Cryptographically Relevant Quantum Computer Primer
The NSA defines a Quantum Computer that is used to break encryption as a “Cryptographically Relevant Quantum Computer” (CRQC).
This special purpose CRQC has the potential to brute force attack classical cryptography.
On January 22, 2022, the United States President signed a memorandum highlighting the importance of upgrading to NSA current post-quantum standards, saying the following:
“Within 60 days of the date of this memorandum, the NSA shall revise and make available to Chief Information Officers the CNSS Advisory Memorandum 01-07 (Information Assurance Cryptographic Equipment Modernization) and any associated enclosures and relevant references regarding modernization planning, use of unsupported encryption, approved mission unique protocols, quantum resistant protocols, and planning for use of quantum resistant cryptography where necessary. Within 180 days of the date of this memorandum, agencies shall identify any instances of encryption not in compliance with NSA-approved Quantum Resistant Algorithms or CNSA.”
NSA FAQ (PDF) on Quantum Computing and Post-Quantum Cryptography