1. A computer-implemented method for negotiating quantum data keys between first and second entities, the method comprising: performing a mutual authentication between the first and second entities; in response to the mutual authentication succeeding, receiving, by the first entity, one or more sets of key-generation parameters from the second entity; in response to validating the sets of key-generation parameters, sending an acknowledgment message to the second entity; and extracting, from a quantum string shared between the first and second entities, one or more quantum data keys based on the key-generation parameters, wherein a respective quantum data key comprises a number of bits extracted from the quantum string.