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TOPIC: Question about the security risk of MD5

Re: Question about the security risk of MD5 9 years 2 months ago #34157

  • S0lo
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Neat explanation sose,

It is not easy to produce a similar digest from different messages


I used to agree, unfortunately this was proven wrong for MD5, as the link above shows. Still seams to stand still for SHA2.

I will advice us to revisit the birthday parodox where mathematician worked the number of people that when
placed in thesame room will make two of the people have thesame birthday, and you know what, they arrived at the
figure 23 people- very interesting.


Nice reminder sose :), may I add that for 23 persons there is about 50% probability of two persons having the same birth date. For almost 100% probability, we need about 80 to 90 persons!!. I learned this the hard way, when I wrote a C code for a home work once :roll:
Studying CCNP...

Ammar Muqaddas
Forum Moderator
www.firewall.cx

Re: Question about the security risk of MD5 9 years 2 months ago #34194

  • sose
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solo

in some cases when you ignore leap year the number can come as low as 57 , and also the chances of having twins in the sample size affects the probabilities. i did some advance level probabilities in college and i had hard times with my professors when dealing with probabilities concerning birthday paradox. I thinks we should stay out of this math cos it will bring back bad memories from school. hahaha

Re: Question about the security risk of MD5 9 years 2 months ago #34196

  • FlipRich
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That's pretty crazy. From a non-mathematical perspective the odds seem real slim..

But math dont lie and I'm sure the equations make sense..

That birthday paradox will most likely change my common sense view on probability.
Rich
Network Engineer /CCNP, CCNA-S
Tallahassee, FL
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