On 15-Apr-07, at 7:02 AM, William Squires wrote: > Note that a hash function is NOT - in general - inverse-able. i.e. > a hash function, such as MD5, is designed to be difficult to obtain > an inverse of. So don't mistakenly use a hash function, or you'll > never get your original (plain-text) back! A CRC (Cyclic-Redundancy > Check) is another type of hash.
And it's very likely that the same MD5 will come from different bodies of text. It's probably provable that this is the case. Since it only uses 128 bits EVERY possible sequence of bytes has to be reduced to only 128 bits. There are, most assuredly, more that 2^128 sequences of bytes so some of those byte sequences will end up with similar MD5 checksums from different byte sequences. That's at least one reason that you cannot get the inverse. There is no unique inverse. _______________________________________________ Unsubscribe or switch delivery mode: <http://www.realsoftware.com/support/listmanager/> Search the archives: <http://support.realsoftware.com/listarchives/lists.html>
