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Recent questions tagged network-security

1 vote
2 answers
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The ability to inject packets into the Internet with a false source address is known as Man-in-the-middle attack IP phishing IP sniffing IP spoofing
asked Jul 2, 2019 in Computer Networks Arjun 416 views
1 vote
1 answer
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The RSA encryption algorithm also works in reverse, that is, you can encrypt a message with the private key and decrypt it using the public key. This property is used in instruction detection systems digital signatures data compression certification
asked Jul 2, 2019 in Computer Networks Arjun 421 views
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1 answer
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A math class has 25 students. Assuming that all of the students were born in the first half of the year—between January 1st and June 30th— what is the probability that at least two students have the same birthday? Assume that nobody was born on leap day, so there are 181 possible birthdays.
asked Mar 19, 2019 in Computer Networks ajaysoni1924 119 views
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33. Two users can establish a shared secret key using the Diffie-Hellman algorithm, even if they have never met, share no secrets, and have no certificates (a) Explain how this algorithm is susceptible to a man-in-the-middle attack. (b) How would this susceptibility change if n or g were secret?
asked Mar 19, 2019 in Computer Networks ajaysoni1924 97 views
0 votes
1 answer
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The Diffie-Hellman key exchange is being used to establish a secret key between Alice and Bob. Alice sends Bob (227, 5, 82). Bob responds with (125). Alice’s secret number, x, is 12, and Bob’s secret number, y, is 3. Show how Alice and Bob compute the secret key.
asked Mar 19, 2019 in Computer Networks ajaysoni1924 247 views
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Alice wants to communicate with Bob, using public-key cryptography. She establishes a connection to someone she hopes is Bob. She asks him for his public key and he sends it to her in plaintext along with an X.509 certificate signed by the root CA. Alice already has the public key ... is talking to Bob? Assume that Bob does not care who he is talking to (e.g., Bob is some kind of public service).
asked Mar 19, 2019 in Computer Networks ajaysoni1924 71 views
0 votes
1 answer
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Alice and Bob use RSA public key encryption in order to communicate between them. Trudy finds out that Alice and Bob shared one of the primes used to determine the number n of their public key pairs. In other words, Trudy found out that na = pa × q and nb = pb × q. How can Trudy use this information to break Alice’s code?
asked Mar 19, 2019 in Computer Networks ajaysoni1924 129 views
1 vote
2 answers
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Using the RSA public key cryptosystem, with a = 1, b = 2 . . . y = 25, z = 26. (a) If p = 5 and q = 13, list five legal values for d. (b) If p = 5, q = 31, and d = 37, find e. (c) Using p = 3, q = 11, and d = 9, find e and encrypt ‘‘hello’’.
asked Mar 19, 2019 in Computer Networks ajaysoni1924 201 views
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I'm not able to distinguish the difference between digital certificate and digital signature Correct me if there is flaw in my understanding : A Digital Certificate is certificate of authenticity and it is given to any host by a trusted third party which leases it ... on the other hand is dished out by the client/server whenever it attempts to make any data transfer and it ensure data integrity
asked Mar 11, 2019 in Computer Networks s_dr_13 56 views
13 votes
6 answers
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In an RSA cryptosystem, the value of the public modulus parameter $n$ is $3007$. If it is also known as that $\phi(n)=2880$ where $\phi()$ denotes Euler’s Totient Function, then the prime factor of $n$ which is greater than $50$ is _________
asked Feb 7, 2019 in Computer Networks Arjun 4.1k views
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It is impossible to produce a document that differs from the original document with single bit change and valid signature I am unable to understand, why is it impossible? bit changing is one way of intruder to steal information.right? plz give some valid reason
asked Dec 31, 2018 in Computer Networks srestha 77 views
3 votes
1 answer
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Which of the following is TRUE with respect to Diffie-Hellman Key exchange algorithm? It can be used for encryption or decryption purpose It doesn't suffer from man in the middle attack It suffers from bucket brigade attack It is an example of private key cryptography algorithm
asked Dec 27, 2018 in Computer Networks Ruturaj Mohanty 471 views
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From a large set of prime numbers Jimmy choose 23 and 17 as P and Q respectively and a random integer to be 13. Jimmy wants to sends a plain text to M = 127. What will be the value of cipher text using RSA? since i am getting ciphertext =(127^13) mod 391 now how should i calculate
asked Dec 17, 2018 in Computer Networks vijju532 138 views
0 votes
2 answers
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Let M be a confidential email that Alice wants to send to Bob, $K_B$ be Bob's encryption public key, and $K_A^{-1}$ be Alice's private key for signing. Which of the following options would be the best choice for protecting confidential emails? ... Encrypted message, Alice should sign the encrypted message and then should send this signature along with the encrypted message to BOB. Please help.
