The ATM card that I had (note Mods I no longer have this account so there is no risk here) on my business account was not used much so I wrote the PIN on the card in an encryption.
I’ll add that it is a four digit number.
The number I wrote on the card is:
49236913293574598
I know that a PIN is not to be written on the card, but I did not really write the number on the card and do not believe that anybody could figure it out. Since the group here has more KSA’s than the average thug, I thought it would be interesting to put my code to the test.
There is a factual answer to this and I will post it after the TMs have had a crack at it.
There is no solution that’s better than random guessing. The problem is, your algorithm is private, so giving us your number doesn’t really give us any information.
For example, let’s say that I tell you that I’ve encrypted my 4-digit PIN, and the result is 2222. This number could be the product of any number of algorithms:
PIN#+1
PIN#-1
PIN#*2
(PIN#*13 mod 11)^4
…well ok, not that last one. But do you see why we don’t have enough info to solve the problem?
All that said, if you put a gun to my head I’d choose 4627
I see Nobody’s Fool’s reasoning that each number comes after each 9… so my guess opposite of his would be 4625.
Then again, that is boring… if you take each number and multiply it by the next number all of them beautifully go into 3 except for 5745, which is all together.
I have come up with all sorts of crazy schemes on figuring this one out. SO in answer to your question… I have no idea and I hate you. I wish I never would have found this thread because I have actually fallen down stairs marvelling at Fibonacci numbers. It was an excellent number theory class…
Since your algorithm is not immediately obvious, finding a random set of numbers generated from a random set of other numbers is rather impossible.
OTOH, my friend and I had nothing better to do for 10 minutes, so:
After each 9: 2138
Before each 9: 4625
Using first 4 digits as index: 3292
Using first 4 digits as index into next 13: 3791
Use current digit as look-ahead value for next digit: 4634
Here’s another guess (if multiple guesses are allowed). Since my last one was based on a simple algorithm, I decided to try something more complex.
The sequence 49236913293574598 is 17 digits long, and 17 is a prime number.
The number sequence can also be broken into four blocks, each of which also contains a prime number of digits (representing the first four primes, by the way).
49 236 91329 3574598
Notice that there are four groups: One for each digit of the PIN. Anyone with a basic understanding of prime numbers could reach this point with with no need for fancy calculations. So my next part will be just as simple. I’m going to add the digits in each block, and keep adding until I get a single digit. So:
