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Write Pseudocode for the password guessing algorithm:
Consider the following authentication protocol:
Client
Transmission
Host
Explanation
U, user
U à
I am user U
ß {n, DES, SHA-1}
n, random challenge, DES, SHA-1
- I have SHA_1(P(U)), where P(U) is password of user U
- Here is a random challenge n, please use DES and SHA-1 to generate a response
r=DES(n, SHA-1(P))
U, rà
Response r is the encryption of the hash of the password P of user U using key n, DES for encryption, and SHA-1 for hashing.
ß yes/no
Compare: DES-1(n, r) to SHA_1(P(U))
Can the password of user U be obtained by using an offline password guessing attack? If your answer is yes, describe the attack and write pseudocode for the password guessing algorithm. If your answer is no, describe why the protocol is resistant to an offline guessing attack.
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