# US 10,122,767 B2 · Systems and methods for conducting secure VOIP multi-party calls

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- Number: US 10,122,767 B2
- Document ID: US10122767B2
- Status: Granted
- Kind: B2
- Application number: 14/726,108
- Filed: 2015-05-29
- Published: 2016-12-01
- Granted: 2018-11-06
- Earliest claimed: 2015-05-29
- Assignees: Nagravision S.A.
- Applicants: Nagravision S.A.
- Inventors: Francois Fer; Marco Macchetti; Laurent Gauteron; Jerome Perrine
- Web page: https://patentgrep.com/patent/US10122767B2

## CPC

- H04L 65/1104: Session initiation protocol [SIP]
- G06F 16/22: Indexing; Data structures therefor; Storage structures
- H04L 63/06: {for supporting key management in a packet data network (cryptographic mechanisms or cryptographic arrangements for key management H04L9/08)}
- H04L 63/065: {for group communications (cryptographic mechanisms or cryptographic arrangements for key management involving conference or group key H04L9/0833)}
- H04L 65/403: Arrangements for multi-party communication, e.g. for conferences (data switching systems for conference H04L12/18; arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities H04M3/56; television conferencing systems H04N7/15)
- H04L 65/765: {intermediate}
- H04M 7/006: {Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer (H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42)}
- H04W 12/04: Key management, e.g. using generic bootstrapping architecture [GBA]
- H04W 12/08: Access security
- H04W 12/61: Time-dependent
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

System and method for establish secure conference calls. In one example system, a central conference call server establishes point-to-point connections with accessory devices comprising a secure element and connected to corresponding participant devices. The conference call server includes an interface to a plurality of secure elements configured to perform scrambling and unscrambling of media signals communicated to and from the accessory devices. In another example, one of the participant devices operates as the central conference call server. In other examples, participant devices communicate on a conference call via point-to-point connections between all accessory devices connected to the participant devices. The accessory devices include secure elements for decryption and encryption of media signals communicated between the accessory devices.

## Claims

### Claim 1

A method comprising:
communicating, via a communication interface of a conference-call server, during a conference-call session, a plurality of data packets over a data network with a plurality of remote endpoints of the conference-call session, each data packet comprising a packet head and an encrypted packet payload comprising encrypted audio;
receiving, via the communication interface during the conference-call session, at a cryptographic interface of the conference-call server coupled to the communication interface, the respective data packets sent from the respective remote endpoints, the cryptographic interface relaying the respective data packets to respective server-side hardware elements of a plurality of server-side secure hardware elements, the cryptographic interface comprising a plurality of individual physical-connection ports, each of the individual physical-connection ports configured to connect to the respective server-side secure hardware elements;
each of the server-side secure hardware elements of the conference-call server establishing a respective cryptographic relationship with a different respective remote endpoint of the conference-call session at least in part by negotiating respective cryptographic key information with its respective remote endpoint, each such cryptographic relationship having its own security parameters that (i) include the cryptographic key information and (ii) are inaccessible to the communication interface;
each server-side secure hardware element decrypting the encrypted packet payload of the respective relayed data packet using its respective security parameters;
an audio mixer receiving the respective decrypted audio of the respective decrypted packet payload from the respective server-side secure hardware elements, mixing the respective decrypted audio, and providing unencrypted mixed audio back to each of the plurality of server-side secure elements;
each server-side secure hardware element encrypting the unencrypted mixed audio using its respective security parameters; and parameters and
the cryptographic interface outputting the respective encrypted mixed audio to the communication interface for transmission via the communication interface to the respective remote endpoint.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
receiving, at the conference-call server, a respective initiation request to initiate a respective secure communication connection from each remote endpoint of the plurality of remote endpoints,
wherein, in response to receiving the respective initiation requests, the respective cryptographic relationships are established at least in part by relaying key information from the respective remote endpoints to the corresponding server-side secure hardware elements.

### Claim 3 (depends on 2)

The method of claim 2, wherein establishing the respective corresponding cryptographic relationships comprises each server-side secure hardware element performing a key-exchange to generate a respective server decryption key to decrypt the respective encrypted audio from the respective remote endpoint and a respective server encryption key to encrypt the mixed audio.

### Claim 4 (depends on 3)

The method of claim 3, wherein the respective key-exchanges comprise Diffie-Hellman key-exchanges.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
receiving, at the conference-call server, a global key from each remote endpoint of the plurality of remote endpoints; and
authenticating, at the conference-call server, the global key at least in part by determining whether the global key is valid for use to participate in the conference-call session.

### Claim 6 (depends on 5)

The method of claim 5, wherein authenticating the global key further comprises determining whether the global key is valid for a time and day on which the request is received.

