I flagged this question to be duplicate of this one and my report was marked as helpful:



But I do not see any action taken. I suppose the duplicate question should be closed. Then how is the flagged question still open if my report was helpful? 


Question: Can you make a hash out of a stream cipher?
Answer: A Pseudo Random Generator (PRG) and a hash function are both Pseudo Random Functions (PRFs), but they have different security considerations. (At least, historically they do. Moving forward some of them may be more closely aligned.) Due to this, building a hash from an existing PRG designed under older security constraints probably isn't a good idea for the intuitive construction of using the plaintext as the key to the PRG and the PRG output as the hash. See this nice summary: Why stream ciphers shouldn’t be used for hashing.