- From: Joseph M. Reagle Jr. <reagle@w3.org>
- Date: Mon, 26 Feb 2001 17:39:09 -0500
- To: Takeshi Imamura <imamu@jp.ibm.com>, Hiroshi Maruyama <maruyama@jp.ibm.com>
- Cc: xml-encryption@w3.org
At 14:27 2/26/2001 +0900, Takeshi Imamura wrote: >We post a note on the "decryption transform" described in [1]. Hiroshi >Maruyama plans to talk about this note at the upcoming meeting. We look >forward to comments and discussions at the meeting and on this mailing >list. Takeshi and Hiroshi, Thank you for the very well specified proposal! In section 5 you write: >5 Security Considerations >It should be noted that in XML Signature [XML-Signature], the digest value >of a signed resource appears in clear text in a Reference element, even >though the resource itself is encrypted after signing. As noted by Hal >Finney in [Finney], this may become vulnerability by plain-text-guessing >attacks. Applications should implement appropriate means to protect from >these attacks. We discussed the options of encrypting the Signature, SignedInfo, or just the DigestValues. By "appropriate means" do you mean to state that in some cases there "may" not be a vulnerability, that concern over this vulnerability is completely within the applications domain, and/or we should leave which bits of the Signature are encrypted up to the application as well? Also, we should still identify the problem that this may be difficult in the following two situations: (a) where the signature and encryption are detached and not very well known by each other and (b) "Alice Encrypts element A and the Signature over the parent of A. Bob encrypts element B (sibling of A) but *not* the Signature since he doesn't know about it. Alice then decrypts A and it's Signature, providing information to a subsequent plain text attack." [1] Right? [1] http://lists.w3.org/Archives/Public/xml-encryption/2001Jan/0100.html __ Joseph Reagle Jr. http://www.w3.org/People/Reagle/ W3C Policy Analyst mailto:reagle@w3.org IETF/W3C XML-Signature Co-Chair http://www.w3.org/Signature W3C XML Encryption Chair http://www.w3.org/Encryption/2001/
Received on Monday, 26 February 2001 17:39:22 UTC