### Claim 7 (depends on 5)

The method of claim 5, further comprising:
receiving, at the conference-call server, a request for the global key from one of the remote endpoints for participation in the conference-call session;
the conference-call server retrieving the global key from a key-management database; and
sending the global key from the conference-call server to the requesting remote endpoint.

### Claim 8 (depends on 1)

The method of claim 1, further comprising:
receiving, at the conference-call server, a segment key indicative of a group to which a user of the corresponding remote endpoint belongs; and
authenticating, at the conference-call server, the corresponding segment key by determining whether the corresponding segment key is valid for use to participate in the conference-call session.

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
receiving, at the conference-call server, a segment-key request for a segment key from one of the remote endpoints corresponding to a group to which a user of at least one other remote endpoint belongs;
the conference-call server retrieving the segment key from a key-management database; and
the conference-call server sending the segment key to the requesting remote endpoint.

### Claim 10

A conference-call server comprising:
a communication interface configured to communicate, during a conference-call session, a plurality of data packets over a data network with a plurality of remote endpoints of the conference-call session, each data packet comprising a packet header and an encrypted packet payload comprising encrypted audio;
a cryptographic interface coupled to the communication interface, the cryptographic interface comprising a plurality of individual physical-connection ports, each of the individual physical-connection ports configured to connect to a respective server-side secure hardware element of a plurality of server-side secure hardware elements, the cryptographic interface configured to receive, via the communication interface during the conference-call session, the respective data packets sent from the respective remote endpoints and to relay the respective data packets to the respective server-side secure hardware elements;
each server-side secure hardware element configured to:
establish a respective cryptographic relationship with a different respective remote endpoint of the plurality of remote endpoints of the conference-call session at least in part by negotiating respective cryptographic key information with its respective remote endpoint, each such cryptographic relationship having its own security parameters that (i) include the cryptographic key information and (ii) are inaccessible to the communication interface; and
decrypt the encrypted packet payload of the respective relayed data packet using its respective security parameters;
an audio mixer configured to receive the respective decrypted audio of the respective decrypted packet payload from the respective server-side secure hardware elements, to mix the respective decrypted audio, and to provide unencrypted mixed audio back to each of the plurality of server-side secure hardware elements,
wherein each server-side secure hardware element is further configured to encrypt the unencrypted mixed audio using its respective security parameters,
wherein the cryptographic interface is further configured to output the respective encrypted mixed audio from the respective server-side secure hardware elements to the communication interface for transmission via the communication interface to the respective remote endpoint.

### Claim 11 (depends on 10)

The conference-call server of claim 10, wherein the respective server-side secure hardware elements comprise respective microSD cards.

### Claim 12 (depends on 10)

The conference-call server of claim 10, wherein the cryptographic interface is a hardware interface to the plurality of server-side secure hardware elements selected from the group consisting of: a smart card interface, a ball grid array (“BGA”) interface, a surface mount device (“SMD”) interface, and a printed circuit board (“PCB”) interface.

### Claim 13 (depends on 10)

The conference-call server of claim 10, wherein the cryptographic key information of each server-side secure hardware element comprise a server encryption key and a server decryption key, each respective key being generated using a key-exchange performed during establishment of the respective cryptographic relationship using key information received from the respective remote endpoint, wherein the server decryption key is used to decrypt the respective encrypted audio from the respective remote endpoint and the server encryption key is used to encrypt the mixed audio.

### Claim 14 (depends on 13)

The conference-call server of claim 13, wherein the respective key-exchanges comprise Diffie-Hellman key-exchanges.

### Claim 15 (depends on 10)

The conference-call server of claim 10, further comprising a remote-endpoint-authentication module configured to authenticate a global key provided by a given remote endpoint of the plurality of remote endpoints during initiation of its respective secure media session with the conference-call server.

### Claim 16 (depends on 15)

The conference-call server of claim 15, wherein the remote-endpoint-authentication module is further configured to validate a date and time associated with the global key.

### Claim 17 (depends on 15)

The conference-call server of claim 15, wherein the remote-endpoint-authentication module is further configured to validate a segment key provided by a given remote endpoint in the plurality of remote endpoints during initiation of the corresponding secure media session with the conference-call server, the segment key being indicative of a group identity of a user of the given remote endpoint.

### Claim 18 (depends on 15)

The conference-call server of claim 15, further comprising a key-management database configured to maintain the global key and to provide the global key to requesting remote endpoints during respective registration processes.

### Claim 19 (depends on 18)

The conference-call server of claim 18, wherein the key-management database is further configured to:
maintain a segment key having a value indicative of a group identity; and
provide the segment key to at least one of the remote endpoints during its respective registration process.