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Experiment 9 - Understanding ElGamal public key cryptosystem

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What is the purpose of the ElGamal private key in the decryption process?

a: To generate a random number Explanation

Explanation

b: To compute temporary values Explanation

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c: To compute the shared secret Explanation

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d: To select a generator of the group Explanation

Explanation

How is the original message recovered during ElGamal decryption?

a: Using the private key Explanation

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b: Multiplying by the shared secret Explanation

Explanation

c: Computing the inverse of the temporary value Explanation

Explanation

d: Exponentiating the ciphertext Explanation

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In ElGamal encryption, why is it essential for the random number 'k' to be relatively prime to (p-1)?

a: To ensure a unique session key Explanation

Explanation

b: To prevent key leakage Explanation

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c: To avoid weak key generation Explanation

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d: To achieve better compression Explanation

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ElGamal provides semantic security under:

a: Chosen plaintext attack Explanation

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b: Known plaintext attack only Explanation

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c: Ciphertext-only attack Explanation

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d: Brute force attack only Explanation

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Why is randomness important in ElGamal encryption?

a: To reduce message size Explanation

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b: To ensure the ciphertext is unique each time Explanation

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c: To speed up decryption Explanation

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d: To make the public key stronger Explanation

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Which statement is true about ElGamal encryption?

a: The same ciphertext is generated for the same message every time Explanation

Explanation

b: The ciphertext changes each time even for the same message Explanation

Explanation

c: Encryption does not require the receiver’s public key Explanation

Explanation

d: Decryption can be done without the private key Explanation

Explanation

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