Uncloneable encryption
(pp581-602)
D. Gottesman
doi:
https://doi.org/10.26421/QIC3.6-2
Abstracts:
Quantum states cannot be cloned. I show how to extend
this property to classical messages encoded using quantum states, a task
I call ``uncloneable encryption.'' An uncloneable encryption scheme has
the property that an eavesdropper Eve not only cannot read the encrypted
message, but she cannot copy it down for later decoding. She could steal
it, but then the receiver Bob would not receive the message, and would
thus be alerted that something was amiss. I prove that any
authentication scheme for quantum states acts as a secure uncloneable
encryption scheme. Uncloneable encryption is also closely related to
quantum key distribution (QKD), demonstrating a close connection between
cryptographic tasks for quantum states and for classical messages. Thus,
studying uncloneable encryption and quantum authentication allows for
some modest improvements in QKD protocols. While the main results apply
to a one-time key with unconditional security, I also show uncloneable
encryption remains secure with a pseudorandom key. In this case, to
defeat the scheme, Eve must break the computational assumption behind
the pseudorandom sequence before Bob receives the message, or her
opportunity is lost. This means uncloneable encryption can be used in a
non-interactive setting, where QKD is not available, allowing Alice and
Bob to convert a temporary computational assumption into a permanently
secure message.
Key words: encryption |