In a system an RSA algorithm with p=5 and q=11, is implemented for data…
2014
In a system an RSA algorithm with p=5 and q=11, is implemented for data security. What is the value of the decryption key if the value of the encryption key is 27?
- A.
3
- B.
7
- C.
27
- D.
40
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Correct answer: A
First, calculate Euler's totient function phi(n) = (p-1)(q-1). With p=5 and q=11, phi(n) = 4 * 10 = 40. The decryption key d must satisfy e*d ≡ 1 (mod phi(n)). Substituting the values, we need to find d such that 27d ≡ 1 (mod 40). Testing values, we find that 27 * 3 = 81. Since 81 mod 40 equals 1, the decryption key d is 3.
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