Database System Concepts
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Alice and Bob are using the ElGamal cipher with the parameters ?=19p=19 and ?=2α=2.
Their parameters are small and we decide to crack the cipher.
Suppose Alice is observed sending public ephemeral key ??=7kE=7 and Bob sends public key ?=17β=17.
Alice is observed transmitting the ciphertext ?=5y=5.
a) What is the masking key ??kM?
b) What is the plaintext?
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- that the ciphertexts are C = 0xbcc61793955b5eb5 and C2 = 0xdea2c2 fd718d3b77. We also happen to know that M1 A cryptography student has accidentally used the same keystream to encrypt two different messages, M1 and M2. We know Оx805d3а2029c0а386. a) What is M2 in hexadecimal? Please give your answer a leading 0x and use lowercase letters only. b) What is the keystream? Please give your answer a leading Ox and use lowercase letters only. Hint: These are all 8 byte numbers and will fit in an unsigned long type on most systems.arrow_forwardAlice and Bob are using the ElGamal cipher with = : 89 and a = 3. the parameters p Suppose Alice is observed sending public ephemeral key KE 7 and Bob sends public key = 44. = Their private keys are i a) What is the masking key km? = 81 and d = b) What is the encryption of x = 31? 28, respectively.arrow_forwardAlice and Bob are using the ElGamal cipher with the parameters p = 199 and a = 3. Their parameters are small and we decide to crack the cipher. Suppose Alice is observed sending public ephemeral key k = 103 and Bob sends public key = 136. ß Alice is observed transmitting the ciphertext y = 68. a) What is the masking key km? b) What is the plaintext?arrow_forward
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