1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Number codes

  1. Jun 28, 2007 #1
    how are the secret codes for recharging the credit of a phone or the secret credit card numbers gnerated? i hrd something with prime nos. any way to decode them??????
  2. jcsd
  3. Jun 28, 2007 #2


    User Avatar
    Science Advisor

    I assume you are talking about "trap door" codes- where you can be told how to encode a messsage but that doesn't help you decode it. I don't know all the details but essentially it uses the fact that while it is relatively easy to multiply two large (prime) numbers together, it is almost impossible to factor the product without knowing the two factors to begin with. Yes, it is possible to decode them:
    (1) Know the correct factors to begin with
    (2) Use very, very powerful computer for a very, very long time.
  4. Jun 28, 2007 #3


    User Avatar
    Science Advisor
    Homework Helper

    Well, it can be cracked, but there's no smooth way to do it.
    If there were, http://www.rsa.com/rsalabs/node.asp?id=2092 [Broken] wouldn't give out $30,000 to the one who factors a number of "just" 212 decimal digits (and $200,000 for a 600+ digit number) :)
    Last edited by a moderator: May 2, 2017
  5. Jun 28, 2007 #4
    Remember what HallsofIvy was just saying XD
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Number codes
  1. Code in mail (Replies: 9)

  2. Code Cracking (Replies: 5)

  3. Cyclic codes (Replies: 4)

  4. An Unbreakable Code? (Replies: 10)