Encrypted and authenticated firmware provisioning with root-of-trust based security

A method for authenticating firmware for an electronic device, the electronic device comprising a security module having a physical unclonable function (PUF), the security module configured to establish a firmware key pair (FPK, FSK) based on a first challenge and response to the PUF and an enrolment key pair (EPK, ESK) based on a second challenge and response to the PUF, wherein the firmware key pair comprises a firmware public key (FPK) and a firmware secret key (FSK), and wherein the enrolment key pair (EPK, ESK) comprises an enrolment public key (EPK) and an enrolment secret key (ESK), the method comprising:

• receiving, from a server, a hash of firmware over a secure communication channel, the firmware for installation on the electronic device;
• signing the hash of the firmware using a secret authority key of an authority key pair comprising a public authority key (PAK) and the secret authority key (SAK), wherein the public authority key is embedded securely in the electronic device;
• initiating communication of the signature over the hash to a third party for installation on the electronic device;
• and
• sending, over a secure communication channel to the server, the FPK and an associated device identifier for identifying the electronic device, the device identifier comprising a function of the EPK.

A method for performance by an electronic device, the electronic device comprising a security module having a physical unclonable function (PUF), the security module configured to establish a firmware key pair (FPK, FSK) based on a first challenge and response to the PUF, the firmware key pair comprising a firmware public key (FPK) and a firmware secret key (FSK), wherein the method comprises:

• using the FSK, decrypting an encrypted server decryption key, wherein the server decryption key is encrypted using the FPK;
• using the decrypted server decryption key, decrypting firmware and a signature over a hash of the firmware;
• verifying, using a public authority key embedded securely in the electronic device, that the hash of the firmware has been signed by a trusted authority;
• and
• based on the verifying, installing the decrypted firmware on the electronic device.

An electronic device comprising:

• a security module having a physical unclonable function (PUF), the security module configured to establish a firmware key pair (FPK, FSK) based on a first challenge and response to the PUF, the firmware key pair comprising a firmware public key (FPK) and a firmware secret key (FSK);
• one or more processors comprising or communicatively coupled to the security module, wherein the one or more processors are configured to:
• use the FSK to decrypt an encrypted server decryption key, wherein the server decryption key is encrypted using the FPK;
• use the decrypted server decryption key to decrypt firmware and a signature over a hash of the firmware;
• verify, using a public authority key embedded securely in the electronic device, that the hash of the firmware has been signed by a trusted authority;
• and
• based on the verifying, install the decrypted firmware on the electronic device.

A system for providing firmware to an electronic device, the electronic device comprising a security module having a physical unclonable function (PUF), the security module configured to establish a firmware key pair (FPK, FSK) based on a first challenge and response to the PUF, wherein the firmware key pair comprises a firmware public key (FPK) and a firmware secret key (FSK), the system comprising a trusted authority and a server,

• wherein the trusted authority is configured to:
• receive a hash of firmware from the server;
• sign the hash of the firmware using a secret authority key of an authority key pair comprising a public authority key and the secret authority key, wherein the public authority key is embedded securely in the electronic device;
• send the signature over the hash of the firmware to the server;
• and
• send the FPK to the server;
• and
• wherein the server is configured to:
• receive the signature from the trusted authority;
• receive the FPK from the trusted authority;
• encrypt the firmware and the signature using a server encryption key;
• encrypt a server decryption key using the FPK, the server decryption key for decrypting the encrypted firmware and the encrypted signature;
• communicating the encrypted firmware, the encrypted signature, and the encrypted server decryption key to a third party for installation on the electronic device.