Final answer:
When Alice and Bob have the same values for the 'Extensions' in Quantum Cryptography, it means they have the same basis, which allows them to correctly transmit information and establish a shared key.
Step-by-step explanation:
In Quantum Cryptography, when Alice and Bob have the same values for the 'Extensions', it means they have the same basis. The basis is the orientation of the measuring device used to determine the value of a qubit (quantum bit). In quantum cryptography, Alice and Bob use the same basis to encode and decode the qubits, allowing them to obtain the correct key for secure communication.
For example, if Alice and Bob choose the same basis to encode and decode their qubits, they will both measure the qubits in the same way. This ensures that the information is correctly transmitted and they can establish a shared key.