Exercise · ZW-RSA-CRYPTOSYSTEM-008 · ★★☆ Intermediate
If e = 5 and φ(n) = 24, what is the modular inverse d of e?
Choose one option.
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- C. 5
Explanation
Since \( 5 \cdot 5 = 25 \equiv 1 \pmod{24} \), the inverse of \( e = 5 \) is \( d = 5 \).
Review the concept: RSA cryptosystem
The RSA cryptosystem is a public-key encryption method based on the difficulty of factoring the product of two large primes. It uses Euler's theorem and modular inverses to encrypt and decrypt messages.
\[c \equiv m^{e} \pmod{n}, \quad m \equiv c^{d} \pmod{n}\]
More practice problems: rsa cryptosystem
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