Cryptography question

[qwsxc]

Hey there
Can anyone inform me of a math problem that is easy going in one direction but difficult in the other?
In the sense of the encryption example using colours.(bob send yellow to alice and eve steals yellow, bob sends yellow mixed with green to alice and eve steals the mixture, alice sends red mixed with yellow to bob and eve steals the second mixture, bob and alice mix the colour they mixed with yellow with the mixture they got and they have a key that eve doesn't know about.)

Thanks!

[1715403828]

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[1715403828]

1715403828

[1715403828]

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[1715403828]

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[cbeast]

Are you talking about an algorithm used to salt a key?

[qwsxc]

Are you talking about an algorithm used to salt a key?

I don't think so, though I may be confused, I have been researching diffie hellman key exchange

[qwsxc]

Okay, done some more research and thought about the problem...
If eve=the eavesdropper, bob and alice= the people trying to communicate
the publicly shared number is 120
bob chooses a random number(4) computes 120/his number (30) and publicly sends this to alice,(eve also gets it)
alice does the same as bob using 6
the number bob received/the number he used to divide 120=5
alice does the same and gets 5
eve cannot make 5 from combinations of her numbers


can someone please tell me if this is a fluke, if there are problems with it or if it would work?

[deepceleron]

The basis of RSA public key cryptography serves as the best example and is that of prime numbers - it is easy to find two very large prime numbers and multiply them together, but it is very hard to factor the product back to the numbers that were used.