Typically ad hoc networks do not have a proper infrastructure and the routing is done only through the base stations which are connecting a wired and wireless network. Does quantum cryptography protocols and QKD provide a better security for such ad hoc networks.?


QKD aims at exchanging key material to be used with encryption based on OTPs between two parties and thus to achieve perfect secrecy for transmitted messages.

There are, however, several drawbacks for practical use in a wired setting of QKD (required hardware and their vulnerability to hacks, limited distance) which does not support their use for end-to-end confidentiality over longer distances. Consequently, it is required to run QKD between single hops and thus re-encryption is required and the plaintext is revealed to the intermediate hops). For the latter, nevertheless, there are some ideas to overcome this problem.

In the non-wired setting as it is the case for MANETs, however, it is very questionable if QKD could bring any benefit. This is due to required hardware (presumably not available at the nodes) and the missing fiber optic links. Regarding the latter issue, there are some studies with single photon sources doing QKD at night over the air - presumably far away from civilisation - and at a very low bit rate, but that seems rather esoteric at the moment.

Edit As Frédèric pointed out in his comment, over the air QKD is not that esoteric as I assumed, since there are works, e.g., this one, demonstrating feasability of over the air QKD at daylight. /Edit

The most important issue from my perspective, however, in a MANET setting is due to missing infrastructure. With whom you want to exchange keys using QKD? Presumably, you do not trust your neighbours and then it makes no sense to exchange keys with them using QKD, since the respective node could read your messages. If you want to encrypt something for some far away party and therefore require end-to-end confidentiality, then you will very likely not be able to exchange a key using QKD with this party. So why using QKD in such a setting (besides the above mentioned problems)? Then you could pre-distribute key material, but using OTPs will be impractical due to the large key material required. So you will very likely drop the perfect secrecy requirement and come back to traditional (secret key or public key) encryption schemes.

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    $\begingroup$ Nice answer. I just have a minor point : daylight QKD open air has been done since at least 2000 arxiv.org/abs/quant-ph/0001088 , so it's not only at night and far away from civilisation. $\endgroup$ – Frédéric Grosshans Dec 16 '13 at 14:44

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