they coupled as a perfect match.,7/7/2025,12,Unit One,第12页,In public key cryptography,anything Alice encrypts with Bobs public key can be decrypted by Bob with the corresponding private key.(para.3):,In public key cryptography,anything Alice encodes with Bobs public key can be decoded by Bob with the matching private key.,译文:在公钥密码系统里,艾丽斯用鲍勃公钥加密任何内容都能够被鲍勃用对应私钥解密.,7/7/2025,13,Unit One,第13页,Encrypting with a private key thus can be regarded as an,equivalent,to placing ones signature on the message.(para.4):,equivalent,adj,.(to)be equal in value,amount,meaning,n,.something that is equal in value,amount,meaning,eg:Is there a French word that is the exact equivalent of the English word,church,?,7/7/2025,14,Unit One,第14页,A cryptographic hash function can,transform,input of an arbitrary length(para.7):,transform,v.,change completely in form,appearance,or nature,eg:Fatherhood transformed him into a more responsible man.,A steam engine transforms heat into power.,transformation,n,.,eg:Local people have mixed feelings about the planned transformation,of their town into a regional capital.,7/7/2025,15,Unit One,第15页,After all,the second property of the hash function says that the chance that(para.11):,chance,n,.possibility;likelihood,eg:What are her chances of survival?,His quitting has improved my chances of promotion.,(The)chances are(that):It is likely that,eg:Chances are theyll be intent on leaving for Europe.,7/7/2025,16,Unit One,第16页,Using this public key the browser can determine thatthe certificate is,authentic,.(para.18):,authentic,adj,.genuine,of legitimate or undisputed origin;trustworthy,eg:The specialist confirmed that this is an authentic piece of painting by Picasso.,7/7/2025,17,Unit One,第17页,The manufacturer of course promises that the application will not do anything,malicious,.(para.24):,The producer certainly promises that the application will not do anything mean or harmful.,译文:软件生产商当然会承诺使用他们软件不会对用户产生任何不良后果.,malicious,adj,.ill-willed,desiring to harm others,eg:Dont believe the malicious gossip.,malice,n,.,eg:The refugees bear malice towards none.,7/7/2025,18,Unit One,第18页,The CPU in a PC would check the digital signature on the operating system or on applications to be executed.If the digital signature does not check out,or it was not created by an authorized manufacturer,the CPU refuses to execute the operating system or program.(para.28),译文:电脑中央处理器会检验操作系统或要执行应用程序数字署名,假如数字署名有问题,或者不是来自授权生产商话,中央处理器就会拒绝执行操作系统或程序.,7/7/2025,19,Unit One,第19页,