On Sat, Jun 06, 2009 at 03:39:21PM +0800, jaze lee wrote:
> may be you are wright, i try , but i can not get the result.
> if a integer with m bits and another integer with n bits, if the
> multiple , there product has m+n bits or m+n-1 bits.
> 248911498900030209107 is a 21 bits number,
No it is a 21-digit *decimal* number, it is a 68-bit number in binary:
11010111111001010111010010010111010110111110010101011011110001010011
> so i think the p and q both
> are 11 bits number.
No, at least one of p or q is a <= 34-bit number, so the problem is not
actually hard for the more advanced algorithms, but should be a pain
for naive brute force trial division approach.
When you have found the factors, you'll be a bit wiser... You can try
again with an ~128-bit composite number, ... pretty soon your algorithm
will need to be rather sophisticated, and if you factor a real 1024-bit
RSA modulus without access to the private key, it will need to be better
than anything published to date.
Realistically, if you are not able to accurately count the number of
bits of a given number, you have a tough road ahead...
--
Viktor.
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