Explain why the cipher ek(m)=k⊕m and dk(c)=k⊕c defined by XOR of bit strings is not secure against a chosen pl?

Explain why the cipher

ek(m)=k⊕m and dk(c)=k⊕c

defined by XOR of bit strings is not secure against a chosen plaintext attack.

Demonstrate your attack by finding the private key used to encrypt the 16-bit ci-phertextc = 1001010001010111 if you know that the corresponding plaintext is

m= 0010010000101100.

1 Answer

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  • Rahil
    Lv 5
    7 years ago
    Favorite Answer

    c = k ⊕ m

    c ⊕ m = k ⊕ m ⊕ m = k

    So k = c ⊕ m

    = 1001010001010111 ⊕ 0010010000101100

    = 1011000001111011

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