Quantum Computing
Quantum Computing uses quantum phenomena such as superposition and entanglement to perform computing; currently, computers manipulate individual bits(0 or 1), but quantum computing can leverage quantum mechanical phenomena to influence information relying on bits and qubits(on or off). Regarding cryptography, it is currently tough to break a suitable key length such as the AES-128 and can take 1 billion years, according to an EETimes article. Still, with quantum computing, this number can be dropped significantly. With the current quantum computing, it is effortless to break the older cryptographic algorithms such as DES, MD5, and SHA-1. We are moving away from this encryption, but we haven't fully moved to more secured keys. It is not easy to have a quantum computer for a hacker to hack into a system. Still, with growing threats from nation-states or Advanced persistent threats (APT), multiple quantum computers can be used to hack and obtain information that can affect national security.
https://www.wsj.com/articles/the-quantum-computing-threat-to-american-security-11573411715