Why do we need Hash by key? [migrated]
- by Royi Namir
(i'm just trying to find what am I missing...)
Assuming John have a clear text message , he can create a regular hash ( like md5 , or sha256) and then encrypt the message.
John can now send Paul the message + its (clear text)hash and Paul can know if the message was altered. ( decrypt and then compare hashes).
Even if an attacker can change the…