systemd/man/uki.conf.example

[UKI]
SecureBootPrivateKey=/etc/kernel/secure-boot-key.pem
SecureBootCertificate=/etc/kernel/secure-boot-certificate.pem

[PCRSignature:initrd]
Phases=enter-initrd
PCRPrivateKey=/etc/systemd/tpm2-pcr-private-key-initrd.pem
PCRPublicKey=/etc/systemd/tpm2-pcr-public-key-initrd.pem

[PCRSignature:system]
Phases=enter-initrd:leave-initrd enter-initrd:leave-initrd:sysinit
       enter-initrd:leave-initrd:sysinit:ready
PCRPrivateKey=/etc/systemd/tpm2-pcr-private-key-system.pem
PCRPublicKey=/etc/systemd/tpm2-pcr-public-key-system.pem