On Jan 3, 2009, at 9:38 AM, Dorn Hetzel wrote:
Would using the combination of both MD5 and SHA-1 raise the computational bar enough for now,
I have never seen this recommended (and I do try and follow this).
or are there other good prospects for a harder to crack hash?
The Federal Information Processing Standard 180-2, Secure Hash Standard, specifies algorithms for computing five cryptographic hash functions — SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512. SHA-256 is thought to be still safe, unlike SHA-1 http://eprint.iacr.org/2008/271 http://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html and its use is recommended by RFC4509. http://tools.ietf.org/html/rfc4509 So, I would use SHA-256 if possible. (SHA-224 is a truncation of -256 - see rfc3874.) There is, BTW, a competition to find a replacement. http://csrc.nist.gov/groups/ST/hash/sha-3/index.html Regards Marshall
On Sat, Jan 3, 2009 at 9:35 AM, William Warren < hescominsoon@emmanuelcomputerconsulting.com> wrote:
Dragos Ruiu wrote:
On 2-Jan-09, at 9:56 AM, Robert Mathews (OSIA) wrote:
Joe Greco wrote:
[ .... ]
Either we take the potential for transparent MitM attacks seriously, or we do not. I'm sure the NSA would prefer "not." :-)
As for the points raised in your message, yes, there are additional problems with clients that have not taken this seriously. It is, however, one thing to have locks on your door that you do not lock, and another thing entirely not to have locks (and therefore completely lack the ability to lock). I hope that there is some serious thought going on in the browser groups about this sort of issue.
[ ... ]
... JG
F Y I, see:
SSL Blacklist 4.0 - for a Firefox extension able to detect 'bad' certificates @ http://www.codefromthe70s.org/sslblacklist.aspx
Best.
Snort rule to detect said...
url: http://vrt-sourcefire.blogspot.com/2009/01/md5-actually-harmful.html
alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"POLICY Weak SSL OSCP response -- MD5 usage"; content:"content-type: application/ocsp-response"; content:"2A 86 48 86 F7 0D 01 01 05"; metadata: policy security-ips drop, service http; reference: url, www.win.tue.nl/hashclash/rogue-ca/; classtype: policy-violation; sid:1000001;)
cheers, --dr
-- World Security Pros. Cutting Edge Training, Tools, and Techniques Vancouver, Canada March 16-20 2009 http://cansecwest.com London, U.K. May 27/28 2009 http://eusecwest.com pgpkey http://dragos.com/ kyxpgp
Everyone seems to be stampeding to SHA-1..yet it was broken in 2005. So
we trade MD5 for SHA-1? This makes no sense.