# US 2020/0401674 A1 · Systems and methods for securely processing content

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- Number: US 2020/0401674 A1
- Document ID: US20200401674A1
- Status: Published application
- Kind: A1
- Application number: 16/444,401
- Filed: 2019-06-18
- Published: 2020-12-24
- Earliest claimed: 2019-06-18
- Assignees: Comcast Cable Communications, LLC
- Applicants: Comcast Cable Communications, LLC
- Inventors: Andrew Morrow
- Web page: https://patentgrep.com/patent/US20200401674A1

## CPC

- G06F 21/10: Protecting distributed programs or content, e.g. vending or licensing of copyrighted material (protection in video systems or pay television H04N7/16) {; Digital rights management [DRM]}
- H04L 9/0897: {involving additional devices, e.g. trusted platform module [TPM], smartcard or USB}
- G06F 21/53: by executing in a restricted environment, e.g. sandbox or secure virtual machine
- G06F 21/57: Certifying or maintaining trusted computer platforms, e.g. secure boots or power-downs, version controls, system software checks, secure updates or assessing vulnerabilities
- H04L 9/083: {involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]}
- H04L 9/085: {Secret sharing or secret splitting, e.g. threshold schemes}
- H04L 9/3234: {involving additional secure or trusted devices, e.g. TPM, smartcard, USB or software token (network architectures or network communication protocols for supporting authentication of entities using an additional device in a packet data network H04L63/0853)}
- H04L 9/3247: {involving digital signatures}
- H04L 9/3268: {using certificate validation, registration, distribution or revocation, e.g. certificate revocation list [CRL]}
- G06F 21/107: {License processing; Key processing}
- H04L 2209/603: Digital right managament [DRM]
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A device may not trust another device with which it is in communication. To establish trust, a first device may send a second device an indication of signed code that is stored in a protected memory of the first device. Based on determining that the first device is a trusted device, the second device may send the first device an encrypted content asset, a decryption key associated with the content asset, and/or an encryption key associated with the content asset.

## Claims

### Claim 1

A method comprising:
receiving, by a key server and from a network device that is untrusted by the key server, an indication of code associated with a secure enclave, on the network device, that comprises a signed code module in a protected memory of the network device;
determining, based on the indication of the code, that the network device is a trusted device;
sending, based on determining that the network device is a trusted device and to the network device, a shared secret key;
receiving, from the network device, an encrypted request for a digital rights management (DRM) key associated with a content asset, wherein the encrypted request is encrypted using the shared secret key; and
sending, based on the encrypted request and to the network device, the DRM key and a decryption key.

### Claim 2 (depends on 1)

The method of claim 1, wherein the encrypted request further comprises a digital certificate associated with the network device; and
wherein the method further comprises storing an indication of the digital certificate in a database of trusted devices.

### Claim 3 (depends on 1)

The method of claim 1, wherein the determining that the network device is a trusted device comprises sending the indication of the code to an authentication device, wherein the authentication device is configured to determine, based on the indication of the code, that the secure enclave comprises a secure environment.

### Claim 4 (depends on 1)

The method of claim 1, wherein the sending the shared secret key comprises initiating a handshake protocol with the network device.

### Claim 5 (depends on 1)

The method of claim 1, wherein the DRM key is associated with a user device; and
wherein the request for the DRM key comprises an indication of the user device.

### Claim 6 (depends on 1)

The method of claim 1, wherein the indication of the code comprises an indication of an initial state of the signed code module.

### Claim 7 (depends on 1)

The method of claim 1, wherein the indication of the code associated with the secure enclave is associated with the key server.

### Claim 8

A system comprising:
a key server configured to:
receive, from a network device that is untrusted by the key server, an indication of code associated with a secure enclave, on the network device, that comprises a signed code module in a protected memory of the network device; and
send, based on receiving the indication of the code and to the network device, a shared secret key; and
the network device configured to:
send, to the key server, a request for a digital rights management (DRM) key associated with a content asset, wherein the request is encrypted using the shared secret key;
receive, from the key server and based on the request, an encrypted response that comprises the DRM key;
decrypt, using the secure enclave and the shared secret key, the encrypted response to determine the DRM key; and
decrypt, using the secure enclave and the DRM key, the content asset.

### Claim 9 (depends on 8)

The system of claim 8, wherein the key server comprises a device associated with at least one of a distributor of the content asset or a creator of the content asset.

### Claim 10 (depends on 8)

The system of claim 8, wherein the key server is configured to:
determine, based on receiving the indication of the code, that the network device is a trusted device; and
send the shared secret key based on determining that the network device is a trusted device.

### Claim 11 (depends on 8)

The system of claim 8, wherein the network device is configured to:
store the content asset in an unprivileged memory on the network device; and
transfer a portion of the content asset to the secure enclave.

### Claim 12 (depends on 11)

The system of claim 11, wherein the network device is configured to encrypt the content asset using the secure enclave and the DRM key.

### Claim 13 (depends on 8)

The system of claim 8, wherein the network device is configured to store the shared secret key in the secure enclave.

### Claim 14

A method comprising:
sending, to a key server and by a network device that is untrusted by the key server, an indication of code associated with a secure enclave, on the network device, that comprises a signed code module in a protected memory of the network device;
receiving, in response to sending the indication of the code and from the key server, a shared secret key;
sending, to the key server, a request for a digital rights management (DRM) key associated with a content asset, wherein the request is encrypted using the shared secret key;
receiving, from the key server, an encrypted response to the request, wherein the encrypted response comprises the DRM key and a decryption key;
determining, based on decrypting, using the secure enclave and the shared secret key, the encrypted response, the DRM key and the decryption key; and
decrypting, using the secure enclave and the decryption key, the content asset.

### Claim 15 (depends on 14)

The method of claim 14, further comprising encrypting the content asset using the secure enclave and the DRM key.

### Claim 16 (depends on 15)

The method of claim 15, further comprising sending the encrypted content asset to a user device.

### Claim 17 (depends on 15)

The method of claim 15, wherein the decrypting the content asset comprises:
storing a first portion of the content asset in the secure enclave; and
decrypting, using the decryption key, the first portion of the content asset.

### Claim 18 (depends on 17)

The method of claim 17, further comprising:
encrypting, using the DRM key, the first portion of the content asset; and,
sending, to a user device, the encrypted first portion of the content asset.

### Claim 19 (depends on 17)

The method of claim 17, wherein the decrypting the content asset further comprises:
sending or storing the first portion external to the secure enclave; storing a second portion of the content asset in the secure enclave; and
decrypting the second portion of the content asset.

### Claim 20 (depends on 14)

The method of claim 14, wherein the method further comprises:
modifying the content asset; and
encrypting the modified content asset.