Differences between Classical and Quantum Cryptography

Classical Cryptography: Classical cryptography is based on mathematics and it relies on the computational difficulty of factorizing large number. The security of classical cryptography is based on the high complexity of the mathematical problem for the instance factorization of large number. 

Quantum Cryptography: Quantum Cryptography is based on physics and it relies on the laws of quantum mechanics. It is arising technology that emphasizes the phenomena of quantum physics in which two parties can have secure communication based on the invariability of the laws of quantum mechanics. 

Comparisons between Classical Vs. Quantum Cryptography:

Classical Cryptography	Quantum Cryptography
It is based on mathematical computation.	It is based on quantum mechanics.
It is widely used.	It is sophisticated.
Digital signature is present.	Digital signature is absent.
Bit rate depends on computational power.	Average bit rate is 1 MBPS.
Bit storage 2n n-bit strings.	Bit storage one n-bit string.
Communication range is millions of miles.	Communication range is maximum 10 miles.
Deployed and tested.	In initial stages, not tested fully.
Required up gradation as computing power increases.	It is based on physics laws.
Communication medium independent.	Communication medium dependent.
Expenditure is very less.	Expenditure is high.