Concept explainers
Suppose you have intercepted a ciphertext message and when you determine the frequencies of letters in this message, you find the frequencies are similar to the frequency of letters in English text. Which type of cipher do you suspect was used?
The Vigenère cipher is a block cipher, with a key that is a string of letters with numerical equivalents
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Discrete Mathematics and Its Applications ( 8th International Edition ) ISBN:9781260091991
- Suppose the alphabet consists of a through z, in natural order, followed by a blank and then the digits 0 through 9, in natural order. Associate these "letters" with the numbers 0,1,2,...,36, respectively, thus forming a 37-letter alphabet, D. Use the affine cipher to decipher the message X01916R916546M9CN1L6B1LL6X0RZ6UII if you know that the plaintext message begins with "t" followed by "h". Write out the affine mapping f and its inverse.arrow_forwardUse the alphabet C from the preceding problem and the affine cipher with key a=11andb=7 to decipher the message RRROAWFPHPWSUHIFOAQXZC:Q.ZIFLW/O:NXM and state the inverse mapping that deciphers this ciphertext. Exercise 7: Suppose the alphabet consists of a through z, in natural order, followed by a colon, a period, and then a forward slash. Associate these "letters" with the numbers 0,1,2,...,28, respectively, thus forming a 29-letter alphabet, C. Use the affine cipher with key a=3andb=22 to decipher the message OVVJNTTBBBQ/FDLWLFQ/GATYST and state the inverse mapping that deciphers this ciphertext.arrow_forwardSuppose that in an RSA Public Key Cryptosystem, the public key is. Encrypt the message "pay me later” using two-digit blocks and the -letter alphabet from Example 2. What is the secret key? Example 2 Translation Cipher Associate the letters of the "alphabet" with the integers. Let and define the mapping by where is the key, the number of positions from the plaintext to the ciphertext. If our alphabet consists of through, in natural order, followed by a blank, then we have "letters" that we associate with the integers as follows:arrow_forward
- Suppose the RSA system that is used for sending secret messages has private key (15, 3) and the cipher text "4" is received. What was the plain text sent? 12 0 8 6 4arrow_forwardEncrypt the word "WATER" by using the cipher function f(p) = (3p+7)mod 26.arrow_forwardThe following parameters are chosen to generate the public and private keys for the RSA cryptosystem. p = 13q = 11e = 37d = 13 If the ciphertext is c = 8, then what is the plaintext m?arrow_forward
- Use the RSA cipher with public key (n, e) = (713, 43) to encrypt the word "TEE." Start by encoding the letters of the word "TEE" into their numeric equivalents. Assume the letters of the alphabet are encoded as follows: A = 01, 8 = 02, C = 03, ..., Z = 26. Since the code for T is 20 and since e = 43 = 32 + 8 + 2 + 1, the first letter of the encrypted message is found by computing 2043 mod 713. 20¹a (mod 713) 20² Eb (mod 713) 204 c (mod 713) 208 d (mod 713) 2032 = f (mod 713) 2016 e (mod 713) b = The result is that a = C = d = e = and f = Thus, 2043 mod 713 = (a · b. d. f) mod 713 = So the first number in the encrypted message is Repeat these computations for each letter to find the complete encrypted message and enter your answer below. (Enter the message as a sequence of integer triples separated by a single space, where each triple is written using a fixed number of digits: 001 for 1, 002 for 2, ..., 099 for 99.)arrow_forwardSuppose (n, d) = (55, 3) is the private key of an RSA cryptosystem. If the received ciphertext is C = 49 what is the corresponding plaintext? O 3 4 10 14arrow_forwardSuppose the Caesar cipher is used to encrypt the message "QUICK." Which of the following cipher text corresponds to this plain text? O TXLFN TLXFN TXLNF None of the Abovearrow_forward
- Decrypt the message "XMJQYJWNSUQFHJ" which was encrypted with a Caesar cipher with a shift of 5 (A to F). Give your response in all caps with no spaces.arrow_forwardHaving chosen primes p and q, and suitable integers d and e, what is the public-key of our RSA cipher in this case? Select one: a. (φ(pq), e) b. (pq, e) c. (d. e) d. (p. q) Clear my choicearrow_forwardProblem 6. In class, we learned a simple symmetric shift cipher (a.k.a. Caesar cipher). The secret key K is an integer in {0, 1,..., 25}. As always, we map each alphabet letter .,Z} to an integer {0, 1,...,25}. The encryption and description are defined x = {A, B, by ... Enc(x, k) = (x + k) mod 26, Dec(x, k) = (x - k) mod 26. (a) As a warm-up, encrypt "CSCI IS COOL" using a Caesar cipher with k='F'. (b) Here's the ciphertext generated by the shift cipher. Find the corresponding plaintext (please explain the approach/strategy you used to find the key). IWXHFJTHIXDCXHTPHNarrow_forward
- Elements Of Modern AlgebraAlgebraISBN:9781285463230Author:Gilbert, Linda, JimmiePublisher:Cengage Learning,