--- 1/draft-ietf-dkim-ssp-04.txt 2008-08-06 00:12:21.000000000 +0200 +++ 2/draft-ietf-dkim-ssp-05.txt 2008-08-06 00:12:21.000000000 +0200 @@ -1,23 +1,23 @@ Network Working Group E. Allman Internet-Draft Sendmail, Inc. Intended status: Standards Track J. Fenton -Expires: January 3, 2009 Cisco Systems, Inc. +Expires: February 6, 2009 Cisco Systems, Inc. M. Delany Yahoo! Inc. J. Levine Taughannock Networks - July 2, 2008 + August 5, 2008 DKIM Author Domain Signing Practices (ADSP) - draft-ietf-dkim-ssp-04 + draft-ietf-dkim-ssp-05 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that @@ -28,78 +28,80 @@ and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on January 3, 2009. + This Internet-Draft will expire on February 6, 2009. Abstract DomainKeys Identified Mail (DKIM) defines a domain-level authentication framework for email to permit verification of the source and contents of messages. This document specifies an adjunct mechanism to aid in assessing messages that do not contain a DKIM signature for the domain used in the author's address. It defines a - record that can advertise whether they sign their outgoing mail, and - how other hosts can access those records. + record that can advertise whether a domain signs its outgoing mail, + and how other hosts can access that record. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Language and Terminology . . . . . . . . . . . . . . . . . . . 3 2.1. Terms Imported from DKIM Signatures Specification . . . . 3 2.2. Valid Signature . . . . . . . . . . . . . . . . . . . . . 4 2.3. Author Address . . . . . . . . . . . . . . . . . . . . . . 4 2.4. Author Domain . . . . . . . . . . . . . . . . . . . . . . 4 2.5. Alleged Author . . . . . . . . . . . . . . . . . . . . . . 4 2.6. Author Domain Signing Practices . . . . . . . . . . . . . 4 2.7. Author Signature . . . . . . . . . . . . . . . . . . . . . 4 3. Operation Overview . . . . . . . . . . . . . . . . . . . . . . 5 3.1. ADSP Applicability . . . . . . . . . . . . . . . . . . . . 5 3.2. ADSP Usage . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. ADSP Results . . . . . . . . . . . . . . . . . . . . . . . 6 4. Detailed Description . . . . . . . . . . . . . . . . . . . . . 6 4.1. DNS Representation . . . . . . . . . . . . . . . . . . . . 6 - 4.2. Publication of ADSP Records . . . . . . . . . . . . . . . 6 + 4.2. Publication of ADSP Records . . . . . . . . . . . . . . . 7 4.3. ADSP Lookup Procedure . . . . . . . . . . . . . . . . . . 7 - 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 - 5.1. ADSP Specification Tag Registry . . . . . . . . . . . . . 8 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 + 5.1. ADSP Specification Tag Registry . . . . . . . . . . . . . 9 5.2. ADSP Outbound Signing Practices Registry . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 - 6.1. ADSP Threat Model . . . . . . . . . . . . . . . . . . . . 9 + 6.1. ADSP Threat Model . . . . . . . . . . . . . . . . . . . . 10 6.2. DNS Attacks . . . . . . . . . . . . . . . . . . . . . . . 10 - 6.3. DNS Wildcards . . . . . . . . . . . . . . . . . . . . . . 10 + 6.3. DNS Wildcards . . . . . . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7.1. References - Normative . . . . . . . . . . . . . . . . . . 11 - 7.2. References - Informative . . . . . . . . . . . . . . . . . 11 - Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 11 + 7.2. References - Informative . . . . . . . . . . . . . . . . . 12 + Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 12 A.1. Single Location Domains . . . . . . . . . . . . . . . . . 12 - A.2. Bulk Mailing Domains . . . . . . . . . . . . . . . . . . . 12 + A.2. Bulk Mailing Domains . . . . . . . . . . . . . . . . . . . 13 A.3. Bulk Mailing Domains with Discardable Mail . . . . . . . . 13 A.4. Third Party Senders . . . . . . . . . . . . . . . . . . . 13 - A.5. Non-email Domains . . . . . . . . . . . . . . . . . . . . 13 - Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 13 - Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 13 - C.1. Changes since -ietf-dkim-03 . . . . . . . . . . . . . . . 14 - C.2. Changes since -ietf-dkim-02 . . . . . . . . . . . . . . . 14 - C.3. Changes since -ietf-dkim-ssp-01 . . . . . . . . . . . . . 15 - C.4. Changes since -ietf-dkim-ssp-00 . . . . . . . . . . . . . 16 - C.5. Changes since -allman-ssp-02 . . . . . . . . . . . . . . . 16 - C.6. Changes since -allman-ssp-01 . . . . . . . . . . . . . . . 17 - C.7. Changes since -allman-ssp-00 . . . . . . . . . . . . . . . 17 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 - Intellectual Property and Copyright Statements . . . . . . . . . . 19 + A.5. Domains with Independent Users and Liberal Use Policies . 14 + A.6. Non-email Domains . . . . . . . . . . . . . . . . . . . . 14 + Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 14 + Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 14 + C.1. Changes since -ietf-dkim-04 . . . . . . . . . . . . . . . 14 + C.2. Changes since -ietf-dkim-03 . . . . . . . . . . . . . . . 14 + C.3. Changes since -ietf-dkim-02 . . . . . . . . . . . . . . . 15 + C.4. Changes since -ietf-dkim-ssp-01 . . . . . . . . . . . . . 16 + C.5. Changes since -ietf-dkim-ssp-00 . . . . . . . . . . . . . 17 + C.6. Changes since -allman-ssp-02 . . . . . . . . . . . . . . . 17 + C.7. Changes since -allman-ssp-01 . . . . . . . . . . . . . . . 18 + C.8. Changes since -allman-ssp-00 . . . . . . . . . . . . . . . 