What is Root of Trust

Set of security primitives that form the foundation for building more advance security features

Industry fragmentation…

There are many solutions...

Many deficiencies…

Root of Trust – State of the Industry

Consistency of security primitives that underpin higher-level capabilities and operational behaviors.

Caliptra (Spanish, ’root tip’) an open-source silicon Root of Trust

Transparency of security mechanisms of confidential cloud devices.

What is Caliptra

Why Consistency is Important

Confidential device measurements are tenant visible

Interoperability, components intercommunicate and report to measurement

Functional consistency across operational flows, tightly coupled to life-cycle and live-site

Heterogeneity of RoT implementations is massive drain on our: operations; customer experience

Tenant Experience

Transparency on what enters and leaves, not explicitly what's inside.

Caliptra, focuses on monitoring ingestion points

Lower silicon burden of proof through transparency of RoT, narrows verification and audit.

Caliptra akin to a door that records entry into a room, don’t care about décor, just security at entry and exit

Transparency builds trust… provides assurance of the hardware mechanics for measurement

Root-of-Trust is a foundational hardware security primitive that bootstraps higher-level security capabilities

Why Transparency is important

Caliptra – HW View

• Open-source VeeR core, Instruction RAM (ICCM) & Data RAM (DCCM) physical separation, No DMA access from any peripherals/external SOC into ICCM/DCCM, No writes into ICCM on ROM-exit
• Side-channel protected Crypto HW & No FW access to security keys/assets (more on this later)

• Caliptra as-a-whole is an APB-device (can only speak when spoken to!)
• Cannot initiate random transactions to rest of the SOC
• No integrated peripherals required (coming in Gen2!)

Caliptra – Cryptos & Operations

• DICE (Device Identity Composite Engine) is implemented in HW
• Fuses are external but security critical fuses itself are decrypted with Caliptra internal class keys (by HW)
• Cryptos: ECC384, HMAC-DRBG, SHA256, SHA384/SHA512, HMAC-384, Integ-TRNG, DICE-obfuscation-Engine (DOE)
• Refer to Caliptra spec on the RFC references and side channel mitigation information.
• Key Vault & PCR Vault are implemented in HW
• FW (ROM or run-time) cannot access keys; only key-handles are available
• PCRs can only be ‘extended’
• Key vault also implements various key protection mechanisms (ex: a key can only be used for ‘ECC signing’)
• PCR signing is also fully implemented in HW (FW can only ‘request’ for PCR signing – cannot specify the key or change PCRs that are being signed)
• Assets are cleared and Cryptos are zeroized in debug/scan modes

Key Vault

PCR Vault

Cryptos

Caliptra - Status

Caliptra was open sourced on October 18^th, 2022 with multiple partners planning products. 

Microsoft, Google, AMD, Nvidia are founding project partners.

Built supporting industry standards; TCG DICE, DMTF SPDM, OCP Secure-boot, Attestation, Recovery.  

Design (RTL & ROM) release v1.0 on January 18, 2024. Run-time FW released March 11, 2024.

Project Caliptra Next Steps

Development & Discussions in the open – no more NDA requirements (CLA is still required)

CHIPSALLIANACE Caliptra Public WG meeting – Every Friday 9am PST

• Best technologies blossom with “brain share” & collaboration
• Security is the critical pillar to protect all “our” data and RoT technologies is the “Caliptra” of it

Call for Action

Acronyms