encrypt the message NEED HELP by translating the letters into numbers, applying the encryption function f(p)=(p+3) mod 26, and then translating the numbers back into letters

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.

The following figure is the Cipher Block Chaining (CBC) mode to encrypt large messages. Which of the followings statement is *correct* regarding this mode? IV m₁ m₂ m3 C3 m4 C4 m5 C5 If a message contains two identical 64-bit blocks, the corresponding ciphertext blocks are also identical. Switching the order of two cipher blocks will not cause any detectable error in the plaintext. Duplicating a cipher block will not cause any detectable error in the plaintext. Deleting a cipher block will cause some detectable error in the plaintext. m6 E encrypt with secret key C6

Suppose you intercepted the following encrypted message: 20 5 21 3 49 4 49 3 4 15 You also know the encryption key is d=7 and it was determined using n=55. Decrypt this message. Assume that letters 'A' through 'Z' were initially coded using 1 through 26 and a blank was initially coded using 27.  no hand wriiten

Urgent! Answer the question below

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

Plz don't use chat gpt

21. RSA problem: given plaintext P, e, prime numbers p, q, compute ciphertext C. Decrypt C and verify you get plaintext P back.

One of the one-way functions used in public key cryptography is integer multiplication/factorization. Multiplying two integers is easy, but factoring is hard. The number 1765243 is the product of two primes. What is the smaller of the two primes? What is the largest of the two primes?

Alice sets up an RSA public/private key, but instead of using two primes, she chooses three primes p, q, and r and she uses n=pqr as her RSA-style modulus. She chooses an encryption exponent e and calculates a decryption exponent d. Encryption and Decryption are defined: C ≡ me mod n and m ≡ Cd mod n where C is the ciphertext corresponding to the message m.  Decryption: de ≡ 1 mod φ(n) | Let p = 5, q = 7, r = 3, e = 11, and the decryption exponent d = -13. n = 105 & φ(n) = 48 Q: Alice upgrades to three primes that are each 200 digits long. How many digits does n have?