Consider a simple authentication protocol below. A simple authentication protocol (1) C➜ AS: III || PI || III (2) AS C: TTTTTT (3) CV: III || TTTTTT TTTTTT= E(KI, [III || PI ||III]) where C = client, AS = authentication server, V = server, IDC - identifier of user on C, IDV = identifier of V, PC = password of user on C, KV = secret encryption key shared by AS and V 1. 11. What are the two main problems in this simple protocol? Suggest possible improvements to the protocol to address the problems.

Consider a simple authentication protocol below. A simple authentication protocol (1) C➜ AS: III || PI || III (2) AS C: TTTTTT (3) CV: III || TTTTTT TTTTTT= E(KI, [III || PI ||III]) where C = client, AS = authentication server, V = server, IDC - identifier of user on C, IDV = identifier of V, PC = password of user on C, KV = secret encryption key shared by AS and V 1. 11. What are the two main problems in this simple protocol? Suggest possible improvements to the protocol to address the problems.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

See similar textbooks

Similar questions

A cipher suite is a choice of algorithms for key exchange, authentication and encryption to be used together in TLS. Cipher suites are specified by an abbreviation such as the following: “ADH-DES-CBC-SHA”. Search online and find one example of a cipher suite used in TLS 1.3. Write the name of the cipher suite; then, for each component, write what the abbreviation stands for and for which cryptographic task that algorithm is used in that suite.
One of the problems with the Internet email system is that sending forged emails is relatively straightforward, i.e., it is easy to send an email with a fake sender/from address. One solution to this problem would be for a domain’s mail servers to digitally sign any email originating from the domain. For this to be useful, the public key would need to be made available to clients to validate the signatures. It is proposed that the public keys of the mail servers will be verified and signed by a certification authority (same as SSL/TLS certificates) and distributed via a standardised URL for the domain, e.g., https://mybusiness.com/email.pubkey. (a) Explain how the client would obtain the public key and validate the email server’s digital signatures. (b) Discuss the problem of trusting the obtained public key and how this solution results in public keys that can/cannot be trusted. (c) Indicate whether you believe this approach could be used to prevent forged emails and explain why it…
2. Recall the concept of Physically Unclonable Functions, which are an importantcomponent of hardware based security. Here is a simple scenario and simple protocol usingPUFs for authenticating a tag. In the protocol below, the Reader stores ALL possiblecombinations of Challenge-Response pairs for every tag it needs to authenticate. Duringauthentication, the Reader broadcasts the ID of the tag, and a greeting (Gn ). Every tag maysee this message, but only the one with the right ID will process the message. The right tagwith the ID in the message will then feed the greeting to its PUF and compute the responseSn. The response is then sent to the Reader. This should be clear from the Figure below. Forthe next round of authenticating the same Tag, the process repeats with a new Greeting(G n+1 ). Since the Reader has the responses, authentication is straightforward. Recall thatChallenges and Responses are typically 128 or 256 bit strings for RFIDs.From the protocol, and class, it should be…
Public Key Authority is one such instance. The Public Key Authority must prepare a request for B's public key before delivering a message to A (E(PRauth[PUB || Request || Time 1]). It is debated if the letter A should be used to decipher the message.
For the Zhou-Gollman non-repudiation protocol discussed in the lecture on “Non-Repudiationand Anonymity Protocols”, which one of the following statements is false:
Exercise 2 ( In module 4 we discussed many examples of security protocols using formal notation. For instance, we studied how a dual-factor authentication works when a password generator is used: S → U : N U → P : N, PIN P → U : {N,PIN}K U → S: {N,PIN}K Can you modify the set of rules outlined above to describe the protocol of dual-factor authentication when a mobile device is involved? To receive full credit, please submit 1. a high-level overview of how the protocol would work (e.g. the mobile phone might provide a PIN to the user as opposed to just "clicking" on a button directly on the phone) 2. the description of the protocol using the formal notation
Bob has designed a secure login system for the student portal of the Xiamen University of Technology (XUT). In Bob's design, a two-factor authentication method is used for verifying the authenticity of the user. A brief description of the design is provided below. For the two-factor authentication, the followings are required: • Factor 1: a user first required to provide a secret password, • Factor 2: the user then needs to provide the correct answer to a security question. To securely store the user password in the system, Bob has used state-of-the-art encryption algorithm, Advanced Encryption Standard (AES), to encrypt the user password and stored the encrypted password in the system database. For securely signing in to the system: the user needs to provide his/her user ID and the corresponding password. This information will be transmitted to the system over a secure communication channel. Upon receiving this information, the system will: o locate/retrieve the corresponding…
Suppose an attacker wants to break a cryptographic scheme - (Gen, Enc, Dec). The attacker kows that for some message m and ciphertext c, it is true that Pr [C=c | M=m] << Pr [C = c). !3! The attacker listens to the channel and sees the ciphertext c. What conclusion can the attacker draw? Note that << means "much less" The scheme has no bias. O The message is probably m. OThe distribution of the messages over the message space is not uniform. The message is probably not m.
Public Key Authority is one such instance. The Public Key Authority must prepare a request for B's public key before delivering a message to A (E(PRauth[PUB || Request || Time1]). It is debated if the letter A should be used to decipher the message.
Consider the following simple authentication dialogue: C → AS: IDc II Pc II IDv AS → C: Ticket C → V: IDc II Ticket; Ticket = E(Kv, [IDc II ADc II IDv]) Where: C = client AS = authentication server V = server IDc = identifier of user on C IDv = identifier of V Pc = password of user on C ADc = network address of C Kv = secret encryption key shared by AS and V ***Explain the process of this protocol.
8 Consider the following protocol: A→ KDC: KDC → A: A → B: B → A: A → B: a. Explain the protocol. b. Can you think of a possible attack on this protocol? Explain how it can be done. c. Mention a possible technique to get around the attack-not a detailed mechanism, just the basics of the idea. IDA IDB NI E(K₁ [KSIDBN₁E(Kb [KSIDA])) E(Kb. [KSIDA]) E(KS, N₂) E(K5, f(N₂))
Suppose that you receive a digital certificate that contains M and (h(M)]CA, where M = (Alice, Alice's public key) and "CA" is Certificate Authority. Assuming that you trust the CA, after verifying the signature on the certificate, what do you then know about the identity of the sender of the certificate? Remember that: [Xleob indicates encryption via Bob's private key to X (signature) h(X) indicates the cryptographic hash function applied to X O The sender is Alice O The sender is Trudy I cannot deduce the identity of the sender from the certificate The sender is the Certificate Authority