The SHA hash functions are a set of cryptographic hash functions designed by the National Security Agency (NSA)
http://en.wikipedia.org/wiki/SHA_hash_functions You should listen to episode to ep #31 through #35 of Security Now - provides a good background on keys, hashes etc. http://www.grc.com/securitynow.htm#35 -------- Owner Nigredo Studios http://www.nigredostudios.com --- On Wed, 8/7/09, Saul Rennison <[email protected]> wrote: From: Saul Rennison <[email protected]> Subject: Re: [hlcoders] Access reception to hlcoders forum To: "Discussion of Half-Life Programming" <[email protected]> Received: Wednesday, 8 July, 2009, 5:57 PM Wait. Is a hash a form of encryption (such as MD5) / encoding (Rot13), which is potentially reversible, whereas checksums are purely a way of providing a shorter output semi-unique to the input. Amirite? Sent from my iPhone On 8 Jul 2009, at 02:52, Bob Somers <[email protected]> wrote: > SHA-1 is not a checksum, it's a hash. A checksum (like a CRC32, CRC16, > etc.) is different from a hash. > > Also, what Jonas and Harry mentioned applies. Even if it is a hash and > not a checksum, it could easily just be replace unless it is signed. > > --Bob > > > > On Tue, Jul 7, 2009 at 2:01 PM, Dave Gomboc<[email protected]> > wrote: >>> >>> Checksums really don't provide security against tampering, as they >>> are >>> too easy to manufacture. They're more often used to detect casual >>> corruption errors like those that could be introduced during network >>> transmission. >>> >>> --Bob >>> >> >> I'm not sure what your definition of "easy to manufacture" is, but >> I'm not >> aware that the frequently-used SHA-1 would qualify as such. >> Finding a >> collision has been proven to be possible faster than via brute >> force attack, >> but I would think that doing so with contrived data that must also >> serve as >> a working substitute for the original data would still be pretty >> difficult >> (as of July 2009, anyway). Also, there's better checksums than >> SHA-1 that >> could be used in its stead. >> >> Dave >> _______________________________________________ >> To unsubscribe, edit your list preferences, or view the list >> archives, please visit: >> http://list.valvesoftware.com/mailman/listinfo/hlcoders >> >> > > _______________________________________________ > To unsubscribe, edit your list preferences, or view the list > archives, please visit: > http://list.valvesoftware.com/mailman/listinfo/hlcoders > _______________________________________________ To unsubscribe, edit your list preferences, or view the list archives, please visit: http://list.valvesoftware.com/mailman/listinfo/hlcoders ____________________________________________________________________________________ Access Yahoo!7 Mail on your mobile. Anytime. Anywhere. Show me how: http://au.mobile.yahoo.com/mail _______________________________________________ To unsubscribe, edit your list preferences, or view the list archives, please visit: http://list.valvesoftware.com/mailman/listinfo/hlcoders
