Method and system for key management in voice over internet protocol

• US 7,730,309 B2
• Filed: 07/27/2006
• Issued: 06/01/2010
• Est. Priority Date: 07/27/2005
• Status: Expired due to Fees

• Current Assignee: Philip R. Zimmermann
• Original Assignee: Philip R. Zimmermann
• Inventors: Zimmermann, Philip R.
• Primary Examiner(s): NGUYEN, MINH DIEU T
• Application Number:
  US11/460,621
• Publication Number:
  US 20070157026A1
• Time in Patent Office: 1,405 Days
• Field of Search: 713/171, 380/277, 380/283, 455/411
• US Class Current: 713/171
• CPC Class Codes: H04L 63/061 for key exchange, e.g. in peer-to-peer networks cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838
• CPC Class Codes: H04L 63/0861 using biometrical features, e.g. fingerprint, retina-scan cryptographic mechanisms or cryptographic arrangements for entity authentication using biological data H04L9/3231
• CPC Class Codes: H04L 63/126 the source of the received data
• CPC Class Codes: H04L 63/14 for detecting or protecting against malicious traffic
• CPC Class Codes: H04L 63/1466 Active attacks involving interception, injection, modification, spoofing of data unit addresses, e.g. hijacking, packet injection or TCP sequence number attacks
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/65 Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
• CPC Class Codes: H04L 9/0844 with user authentication or key authentication, e.g. ElGamal, MTI, MQV-Menezes-Qu-Vanstone protocol or Diffie-Hellman protocols using implicitly-certified keys
• CPC Class Codes: H04M 3/16 with lock-out or secrecy provision in party-line systems
• CPC Class Codes: 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
• CPC Class Codes: H04M 7/0078 Security; Fraud detection; Fraud prevention

Abstract

A method and system for a secure telephone protocol are disclosed, which can be implemented using current Voice over IP (VoIP) protocols, Session Initiation Protocol (SIP, as specified in the Request for Comment (RFC) 3261 from the Internet Engineering Task Force (IETF)), Real Time Transport Protocol (RTP, as specified in RFC 3550), and Secure RTP (SRTP, as specified in RFC 3711). The secure telephone protocol can include a shared secret value that is cached and then re-used later to authenticate a long series of session keys to be used for numerous separate secure phone calls over a long period of time, thereby providing cryptographic key continuity without the need for voice authentication. In an embodiment, the secure telephone protocol can utilize the Diffie-Hellman key exchange during call setup, and AES for encrypting the voice stream.

Claims

1. A method, comprising:

negotiating in a media path a cryptographic key exchange between a first user and a second user to compute session keys for Secure Real Time Protocol (SRTP) Voice Over Internet Protocol (VOIP) media streams;

computing a Short Authentication String (SAS) from the cryptographic key exchange between the first user and the second user, wherein computing includes computing the SAS in such a manner as to constrain a Man-In-The-Middle attack to one guess;

displaying the SAS to the first user and the second user such that an SAS mismatch indicates existence of a Man-In-The-Middle attack;

caching cryptographic key material created by the first user and the second user in a first communication session;

invoking the cryptographic key material in a second communication session between the first user and the second user, thereby establishing key continuity; and

augmenting cryptographic key material in the second communication session between the first user and the second user with the cryptographic key material from the first communication session.

2. The method of claim 1 further comprising:

caching entropy from the first communication session between the first user and the second user; and

augmenting entropy for session key generation in the second communication session between the first user and the second user with entropy from the first communication session.

3. The method of claim 1 wherein negotiating is performed by a proxy positioned between a client device and a network.