Re: sha-1 cryptography

[Saqib Ali <docbook.xml () gmail com>]

When you say "broken" do you mean a "Pre-image" attack or a
"Collision" attack. The distinction is very critical when using a
hashing algorithm in cryptography.

See definition of each type attack below:
http://en.wikipedia.org/wiki/Collision_attack
http://en.wikipedia.org/wiki/Pre-image_attack

> From your post I think you are refering to "Collision" attack.
Collision attacks are possible but it is very very complex to mount a
"USEFUL" attack using Collision.

For e.g. Pre-image attack is  required for tempering with arbitrary
(given) piece of code from a legitimate vendor that has been Digitally
Signed. A collision attack on code-signing will work only if the
attacker is writing both the innocuous and the malicious programs. In
that case why would you trust even a innocuous program from an
attacker (known mal-ware developer) ????

For simple hashing of passwd I think SHA-1 is still more than enough.

> I understand that SHa-1 cryptography has been broken by the same person who
> broke MD5, xiaoyun Wang.  So what does that mean for password security and
> credit card transactions etc.  Does that mean we will need to look for other
> stronger cryptography solutions and if yes what do you recommend, especially
> for passwords?


--
Saqib Ali, CISSP
http://www.xml-dev.com/blog/
"I fear, if I rebel against my Lord, the retribution of an Awful Day
(The Day of Resurrection)" Al-Quran 6:15

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