Computer Networks - Computer Networks Section 1
57. Let h be a cryptographic hash function. Which of the following is not a property of h?
- A
Given hash y, it should be computationally infeasible to find x such that y = h(x).
- B
Given hash y and a message x such that y = h(x), it should be computationally infeasible to find x'≠ x such that h(x') = h(x) = y.
- C
Given hash y, it should be easy to find x such that y = h(x).
- D
It should be computationally infeasible to find x', x such that h(x') = h(x)
- Option : C
- Explanation : INPUT: Domain parameters (p=283,q=47,g=60) INPUT: user's private key, a=24 INPUT: Message M with message digest h=Hash(M)=41. user chooses a random k=15 in the range [1,q−1] user computes X=gkmodp=6015mod283=207 and r=Xmodq=207mod47=19. r≠0 so continue. user computes k−1modq=15−1mod47=22. user computes h=Hash(M)=41. user computes s=k−1(h+ar)modq=22(41+24⋅19)mod47=30. s≠0 so continue. user's issues the message M and signature (r,s)=(19,30).
