Key reuse in Secure MIME for the Session Initiation Protocol(SIP)

Document Type Expired Internet-Draft (individual)
Authors Shinya Tachimoto  , Kumiko Ono 
Last updated 2005-07-20
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


The SIP User Agent uses Secure MIME (S/MIME) Cryptographic Message Syntax (CMS) EnvelopedData to protect SIP messages for confidentiality. While SIP messages can be encrypted with different keying materials for each message in a dialog, it usually requires a public key operation for each message and the computational cost of such operations are relatively expensive. This draft proposes a method of bidirectional key exchange to reuse keying materials for S/MIME-secured messages in a dialog and use a symmetric key mechanism instead of an asymmetric key mechanism such as a public key operation. The proposed mechanism also achieves the sharing of keying material among multiple entities simply.


Shinya Tachimoto (
Kumiko Ono (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)