I'm not sure what you mean by this. mrpollo recommended using MD5 as a checksum before executing jQuery to ensure that the CDN hasn't been compromised. For instance jQuery 1.8.0's checksum is cd8b0bffc85bb5614385ee4ce3596d07. I was under the impression that MD5 isn't malleable enough to create a non-trivial malicious script with the same hash.