Take the 2-minute tour ×  I understand that the MD5 algorithm
isn't collision resistant, and that collisions between data of
arbitrary size can be found with more efficient methods than
brute-forcing.  However, I have read that MD5 is still a safe
algorithm for, say, password hashing, because no method has been
found to reverse-engineer the hashing algorithm.  In what cases
could a hacker exploit a webpage or other secure client which
was using MD5 for security?  share|improve this question  3
Answers 3  Consider a security system where users each have
their own secret key, which is known by a server. When they send
commands to the server, they hash the command and their secret
key and then send the command the hash. The server does the same
hash and confirms that the command was hashed with your secret
key. This is basically what OAuth does (except they use SHA-1).
If an attacker can generate hashes without your secret key, they
can send commands as you without getting access to your key.
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