QKD is a mean to generate a same random code on two seperate devices
- two entangled photons are sent to the devices .
-The polarisation of the two phtons is not decided in the directions in which they will be read, until they reach the devices.
-Upon their arrival , the polafrisation gets randomly decided. The two photons being entangled, the polarsation in which they are read by the two devices is nontheless complimentary.
- a same random code is therefore generated on the two devices
- then the two parties exchange an e-signature of the recveived codes.
the party receiving the random code needs to make sure that the same code has also been received by the other party, and not by another party that it does not know.
for instance by sending a key to one of the parties and examinig the signature
because our random hash signatures use One Time Keys.
and the size of the keys used for the e-signature is a lot smaller than the size of the generated keys