312-50V10 · Question #552
A hacker was able to sniff packets on a company's wireless network. The following information was discovered: The Key 10110010 01001011 The Cyphertext 01100101 01011010 Using the Exlcusive OR, what…
The correct answer is B. 11010111 00010001. XOR decryption works by XORing the ciphertext with the key, since the operation is its own inverse. Calculating 01100101 01011010 XOR 10110010 01001011 bit-by-bit yields 11010111 00010001.
Question
A hacker was able to sniff packets on a company's wireless network. The following information was discovered:
The Key 10110010 01001011 The Cyphertext 01100101 01011010 Using the Exlcusive OR, what was the original message?
Options
- A00101000 11101110
- B11010111 00010001
- C00001101 10100100
- D11110010 01011011
How the community answered
(22 responses)- A9% (2)
- B68% (15)
- C5% (1)
- D18% (4)
Why each option
XOR decryption works by XORing the ciphertext with the key, since the operation is its own inverse. Calculating 01100101 01011010 XOR 10110010 01001011 bit-by-bit yields 11010111 00010001.
00101000 11101110 is not the result of XORing the provided ciphertext bytes with the provided key bytes - no valid bit-by-bit XOR of these two values produces this output.
In XOR-based encryption, plaintext XOR key = ciphertext, and ciphertext XOR key = plaintext because XOR is self-inverse. Performing the operation on each bit pair across both bytes - 01100101 01011010 XOR 10110010 01001011 - produces 11010111 00010001, confirming B as the original message.
00001101 10100100 does not result from XORing the given ciphertext with the given key - the arithmetic does not produce these bit values.
11110010 01011011 is not produced by XORing the specified ciphertext and key - it would require a different input pair entirely.
Concept tested: XOR cipher symmetric decryption operation
Source: https://csrc.nist.gov/glossary/term/exclusive_or
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