Compute CBC-MAC for a message of 16 bits, “ABCD” (in Hexa). Assume a block size of 8 bits with an IV=C9 (in hexa). For simplicity, assume the encryption to be a simple XOR of the key with the plaintext. Let the encryption key be D8 (in Hexa).
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Compute CBC-MAC for a message of 16 bits, “ABCD” (in Hexa). Assume a block size of 8 bits with an IV=C9 (in hexa). For simplicity, assume the encryption to be a simple XOR of the key with the plaintext. Let the encryption key be D8 (in Hexa).
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- Compute CBC-MAC for a message of 16 bits, “ABCD” (in Hexa). Assume a block size of 8 bits with an IV=C9 (in hexa). For simplicity, assume the encryption to be a simple XOR of the key with the plaintext. Let the encryption key be D8 (in Hexa). (Hint: Divide the message into blocks of 8 bits each; XOR each block with the previous cipher output; then encrypt this with the key. For the first block, XOR it with IV.a. Compute CBC-MAC for a message of 16 bits, “8642” (in Hexa). Assume a block size of 8 bits with an IV=F1 (in hexa). For simplicity, assume the encryption to be a simple XOR of the key with the plaintext. Let the encryption key be B4 (in Hexa). (Hint: Divide the message into blocks of 8 bits each; XOR each block with the previous cipher output; then encrypt this with the key. For the first block, XOR it with IV. Details in pages 325-326 Ch.12 of the textbook) b. Suppose Alice computes the Secret prefix MAC (page 322: secret prefix MAC(x) = h(key || x)) for the message ”AM” (in ASCII) with key “G” (in ASCII) that both Alice and Bob know. The hash function that is used is h(x1x2x3)= g(g(x1 XOR x2) XOR x3 ) where each xi is a character represented as 8 bits, and g(x) is a 8-bit string that is equal to the complement of bits in x. For example, g(10110011) = 01001100. The MAC is 8 bits. (8-bit ASCII representation of the characters is given below.) What is the Secret prefix MAC…Computer Science With the CBC/OFB/CFB/CTR mode: (a) if there is a single bit transmission error in block C3 of the ciphertext, which plaintext blocks are affected? CBC and CTR (b) Suppose that there is a bit error in the source version of P1. Through how many ciphertext blocks is this error propagated? What is the effect at the receiver?
- Msg3. B→A : B, N1, Ks, Message2, h(B, N1, Message2) Whereas: h(m) represents the digest of the message (m). {m}{K} represents the encryption of message (m) using the key (K) PK is public key N1 is a random number. 1. What are the main problems in Msg3?With the ECB mode, if there is an error in a block of the transmitted ciphertext, only the corresponding plaintext block is affected. However, in the CBC mode, this error propagates. For example, an error in the transmitted C1 obviously corrupts P1 and P21. 1. Are any blocks beyond P2 affected? 2. Suppose that there is a bit error in the source version of P1. Through how many ciphertext blocks is this error propagated? What is the effect at the receiver? (Encryption algorithms question)N blocks of plaintext (P1 to PN) are being encrypted in CFB mode into ciphertext (C1 to CN). Assume that two bits of C3 are erroneous (their binary values have flipped). What bits of C3, C4, and C20 are erroneous?
- Suppose we will use Advanced Encryption Standard (AES) to encrypt a block of plaintext and the known round key for round 7 is: B5 8D BA D2 31 2B F5 60 7F 8D 29 2F EA D2 73 21 What is the third word (i.e. the third 4 bytes) of the round key for round 8?Give encryption or decryption of these hexadecimal messages using the one-time pad algorithm, giving the result in hexadecimal also. You may wish to convert to binary first. a. m = 0xdeadbeef, K = 0x4ea04002, c = ? b. c = 0x84848484, K = 0xffffffff, m = ? c. c = 0x104557ce, K = 0xdabbad00, m = ?We use DES in cipher feedback mode (CFB) to encrypt a plaintext m = m1m2 ...m100 into a ciphertext c1c2 ...c100, where each mi is 8-bit long. The ciphertext is sent to Bob. If c15 and c25 are missing and c8 and c88 are received as c8' and c88' wrongly, what mi’s can B compute correctly from the received ciphertext?
- Suppose we use a checksum scheme based on the addition of successive 8-bit fields rather than 16-bit fields as in the Internet Transport layer. Now suppose that the following 3 bytes are received, in which the last bytes is the checksum field. 0 1 0 1 0 0 1 1 1 1 0 1 0 1 0 0 1 1 0 1 0 1 1 1 Does the receiver detect an error that might have occurred during the transmission of these three bytes?a. Compute CBC-MAC for a message of 16 bits, “8642” (in Hexa). Assume a block size of 8 bits with an IV=F1 (in hexa). For simplicity, assume the encryption to be a simple XOR of the key with the plaintext. Let the encryption key be B4 (in Hexa).The very last block of a message encrypted with AES-256 in CBC mode is 15 bytes long and ends with the bytes: 0102030405060708090a0b0c0d0e0f When padded in accordance with PKCS #7 with 16-byte blocks, what is the complete value of the last block? *Please explain how you have solved this, thank you!!