Provides key security terms and definitions crucial for understanding trustworthy systems, serving as a reference for foundational concepts and terminology used throughout the chapter.
The following terms are commonly used in the trustworthy systems:
-
Attestation: Mechanism used to confirm the software's integrity. The verifier trusts the attested data because it is signed by a TPM whose key is certified by the Certificate Authority (CA).
-
Attestation Identity Key (AIK): A restricted key used for signing attestation requests.
-
Bootloader: Code that runs before any operating system, capable of loading the OS kernel and providing commands for debugging or modifying the kernel environment.
-
Certificates and Keys in Trust Anchor module (TAm):
-
Image signing certificate: X.509 certificate for validating signatures of GRUB, initrd, kernel, and kernel modules.
-
IOS-XR Key: Public key certificate signed by the Key Enrollment Key (KEK), common to all Cisco 8000 Series routers, used for signing GRUB, initrd, kernel, and kernel modules.
-
RPM key: Used for signing RPM packages.
-
IMA public key certificate: Used to validate Integrity Measurement Architecture (IMA) signatures of files.
-
BIOS or firmware capsule update key: Used to sign the outer capsule for BIOS or firmware updates; same as the secure boot key.
-
Platform key (PK) and Key Enrollment Key (KEK): Public keys and certificates for managing other keys in the TAm.
-
LDWM Key: Stored in the hardware trust anchor module in Cisco IOS XR7, used for validating BIOS.
-
-
Golden ISO (GISO): Image containing the base Linux distribution artifact (ISO), packages, and configuration files serving as a baseline across all servers. The Cisco IOS XR7 GISO image includes IOS XR RPMs, third-party RPMs, ztp.ini, and secure ZTP certificates.
-
GRand Unified Bootloader (GRUB): Boot loader package that loads the kernel, supports multiple operating systems, and starts at system boot.
-
Hash Function: Function used to map data of arbitrary size onto data of fixed size.
-
Initramfs: Set of directories bundled into a compressed cpio archive, loaded at boot time by the boot loader along with the kernel.
-
initrd (initial RAM disk): Initial root file system mounted before the real root file system becomes available; loaded as part of the kernel boot procedure.
-
JTAG: Hardware interface enabling communication with chips on a board for debugging, programming, and testing embedded devices.
-
Nonce Value: Arbitrary number used only once in cryptographic communications, preventing replay attacks by ensuring uniqueness.
-
Platform Configuration Register (PCR): Shielded register/memory region holding hash operations; initialized to a known value at power-up and typically cannot be reset.
-
PCR Extend: Operation for updating PCR value:
PCR[x]new = hash ( PCR[x]old || hash ( measurement value ) )
-
Trust Anchor module (TAm): Cisco hardware module that verifies device authenticity and provides additional security services.
-
Trusted Platform Module (TPM): Specialized chip storing RSA encryption keys; used for hardware authentication and key generation based on Endorsement Key and owner-specified password.
-
Root of Trust for Storage: TPM 2.0-compliant PCRs form the Root of Trust for Storage.