I was recently viewing a website and saw its certificate info as follows:
Given that MD5 is badly broken and not recommended for hashing, how good is it for use in TLS? And why?
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In TLS, MD5 is used as the compression function for HMAC. The best current security proof for HMAC does not require its compression function to be collision-resistant, so HMAC-MD5 is still considered secure (if distasteful).
TLS 1.0 and RC4 are more disconcerting than MD5 in this case.
That this page is using MD5 is bad. Even SHA-1 wouldn't be nice.
But hashing and authentication are two different things and as far as I can see this site uses HMAC-MD5, which does't need the collision resistance although this would be nice to have. This was already discussed here.
Well, the cipher suite this site is using to connect to you is pretty bad. Three properties you don't want: