Feature #7783: Add support for sqrt of very large numbers

• Status: Closed
• Assignee: -
• Target version: -

[spastorino (Santiago Pastorino)]

Currently ...

irb(main):001:0> Math.sqrt(2**6456)
=> Infinity

I wanted to do something like this to show an example of how RSA could break RSA the public modulus N is generated incorrectly.

In Python you can do it using http://code.google.com/p/gmpy/
The issue is also described here http://webcache.googleusercontent.com/search?q=cache:on5z4JS3iUcJ:stackoverflow.com/questions/8226087/how-do-i-get-math-sqrt-to-return-a-bignum-and-not-a-float+&cd=3&hl=en&ct=clnk

[spastorino (Santiago Pastorino)]

/RSA the/when/

[zzak (zzak _)]

=begin
Hello Mr. Pastorino!

It seems to work when I use the mathn library, which implements sqrt(3)

(({irb(main):001:0> require 'mathn' #=> true}))

(({irb(main):002:0> Math.sqrt(2**6456) #=> 53067179215503898168575338070}))
=end

[spastorino (Santiago Pastorino)]

Hey zzak, had no idea about that. Thanks!
So we can close this one.

[MartinBosslet (Martin Bosslet)]

• Status changed from Open to Closed

Nice find, Zachary!

I happened to talk with Santiago about this. Closing...

[zzak (zzak _)]

Anytime!