Early versions of the Microsoft PPTP virtual private network software used the same RC4 key for the sender and the receiver. Which attack is the network vulnerable to when a stream cipher like RC4…

The correct answer is C. ciphertext-only attack. Early versions of Microsoft's PPTP virtual private network software used the same RC4 key for the sender and the receiver (later versions solved this problem but may still have other problems). In any case where a stream cipher like RC4 is used twice with the same key, it is…

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Question

Early versions of the Microsoft PPTP virtual private network software used the same RC4 key for the sender and the receiver. Which attack is the network vulnerable to when a stream cipher like RC4 is used twice with the same key?

Options

Aforgery attack
Bmeet-in-the-middle attack
Cciphertext-only attack
Dplaintext-only attack

How the community answered

(39 responses)

A
8% (3)
B
5% (2)
C
69% (27)
D
18% (7)

Explanation

Early versions of Microsoft's PPTP virtual private network software used the same RC4 key for the sender and the receiver (later versions solved this problem but may still have other problems). In any case where a stream cipher like RC4 is used twice with the same key, it is open to ciphertext-only attack.

Topics

#RC4#stream cipher#key reuse#ciphertext-only attack

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