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R-18 suppose that asymmetric cryptosystem with 32-bit key length is used to encr

ID: 3668883 • Letter: R

Question

R-18 suppose that asymmetric cryptosystem with 32-bit key length is used to encrypt message written in English and encoded in ASCII. Given that keys are short, an attacker is using a brute-force exhaustive search method to decrypt a cipher text of bytes. Estimate the probability of uniquely recovering the plaintext corresponding to the cipher text for the following values of t: 8, 64, and 512. I want to calculate the probability. R-18 suppose that asymmetric cryptosystem with 32-bit key length is used to encrypt message written in English and encoded in ASCII. Given that keys are short, an attacker is using a brute-force exhaustive search method to decrypt a cipher text of bytes. Estimate the probability of uniquely recovering the plaintext corresponding to the cipher text for the following values of t: 8, 64, and 512. I want to calculate the probability. R-18 suppose that asymmetric cryptosystem with 32-bit key length is used to encrypt message written in English and encoded in ASCII. Given that keys are short, an attacker is using a brute-force exhaustive search method to decrypt a cipher text of bytes. Estimate the probability of uniquely recovering the plaintext corresponding to the cipher text for the following values of t: 8, 64, and 512. I want to calculate the probability.

Explanation / Answer

Solution:

k = (21.25)t

= 21.25*t

N = (28)t

= 28*t

P = (k/N)

= (21.25*t/28*t)

= 2(1.25-8)*t

P = (1/26.75*t)…(i)

P = (k/26.75*t)

= (232/26.75*8)

= (1/254-32)

= (1/222).

P = (k/26.75*t)

= (232/26.75*64)

= (1/2432-32)

= (1/2400).

P = (k/26.75*t)

= (232/26.75*512)

= (1/22656-32)

= (1/22624).

As the t-character string increases as t:64 and t:512, the probability goes down exponentially.