Diffie-Hellman Key Exchange is a popular mathematical key exchange algorithm. It allows two parties to establish a ‘key’ over an insecure medium such as the internet. As you will see, it doesn’t matter whether the intercepting party captures each piece of transmitted information, they will not be able to break the key in any way, other than the usual brute force method.
Diffie-Hellman Key Exchange is not an encryption method, it is generally but not always used pre encryption to decide on a shared encryption key.
We will call the communicating parties Bill and Ben. Let Roger be the intercepting party. You can work out these calculations on a calculator:
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