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Can anyone help me with the name of the digital footprint law? All I know is that it is named after its discoverer much like Moore's Law is. This is a computer science law that states for the purposes of encryption that all operations on a computer can be reversed which means that in theory all codes can be cracked. I had this information but errantly lost it. I could be mistaken but I think I first learned of this law in the Jeffery Deaver novel, "The Blue Nowhere" or perhaps the Dan Brown novel, "Digital Fortress". I know those aren't exactly academic textbooks but that may help jog someone's memory.

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    I have heard of this "law", and it has been referenced a few times in answers here over the years. If it's the same thing, the "law" is not a law and faulty in its understanding of cryptography. – schroeder Aug 30 at 6:35
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    I just googled "digital fortress all encryption can be broken" and got "bergofsky principle" as the hit. – schroeder Aug 30 at 6:40
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    From Course Hero, the Bergofsky Principle "clearly stated that if a computer tried enough keys, it was mathematically guaranteed to find the right one. A code’s security was not that its pass-key was unfindable but rather that most people didn’t have the time or equipment to try." Which is sort-of-true, if we're allowed to discount that the heat-death of the universe might happen first. – TripeHound Aug 30 at 7:54
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    Just a tip: Don't ever take anything from a Dan Brown novel to be based in fact. Digital Fortress is perhaps the stupidest compilation of nonsense ever published. – Xander Aug 30 at 12:58
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    The existence of information-theoretic secure algorithms such as the one-time pad trivially disproves this "law". – AndrolGenhald Aug 30 at 18:02
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There is no such law, and the claim itself is false.

In a cryptography, there are irreversible operations such as XOR, which destroys information by taking two inputs but having only one output. There are also reversible operations, such as NOT, which takes one input and gives one output. It would be necessary to design a special, reversible version of otherwise irreversible operations. An example is CCNOT, which takes three inputs and has three outputs. If this is done, and all the outputs are preserved, then indeed secret cryptography would become impossible.

This is a computer science law that states for the purposes of encryption that all operations on a computer can be reversed which means that in theory all codes can be cracked.

Counterexample: I have chosen two secret numbers a and b such that a + b = 37. Try to reverse it.

For a cryptographic counterexample, consider the one-time pad (OTP). It is perfectly secret because, given some ciphertext, the probability that it is the encryption of a given plaintext message is exactly equal to the probability that it is the encryption of another plaintext message. This statement holds true for all possible plaintexts and ciphertexts, without exception, when using a uniformly random key. The OTP theorem states that, if plaintext p is a variable with any distribution over {0,1}n and k is a uniform random variable over {0,1}n, then the ciphertext c = p ⊕ k is a uniform random variable over {0,1}n.

This answer only describes logical reversibility and not thermodynamic reversibility, which is another subject entirely.

  • Hey thanks to all for your answers. I didn't really think its a law anymore than I think Moore's Law is an actual law. Its just an observation that puts us in a pigeonhole to keep doubling our computational prowess. I got ran off physics stack exchange where no one could helpIm gladf i found yall. Awesome. Thanks for the free education. – Dreamer Sep 2 at 0:55
  • @Dreamer Well at least Moore's law is a relatively accurate observation. This one is entirely false. Remember if this answered your question, please mark the answer as "accepted". :) – forest Sep 2 at 0:59

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