All,
Based on Russ Housley's message and the minimal value added by
signedAndEnvelopedData, I re-submit my proposal as follows:
When the new S/MIME v3 Message Specification is written, I propose that
Section 2.4 should be replaced by the following: "The PKCS #7 v1.5
specification defines six distinct content types: "data", "signedData",
"envelopedData", "signedAndEnvelopedData", "digestedData", and
"encryptedData". The "signedAndEnvelopedData" content type is not supported
as part of the S/MIME 3 set of specifications. Sending agents MUST NOT send
the "signedAndEnvelopedData" content type, but may they may send any of the
other content types depending on the services that the agent supports.
Receiving agents MUST support the "data", "signedData" and "envelopedData"
content types. Receiving agents are not required to support the
"signedAndEnvelopedData" content type."
Does anybody disagree with this proposal to eliminate support for the
"signedAndEnvelopedData" content type?
================================
John Pawling
jsp(_at_)jgvandyke(_dot_)com
J.G. Van Dyke & Associates, Inc.
================================
At 02:24 PM 10/14/97 -0400, Russ Housley wrote:
signedandEnvelopedData has a flaw. An attacker can stip the signature from
the message, then by changing the OID, the recipient will think that the
message we encrypted.
This attack is mitigated by using signedData and envelopedData independently.
Russ