asked Nov 27, 2018 in Computer Networks Ayush Upadhyaya 381 views
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Consider RSA with p = 31 and q = 47. I. n = 1457 II. z= 1200 III. 7 is acceptable choice for e Which of the following is true ? A. Only I B. Only I and II C. Only I and III D. All of I,II and II I am Getting answer (C), but answer is given (D). As per kurose Ross, Z is defined to be $(p-1)(q-1)$
asked Nov 27, 2018 in Computer Networks Ayush Upadhyaya 207 views
0 votes
1 answer
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suppose that a message has been encrypted using DES in chipertext block chaining mode. One bit of chipertext in block Ci is accedntally transformed from 0to 1during transmissin. How much plaintext will be grabled as a result? a)1 b)2 c)n- d)n-i+1
asked Oct 28, 2018 in Computer Networks balaganesh 117 views
0 votes
1 answer
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Using RSA key crypto system with a = 1, b = 2 etc; value for encryption if prime value are p = 7 and q = 11, the legal value for secret key is . a)69 b)49 c)49 d)119
asked Oct 12, 2018 in Computer Networks Shivangi Parashar 2 428 views
0 votes
1 answer
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3 votes
2 answers
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Which of following risk may arise when same key is used to encrypt direction of communication channel,that are not present if we use different key in both directions ? A. Reflection attack B. Denial of Service C. Eavesdropping D. None
asked Sep 15, 2018 in Computer Networks Na462 252 views
1 vote
4 answers
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DH key exchange algorithm is used to establish a session between sender and receiver with n=23 and g=5. The sender's secret key is 6 and the receiver's secret key is 15. What is the secret key between the receiver and sender? Please explain with solution P.S: Answer is given as 2
asked Aug 18, 2018 in Computer Networks Kalpataru Bose 208 views
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Ques. Which of the following is incorrect? A. In circuit switched network, switches require connection establishment and teardown phases, where as in packet switched network doesn't. B. Unlike packet switching, circuit switched networks do not need any ... a destination address. D. Under some circumstance, a circuit switched network may prevent some sender from starting new conversation.
asked Jul 15, 2018 in Computer Networks Brij gopal Dixit 1 106 views
0 votes
2 answers
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Consider the following services in network security: 1. Authentication of message 2. Integrity 3. Privacy 4. Non repudiation Which of the security services is/are not provided by digital signature?
asked Apr 30, 2018 in Computer Networks Kartavya Kothari 270 views
3 votes
3 answers
25
In cryptography, the following uses transposition ciphers and the keyword is LAYER. Encrypt the following message. (Spaces are omitted during encrypton) WELCOME TO NETWORK SECURITY! WMEKREETSILTWETCOOCYONRU! EETSICOOCYWMEKRONRU!LTWET LTWETONRU!WMEKRCOOCYEETSI ONRU!COOCYLTWETEETSIWMEKR
asked Apr 22, 2018 in Computer Networks Arjun 2.8k views
2 votes
1 answer
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Avalanche effect in cryptography Is desirable property of cryptographic algorithm Is undesirable property of cryptographic algorithm Has no effect on encryption algorithm None of the above
asked Apr 22, 2018 in Computer Networks Arjun 1.1k views
1 vote
3 answers
27
What is one advantage of setting up a $DMZ$ (Demilitarized Zone) with two firewalls? You can control where traffic goes in the three networks You can do statefull packet filtering You can do load balancing Improve network performance
asked Apr 22, 2018 in Computer Networks Arjun 1.5k views
1 vote
4 answers
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Which one of the following algorithm is not used in asymmetric key cryptography? RSA Algorithm Gillie-Hellman Algorithm Electronic Code Book Algorithm None of the above
asked Apr 22, 2018 in Computer Networks Arjun 2.3k views
2 votes
3 answers
29
$\textbf{VPN}$ Works at which layer? Application layer Transport layer Network layer Data-link layer
asked Apr 5, 2018 in Computer Networks hacker16 671 views
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