Uncloneable Cryptography

INTRACTABLE COMPUTATIONAL PROBLEMS are a barrier
for algorithm designers. Cryptographers are modern
lemonade makers. Their lemons are these intractable
problems, which they squeeze into sweet lemonade:
secure cryptographic protocols. Why is a lemon even
required? Because it lets us assume there is something
an adversary cannot do. Intractable problems can give
the honest user an advantage: for example, the honest
user can multiply two large primes. The honest user
knows the prime factors of the resulting number; yet,
it is widely believed that a classical adversary cannot
(efficiently) find these factors.
Cryptographers have been squeezing this
computational intractability lemon since the 1970s.
Are there any other lemons on which cryptography
could be based? Quantum mechanics has quite a few
peculiarities. One notable example is the no-cloning
theorem, which states that quantum information
cannot be cloned. Uncloneable cryptography—the
main focus of this review—uses the no-cloning lemon
as its main ingredient. For a broader perspective, see
Figure 1 on page 80.