Andrew Fergus
MrExcel MVP
- Joined
- Sep 9, 2004
- Messages
- 5,462
- Office Version
- 365
- 2021
- 2016
- Platform
- Windows
I have volunteered to submit another tough problem so here goes.
This is one that has puzzled mathematicians for a while and solving this may (or may not) shatter one of the foundations of public key cryptography. Public key cryptography currently relies on the inability to *efficiently* factor numbers. The public key component is essentially comprised of two very very very large prime numbers multiplied together to provide a product, which is known, but the factors are not.
The 'tough problem' is to come up with an efficient routine that will factor a very very large number.
Current wisdom states that such large numbers (these could be 100 digits longer or higher) cannot be factored efficiently - this means the computational power required to solve the problem is worth more than the message itself, or the time required to solve the problem is such that the message is now obsolete (as in many years out of date). I figure we have enough smart people here with differing backgrounds and (intentionally or not) an interest in maths to give this a go.
As an example, the following number is the product of two large prime numbers:
9,362,562,987,658,701,322,598,867
Can you find the two factors? And can you find them efficiently?
All we know is there are 2 factors, both of which are prime numbers (which excludes 1) and (in theory) there should only be one possible solution.
Note : you might consider a brute force method, which starts at the square root (say n) of the number and only tests odd numbers from n to 3. All of us are capable of coding such a brute force method, but can you code an efficient method?
Regards
Andrew
This is one that has puzzled mathematicians for a while and solving this may (or may not) shatter one of the foundations of public key cryptography. Public key cryptography currently relies on the inability to *efficiently* factor numbers. The public key component is essentially comprised of two very very very large prime numbers multiplied together to provide a product, which is known, but the factors are not.
The 'tough problem' is to come up with an efficient routine that will factor a very very large number.
Current wisdom states that such large numbers (these could be 100 digits longer or higher) cannot be factored efficiently - this means the computational power required to solve the problem is worth more than the message itself, or the time required to solve the problem is such that the message is now obsolete (as in many years out of date). I figure we have enough smart people here with differing backgrounds and (intentionally or not) an interest in maths to give this a go.
As an example, the following number is the product of two large prime numbers:
9,362,562,987,658,701,322,598,867
Can you find the two factors? And can you find them efficiently?
All we know is there are 2 factors, both of which are prime numbers (which excludes 1) and (in theory) there should only be one possible solution.
Note : you might consider a brute force method, which starts at the square root (say n) of the number and only tests odd numbers from n to 3. All of us are capable of coding such a brute force method, but can you code an efficient method?
Regards
Andrew
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