Tropical Cryptography

In tropical analysis, tropical cryptography refers to the study of a class of cryptographic protocols built upon tropical algebras. In many cases, tropical cryptographic schemes have arisen from adapting classical (non-tropical) schemes to instead rely on tropical algebras. The case for the use of tropical algebras in cryptography rests on at least two key features of tropical mathematics: in the tropical world, there is no classical multiplication (a computationally expensive operation), and the problem of solving systems of tropical polynomial equations has been shown to be NP-hard.

Basic Definitions

The key mathematical object at the heart of tropical cryptography is the tropical semiring $(\mathbb \cup \,\oplus,\otimes)$ (also known as the min-plus algebra), or a generalization thereof. The operations are defined as follows for $x,y \in \mathbb \cup \$:

$x \oplus y = \min\$

$x \otimes y = x + y$

It is easily verified that with $\infty$ as the additive identity, these binary operations on $\mathbb \cup \$ form a semiring.

References

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Cryptography
Tropical geometry