FPGAs are widely used in mission-critical environments with specific processing needs. Motivations for copying or altering sensitive data or valuable IP are abundant. Especially in government and aerospace, attacks can result in loss of IP, leakage of top-secret information, and compromised national security. A way for designers to secure their FPGAs, their sensitive data, and communications is the use of cryptography. Authenticity, integrity, and confidentiality can be guaranteed by using strong cryptographic keys rooted in the hardware of the FPGA. Synopsys PUF FPGA-X combines a Butterfly Physical Unclonable Function (PUF) with the Synopsys PUF helper data algorithms. Butterfly-shaped circuits are configured on the fabric of the FPGA to intrinsically generate the entropy needed for a strong trust anchor. Keys derived from Synopsys PUF FPGA-X are volatile and derived only when required, providing a significant high-security assurance. Since Synopsys PUF FPGA-X is part of the FPGA configuration file, it is a “soft PUF” implementation, and security functionality can be retrofitted on deployed devices, enabling remote “brownfield” installation of hardware-based security.