Take a peek at the locking process below: Once an item is unlocked, only things with greater numbers may be locked. Any time may be used to open a lock. The X-lock is the sole kind of lock used. Give an example of how the protocol does not ensure serializability.

Take a peek at the locking process below: Once an item is unlocked, only things with greater numbers may be locked. Any time may be used to open a lock. The X-lock is the sole kind of lock used. Give an example of how the protocol does not ensure serializability.

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

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RSA cryptosystem Let p = 29 and q = 31. Then the RSA modulus n = pq = 899. We set the length of plaintext blocks to be 2 and the length of ciphertext blocks 3. Let the encryption exponent b = 29. If, for example, we want to encrypt the word live, we first divide the word into blocks of length 2, li and ve, and then find its corresponding number blocks 11 8 and 21 4. We consider these number blocks as numbers in base 26. Then we find the corresponding integers in base 10, that is 11 8 = 11 × 26 + 8 = 294 and 21 4 = 21 × 26 + 4 = 550. The integers 294 and 550 are regarded as modular numbers in Z899 and encrypted as 29429 (mod 899) = 91 and 5502⁹ (mod 899) = 492. Now write 91 and 492 in base 26 of length 3 we get 91 = 0 x 26² +3 x 26 +13 and 492 = 0 x 262 +18 × 26 +24 and the corresponding number blocks of length 3 are 0 3 13 and 0 18 24. Hen the ciphertext for live is ADNASY as 0 3 13 = ADN and 0 18 24 = ASY.
Bob has sent his secret number m to Alice via secure RSA encryption. Break his ciphertext to find m. To factorize the number N, you can use the program. Alice's public key (e, N) = (17, 29329): Bob's ciphertext c = 16469
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.
Here's how to secure your bike: Only things with a higher number may be locked again after being unlocked. Locks may be unlocked at any moment. All the locks are X-locks. Demonstrate how serializability is not ensured by the protocol.
The locking technique is detailed below. After being unlocked, only things with a higher number may be locked again. Keys may be used at any moment. We only use X-locks. Demonstrate how serializability is not ensured by the protocol.
Now assume that the user used only 34 characters from the keyboard. What is the key length in bits in this case? Provide the correct answer for the fourth question. This is not a graded assignment.
Suppose Alice used a Hash function HA to encrypted her sensitive data. Everyone in the public can access her encrypted data. Group of answer choices She must keep HA secret and should not share it with others. She can share HA with other users. She must keep HA secret but can share it with others after encryption. None of the above.
Is it possible to "decrypt" a hash of a message in order to obtain the original message? Give an explanation for your answer.
Find out what risks are involved with the various authentication techniques and suggest a way to deal with the following situation.Bob uses a cryptographic hash function to check a password against a cache of other hashes.Bob performs a cryptographic hash on a password and checks it against a database of previously double-hashed passwords.
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…
). This problem is about the chaining method we discussed in the class. Problem 3 (, Consider a hash table of size N = 11. Suppose that you insert the following sequence of keys to an initially empty hash table. Show, step by step, the content of the hash table. Sequence of keys to be inserted:
See the procedure for securing below: After unlocking, only higher-numbered items can be sealed. Anytime may be used to unlock locks. Used exclusively are X-locks. Demonstrate how the protocol cannot guarantee serializability.