Device using secure processing zone to establish trust for digital rights management
A DRM client on a device establishes trust with a DRM server for playback of digital content. The client executes in a secure execution environment, and the process includes (1) securely loading loader code from secure programmable memory and verifying it using a digital signature scheme and first key securely stored in the device; (2) by the verified loader code, loading DRM client code from the memory and verifying it using a digital signature scheme and second key included in the loader code; (3) by the verified DRM client code (a) obtaining a domain key from the memory; (b) encrypting the domain key with a device identifier using a DRM system key included in the DRM client code; and (c) sending the encrypted domain key and device identifier to the DRM server, whereby the device becomes registered to receive content licenses via secure communications encrypted using the domain key.
1. A method by which a signed client certificate is created for use by a client device in establishing mutually authenticated secure communications with a backend server of an application service, the communications to be secured by a client private/public key pair, the backend server storing a validation server public key used by the backend server to confirm a certificate signature of the signed client certificate, comprising:
at the client device, generating a first message and sending it to a device validation server, the generating including (1) generating the client private/public key pair using a random number generator, (2) generating a certificate signing request including the client public key and a certificate hash value; (3) encrypting the certificate signing request together with a device-specific authentication token and a locator value for the backend server, the encrypting producing encrypted values and performed using a domain token shared among a plurality of client devices, and (4) forming the first message to include the encrypted values and a hash of the domain token;
at the device validation server, (1) receiving the first message and confirming the hash of the domain token, (2) decrypting the encrypted values using the domain token to obtain decrypted values including the certificate signing request, the device-specific authentication token and the locator value, (3) generating the certificate signature from the decrypted values using a digital signature process and a validation server private key, and (4) securely sending the certificate signature to the client device; and
at the client device, forming the signed client certificate including the client public key and the certificate signature received from the device validation server.