Securing media stream communications

1 . A method performed by a processor of a user equipment (UE) for securing media stream communications involving an Internet Protocol Multimedia Subsystem (IMS) media communication link and a non-IMS media communication link, comprising:

establishing, between the UE and a second UE, the IMS media communication link and the non-IMS media communication link, wherein the IMS media communication link uses a previously established shared key;

determining that the previously established shared key cannot be used to protect communications between the UE and the second UE via the non-IMS media communication link;

establishing, in response to the determination, a shared key directly between the UE and the second UE via the IMS media communication link based on applying a first Session Initiation Protocol (SIP) value at the UE and applying a second SIP value at the second UE, wherein the first SIP value and the second SIP value are known to the UE and the second UE;

encrypting, using the shared key, first communications between the UE and the second UE via the non-IMS media communication link as encrypted communications; and

sending the encrypted communications between the UE and the second UE via the non-IMS media communication link.

2 . The method of claim 1 , wherein the IMS media communication link includes a cellular communication link and wherein the non-IMS media communication link includes a Wi-Fi communication link.

3 . The method of claim 1 , wherein the UE and the second UE verify the shared key using independently generated hash values exchanged via the IMS media communication link.

4 . The method of claim 1 , wherein encrypting, using the shared key first communications between the UE and the second UE via the non-IMS media communication link comprises:

using the shared key as a master key to generate one or more encryption keys; and

using the generated one or more encryption keys to protect communications between the UE and the second UE via the non-IMS media communication link.

5 . The method of claim 1 , further comprising:

determining an additional previously established shared key can be used to protect communications between the UE and a third UE via an additional non-IMS media communication link; and

using the previously established shared key to protect communications between the UE and the third UE via the additional non-IMS media communication link in response to determining that the additional previously established shared key can be used to protect the communications between the UE and the third UE via the additional non-IMS media communication link.

6 . The method of claim 1 , further comprising sending a hash verification message between the UE and the second UE via the IMS media communication link, wherein the hash verification message is configured to enable the second UE to verify the shared key.

7 . The method of claim 1 , further comprising:

generating, at the first UE, a first hash value of the shared key and generating, at the second UE, a second hash value of the shared key;

transmitting the first hash value via the IMS media communication link from the first UE to the second UE; and

verifying, at the second UE, the first hash value against the second hash value.

8 . A user equipment (UE), comprising:

a memory; and

a processor coupled to the memory, wherein the processor is configured with processor-executable instructions to:

establishing, between the UE and a second UE, an Internet Protocol Multimedia Subsystem (IMS) media communication link and a non-IMS media communication link, wherein the IMS media communication link uses a previously established shared key;

determine that the previously established shared key cannot be used to protect communications between the UE and the second UE via a non-IMS media communication link;

establish, in response to the determination, a shared key directly between the UE and the second UE via the IMS media communication link based on applying a first Session Initiation Protocol (SIP) value at the UE and applying a second SIP value at the second UE, wherein the first SIP value and the second SIP value are known to the UE and the second UE;

encrypt, using the shared key, first communications between the UE and the second UE via a non-IMS media communication link as encrypted communications; and

send the encrypted communications between the UE and the second UE via the non-IMS media communication link.

9 . The UE of claim 8 , wherein the IMS media communication link includes a cellular communication link and wherein the non-IMS media communication link includes a Wi-Fi communication link.

10 . The UE of claim 8 , wherein the UE and the second UE verify the shared key using independently generated hash values exchanged via the IMS media communication link.

11 . The UE of claim 8 , wherein the processor is further configured with processor-executable instructions to use the shared key to protect communications between the UE and the second UE via the non-IMS media communication link by:

using the shared key as a master key to generate one or more encryption keys; and

using the generated one or more encryption keys to protect communications between the UE and the second UE via the non-IMS media communication link.

12 . The UE of claim 8 , wherein the processor is further configured with processor-executable instructions to establish a shared key between the UE and the second UE via the IMS media communication link by:

determining an additional a previously established shared key can be used to protect the communications between the UE and a third UE via an additional non-IMS media communication link; and

using the previously established shared key to protect communications between the UE and the third UE via the additional non-IMS media communication link in response to determining that the additional previously established shared key can be used to protect the communications between the UE and the third UE via the additional non-IMS media communication link.

13 . The UE of claim 8 , wherein the processor is further configured with processor-executable instructions to send a hash verification message between the UE and the second UE via the IMS media communication link, wherein the hash verification message is configured to enable the second UE to verify the shared key.

14 . A non-transitory processor-readable medium having stored thereon processor-executable instructions configured to cause a processing device in a user equipment (UE) to perform operations comprising:

establishing, between the UE and a second UE, a IMS media communication link and a non-IMS media communication link, wherein the IMS media communication link uses a previously established shared key;

determining that the previously established shared key cannot be used to protect communications between the UE and a second UE via a non-IMS media communication link;

establishing, in response to the determination, a shared key directly between the UE and the second UE via an IMS media communication link based on applying a first Session Initiation Protocol (SIP) value at the UE and applying a second SIP value at the second UE, wherein the first SIP value and the second SIP value are known to the UE and the second UE;

encrypting, using the shared key, first communications between the UE and the second UE via a media communication link as encrypted communications; and

sending the encrypted communications between the UE and the second UE via the non-IMS media communication link.

15 . The non-transitory processor-readable medium of claim 14 , wherein the stored processor-executable instructions are further configured such that the IMS media communication link includes a cellular communication link and wherein the stored processor-executable instructions are further configured such that the non-IMS media communication link includes a Wi-Fi communication link.

16 . The non-transitory processor-readable medium of claim 14 , wherein the UE and the second UE verify the shared key using independently generated hash values exchanged via the IMS media communication link.

17 . The non-transitory processor-readable medium of claim 14 , wherein the stored processor-executable instructions are further configured such that encrypting, using the shared key, first communications between the UE and the second UE via the non-IMS media communication link comprises:

using the shared key as a master key to generate one or more encryption keys; and

using the generated one or more encryption keys to protect communications between the UE and the second UE via the non-IMS media communication link.

18 . The non-transitory processor-readable medium of claim 14 , wherein the stored processor-executable instructions are further configured such that establishing a shared key between the UE and the second UE via the IMS media communication link comprises:

determining an additional previously established shared key can be used to protect the communications between the UE and a third UE via an additional non-IMS media communication link; and

using the previously established shared key to protect communications between the UE and the third UE via the additional non-IMS media communication link in response to determining that the additional previously established shared key can be used to protect the communications between the UE and the third UE via the additional non-IMS media communication link.