What is the difference between post-quantum cryptography and traditional cryptography?

Post-quantum cryptography (PQC) and traditional cryptography differ primarily in their resistance to attacks from quantum computers.

Traditional cryptography relies on mathematical problems like integer factorization (RSA) or discrete logarithms (ECC), which are computationally hard for classical computers but can be efficiently solved by quantum algorithms like Shor's algorithm. This makes traditional systems vulnerable to future quantum threats.

Post-quantum cryptography, on the other hand, uses quantum-resistant algorithms based on problems believed to be hard even for quantum computers, such as lattice-based cryptography, hash-based signatures, or code-based cryptography. These methods ensure long-term security against quantum attacks.

Example:

• Traditional: RSA encryption, widely used for secure web browsing (HTTPS), is vulnerable to quantum decryption.
• PQC: CRYSTALS-Kyber (a lattice-based key exchange algorithm) is a NIST-selected PQC standard for secure communication in a post-quantum era.

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