A US$-$based healthcare startup is building an interactive diagnostic tool for COVID$-19$ related assessments. The users would be required to capture their personal health records via this tool. As this is sensitive health information, the backup of the user data must be kept encrypted in S$3.$ The startup does not want to provide its own encryption keys but still wants to maintain an audit trail of when an encryption key was used and by whom.Which of the following is the BEST solution for this use$-$case?