A symmetric block encryption algorithm is shown below.16-bit blocks of plaintext P are encrypted using a 32-bitkey. Encryption is defined as:C = (P EX_OR Ko) + K1C is the ciphertext, K is the secret key, Ko is the leftmost16 bits of K, K1 is the rightmost 16 bits of K, EX_OR isbitwise exclusive OR, and + is binary addition.a. The ciphertext C must be the same size as theplaintext P, that is, it must not be larger than 16 bits.How can this be achieved?b. Show the decryption equation. How will theencrypted message be decrypted?

a. The ciphertext C must be the same size as the plaintext P,that is ,it must not be larger than 16…

Answered: A symmetric block encryption algorithm…

Computer Networking: A Top-Down Approach (7th Edition)

7th Edition

ISBN:9780133594140

Author:James Kurose, Keith Ross

Publisher:James Kurose, Keith Ross

Chapter1: Computer Networks And The Internet

Section: Chapter Questions

Problem R1RQ: What is the difference between a host and an end system? List several different types of end...

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Public key cryptosystems are: (more than one may be true, choose all that are true) a offering a simpler way for key distribution B faster than symmetric C the preferred solution when the message we want to encrypt is very large D easily used to offer integrity E requiring advanced hardware in order to use them F easily used to offer confidentiality G marketed better than symmetric that is why people prefer them H using one key for encryption and a different key for decryption
Alice wishes to tell Bob about the animal she saw at the zoo Alice and Bob share the key stream 1101 1001 0000 1010 1110 1101 Alice creates a 3-character ASCII message, encodes it, and sends it to Bob. This is the ciphertext: 1001 1111 0100 0101 1011 0101 Bob deciphers the message. What animal did Alice see at the zoo?
In the case of Public Key Authority It is necessary to make a request for B's public key, and the Public Key Authority must prepare a message (E(PRauth[PUB] || Request || Time1]) before sending it to A. What key A should use to decipher the message is up for debate.
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.
Cryptography problem mathematics Suppose Alice and Bob are using a cryptosystem with a 128-bit key, so there are 2128possible keys. Eve is trying a brute-force attack on the system.(a) Suppose it takes 1 day for Eve to try 264 possible keys. At this rate, how long willit take for Eve to try all 2128 keys? (b) Suppose Alice waits 10 years and then buys a computer that is 100 times fasterthan the one she now owns. Will she finish trying all 2128 keys before or after whatshe does in part (a)?
Use symmetric ciphers to encrypt message "“promise" and decrypt message "FOG". The representation of characters in modulo 26 is described as follows: Plaintext - a bcdefg|hijk1 mnopar stuvwx y z Ciphertext A BCD|EFG|HIJKL|M|NO|P|Q|R s T|U|VwxY|Z Value 00 01 02|03 04 05 06|07|08|09|10|11 12|13|14|15 16|17 18|19 20 21 22 23 24 25 The mathematical equations for encryption and decryption can be described as follows: Encryption Ea:i→i+kmod 26 Decryption Da : i→i-k mod 26 i represents the messages (plaintext or cipher), k represents a symmetric key. In this case k=20
Cypher block chaining and cypher feedback mode may be compared with regards to the number of encryption operations needed to transmit a large file.How much more efficient is one option than the other?
Suppose Data Encryption Standard (DES) is used to encrypt the following 64-bit block of plaintext: 6 3 F A C 0 D 0 3 4 D 9 F 7 9 3 Given the initial 64-bit key is: 1 C 5 8 7 F 1 C 1 3 9 2 4 F E F Expand R0 to get E[R0]
Explain what the following lines of code do pad = len(byteblock)%16 * (-1)byteblock_trimmed = byteblock[64:pad]ciphertext = cipher.encrypt(byteblock_trimmed)ciphertext = byteblock[0:64] + ciphertext + byteblock[pad:]
Perform encryption and decryption using the RSA algorithm for the following: a) p=19; q=23; M = 2; b) p=7; q=31; M = 3;
(c) The following table provides all possible block pairs of plaintext/ciphertext when using some block cipher E with a particular key K. Plaintext Ciphertext Plaintext 0000 1100 1000 1111 1001 0111 1010 1110 1011 1001 0010 1101 0001 0010 0011 0100 0101 0110 0111 1011 1100 1101 1110 1111 Ciphertext 0001 0000 0101 0100 0011 1000 0110 1010 Given that a plaintext P was encrypted using this block cipher operating in a counter mode starting with the counter value of 0, i.e. 0, 1, 2, ..., decrypt the ciphertext C = 010001110111.
Encrypt the first 4 letters of your last name as a block of data to be encrypted. (Let A=1, B=2, C=3,...Z=26). Decrypt the encrypted number to demonstrate that your system works. lastname is john

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