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Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 3814.1Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Chapter 14Entity Authentication14.2Objectives To distinguish between message authentication and entity authentication To define witnesses used for identification To discuss some methods of entity authentication using a password To introduce some challenge-response protocols for entity authentication To introduce some zero-knowledge protocols for entity authentication To define biometrics and distinguish between physiological and behavioral techniquesChapter 1414.314-1 INTRODUCTION14-1 INTRODUCTIONEntity authentication is a technique designed to let one Entity authentication is a technique designed to let one party prove the identity of another party. An entity can party prove the identity of another party. An entity can be a person, a process, a client, or a server. The entity be a person, a process, a client, or a server. The entity whose identity needs to be proved is called the whose identity needs to be proved is called the claimant; the party that tries to prove the identity of claimant; the party that tries to prove the identity of the claimant is called the verifier. the claimant is called the verifier. 14.1.1 Data-Origin Versus Entity Authentication14.1.2 Verification Categories14.1.3 Entity Authentication and Key ManagementTopics discussed in this section:Topics discussed in this section:14.4There are two differences between message authentication (data-origin authentication), discussed in Chapter 13, and entity authentication, discussed in this chapter.14.1.1 Data-Origin Versus Entity Authentication1) Message authentication might not happen in real time; entity authentication does.2) Message authentication simply authenticates one message; the process needs to be repeated for each new message. Entity authentication authenticates the claimant for the entire duration of a session.14.514.1.2 Verification CategoriesSomething knownSomething possessedSomething inherent14.6This chapter discusses entity authentication. The next chapter discusses key managment. 14.1.3 Entity Authentication and Key Management14.714-2 PASSWORDS14-2 PASSWORDSThe simplest and oldest method of entity The simplest and oldest method of entity authentication is the password-based authentication, authentication is the password-based authentication, where the password is something that the claimant where the password is something that the claimant knows. knows. 14.2.1 Fixed Password14.2.2 One-Time PasswordTopics discussed in this section:Topics discussed in this section:14.814.2.1 Fixed PasswordFirst Approach Figure 14.1 User ID and password file14.9Second Approach14.2.1 ContinuedFigure 14.2 Hashing the password14.10Third Approach14.2.1 ContinuedFigure 14.3 Salting the password14.11Fourth ApproachIn the fourth approach, two identification techniques are combined. A good example of this type of authentication is the use of an ATM card with a PIN (personal identification number). 14.2.1 Continued14.1214.2.2 One-Time PasswordFirst ApproachIn the first approach, the user and the system agree upon a list of passwords. Second ApproachIn the second approach, the user and the system agree to sequentially update the password. Third ApproachIn the third approach, the user and the system create a sequentially updated password using a hash function.14.1314.2.2 ContinuedFigure 14.4 Lamport one-time password14.1414-3 CHALLENGE-RESPONSE14-3 CHALLENGE-RESPONSEIn password authentication, the claimant proves her In password authentication, the claimant proves her identity by demonstrating that she knows a secret, the identity by demonstrating that she knows a secret, the password. In challenge-response authentication, the password. In challenge-response authentication, the claimant proves that she knows a secret without claimant proves that she knows a secret without sending it. sending it. 14.3.1 Using a Symmetric-Key Cipher14.3.2 Using Keyed-Hash Functions14.3.3 Using an Asymmetric-Key Cipher14.3.4 Using Digital SignatureTopics discussed in this section:Topics discussed in this section:14.1514-3 Continue14-3 ContinueIn challenge-response authentication, the claimant proves that she knows a secret without sending it to the verifier.NoteThe challenge is a time-varying value sent by the verifier; the response is the resultof a function applied on the challenge.Note14.1614.3.1 Using a Symmetric-Key CipherFirst ApproachFigure 14.5 Nonce challenge14.17Second Approach14.3.1 ContinuedFigure 14.6 Timestamp challenge14.18Third Approach.14.3.1 ContinuedFigure 14.7 Bidirectional authentication14.19Instead of using encryption/decryption for entity authentication, we can also use a keyed-hash function (MAC). 14.3.2 Using Keyed-Hash FunctionsFigure 14.8 Keyed-hash function14.2014.3.3 Using an Asymmetric-Key CipherFirst ApproachFigure 14.9 Unidirectional, asymmetric-key authentication14.21Second Approach14.3.3 ContinuedFigure 14.10 Bidirectional, asymmetric-key14.2214.3.4 Using Digital SignatureFirst ApproachFigure 14.11 Digital signature, unidirectional14.23Second Approach14.3.4 ContinuedFigure 14.12 Digital signature, bidirectional authentication14.2414-4 ZERO-KNOWLEDGE14-4 ZERO-KNOWLEDGEIn zero-knowledge authentication, the claimant does In zero-knowledge authentication, the claimant does not reveal anything that might endanger the not reveal anything that might endanger the confidentiality of the secret. The claimant proves to the confidentiality of the secret. The claimant proves to the verifier that she knows a secret, without revealing it. verifier that she knows a secret, without revealing it. The interactions are so designed that they cannot lead The interactions are so designed that they cannot lead to revealing or guessing the secret.to revealing or guessing the secret.14.4.1 Fiat-Shamir Protocol14.4.2 Feige-Fiat-Shamir


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UND CSCI 389 - Entity Authentication

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