Danny B. Carr, Jr. is the founder of Carr Digital LLC, where he builds and operates Etergis, a zero-knowledge digital continuity platform. The production case studies in this book, including the Envelope v3 post-quantum migration, are drawn from that platform’s real, shipped, and verified code. They are not a simulation built for the book.

He works in enterprise security engineering, with a focus on public key infrastructure and multi-factor authentication: issuing, monitoring, renewing, and revoking certificates, and automating the resulting toil in PowerShell and Python. Keeping a trust chain unbroken and an audit log legible is the practitioner’s-eye view this book is written from.

Before he specialized in PKI he taught cybersecurity bootcamps covering ethical hacking, network security, and vulnerability assessment. Before that he spent two decades in law enforcement and public safety. He holds the CompTIA Security+, CySA+, and CASP+ certifications and is working toward the CISSP.