  The software engineering community is facing challenges from quantum
computers (QCs). In the era of quantum computing, Shor's algorithm running on
QCs can break asymmetric encryption algorithms that classical computers
practically cannot. Though the exact date when QCs will become "dangerous" for
practical problems is unknown, the consensus is that this future is near. Thus,
the software engineering community needs to start making software ready for
quantum attacks and ensure quantum safety proactively.
  We argue that the problem of evolving existing software to quantum-safe
software is very similar to the Y2K bug. Thus, we leverage some best practices
from the Y2K bug and propose our roadmap, called 7E, which gives developers a
structured way to prepare for quantum attacks. It is intended to help
developers start planning for the creation of new software and the evolution of
cryptography in existing software.
  In this paper, we use a case study to validate the viability of 7E. Our
software under study is the IBM Db2 database system. We upgrade the current
cryptographic schemes to post-quantum cryptographic ones (using Kyber and
Dilithium schemes) and report our findings and lessons learned.
  We show that the 7E roadmap effectively plans the evolution of existing
software security features towards quantum safety, but it does require minor
revisions. We incorporate our experience with IBM Db2 into the revised 7E
roadmap.
  The U.S. Department of Commerce's National Institute of Standards and
Technology is finalizing the post-quantum cryptographic standard. The software
engineering community needs to start getting prepared for the quantum advantage
era. We hope that our experiential study with IBM Db2 and the 7E roadmap will
help the community prepare existing software for quantum attacks in a
structured manner.
