Symmetric Encryption vs Public Key Encryption – Russell Ballestrini

Topic: https://russell.ballestrini.net/symmetric-encryption-vs-public-key-encryption/

james-rb 12y, 81d ago

Good to know about the Symmetric Encryption vs Public Key Encryption

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NetEng-rb 10y, 319d ago

Looks like you made a typo or Python calculated it wrong:

n(n-1)/2= keys needed

50(50-1)/2= 1,225 symmetric keys needed.

I thought I didn't have the formula correct when I first saw your article, but I double checked it. Thanks for helping me learn that formula even better! ;)

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russell 10y, 318d ago

Yeah, it is a typo, the function I provided works. However the formula you give is a better solution because it O(1) instead of O(n) so I'm going to update the blog post with your corrections.

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unverified 5y, 349d ago

I have a question just similar to this one

The company is considering a symmetric key solution for communication between the following subsystems.

There are 3 controller devices which send commands to machines. The controller systems need to be able to communicate with each other.

There are 50 machines to control. The machines do not need to be able to communicate with each other, but need to be able to receive control messages from each of the controllers.

How many separate keys are needed in total to realize this system? How much space for key storage is needed on the controller devices? How much space for key storage is needed on the controlled machines?

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