18 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 + Intellectual Property and Copyright Statements . . . . . . . . . . 20 1. Introduction DomainKeys Identified Mail (DKIM) defines a mechanism by which email messages can be cryptographically signed, permitting a signing domain to claim responsibility for the introduction of a message into the mail stream. Message recipients can verify the signature by querying the signer's domain directly to retrieve the appropriate public key, and thereby confirm that the message was attested to by a party in possession of the private key for the signing domain. @@ -154,21 +156,21 @@ addresses, the message has multiple Author Addresses. 2.4. Author Domain An "Author Domain" is everything to the right of the "@" in an Author Address (excluding the "@" itself). 2.5. Alleged Author An "Alleged Author" is an Author Address of a message; it is - "alleged" because it has not yet been verified. + "alleged" because it has not yet been checked. 2.6. Author Domain Signing Practices "Author Domain Signing Practices" (or just "practices") consist of a machine-readable record published by the domain of an Alleged Author which includes statements about the domain's practices with respect to mail it sends with its domain in the From: line. 2.7. Author Signature @@ -202,29 +204,29 @@ independently on each address. This standard does not address the process a host might use to combine the lookup results. 3.1. ADSP Applicability ADSP as defined in this document is bound to DNS. For this reason, ADSP is applicable only to Author Domains with appropriate DNS records (see Note below). The handling of other Author Domains is outside the scope of this document. However, attackers may use such domain names in a deliberate attempt to sidestep an organization's - ADSP policy statements. It is up to the ADSP verifier implementation + ADSP policy statements. It is up to the ADSP checker implementation to return an appropriate error result for Author Domains outside the scope of ADSP. Note: The results from DNS queries that are intended to validate a domain name unavoidably approximate the set of Author Domains that can appear in legitimate email. For example, a DNS A record could belong to a device that does not even have an email - implementation. It is up to the verifier to decide what degree of + implementation. It is up to the checker to decide what degree of approximation is acceptable. 3.2. ADSP Usage Depending on the Author Domain(s) and the signatures in a message, a recipient gets varying amounts of useful information from each ADSP lookup. o If a message has no Valid Signature, the ADSP result is directly relevant to the message. @@ -271,116 +273,122 @@ delimiters between the strings. The ADSP record for a domain is published at a location in the domain's DNS hierarchy prefixed by _adsp._domainkey.; e.g., the ADSP record for example.com would be a TXT record that is published at "_adsp._domainkey.example.com". A domain MUST NOT publish more than one ADSP record; the semantics of an ADSP lookup that returns multiple ADSP records for a single domain are undefined. (Note that example.com and mail.example.com are different domains.) + ADSP records MUST NOT be published at any location other than + the_adsp._domainkey subdomain of the domain for which they are + expressing signing practices. In particular, domains MUST NOT + publish ADSP records with wildcard names. Wildcards within a domain + publishing ADSP records pose a particular problem, as discussed in + more detail in Section 6.3. + 4.2. Publication of ADSP Records ADSP is intended to apply to all mail sent using the domain name string of an Alleged Author. - Wildcards within a domain publishing ADSP records pose a particular - problem. This is discussed in more detail in Section 6.3. - 4.2.1. Record Syntax ADSP records use the "tag=value" syntax described in section 3.2 of - [RFC4871]. + [RFC4871]. Every ADSP record MUST start with an outbound signing + practices tag, so the first four characters of the record are lower + case "dkim". Tags used in ADSP records are described below. Unrecognized tags - MUST be ignored. In the ABNF below, the FWS token is imported from - [RFC4871]. The ALPHA and DIGIT tokens are imported from [RFC5234]. + MUST be ignored. In the ABNF below, the WSP token, and the ALPHA and + DIGIT tokens are imported from [RFC5234]. dkim= Outbound signing practices for the domain (plain-text; REQUIRED). Possible values are as follows: unknown The domain might sign some or all email. all All mail from the domain is signed with an Author Signature. discardable All mail from the domain is signed with an Author Signature. Furthermore, if a message arrives without a valid Author Signature due to modification in transit, submission via a path without access to a signing key, or other reason, the domain encourages the recipient(s) to discard it. ABNF: - adsp-dkim-tag = %x64.6b.69.6d *FWS "=" *FWS + adsp-dkim-tag = %x64.6b.69.6d *WSP "=" *WSP ("unknown" / "all" / "discardable") 4.3. ADSP Lookup Procedure Hosts doing an ADSP lookup MUST produce a result that is semantically equivalent to applying the following steps in the order listed below. In practice, these steps can be performed in parallel in order to improve performance. However, implementations SHOULD avoid doing unnecessary DNS lookups. For the purposes of this section a "valid ADSP record" is one that is both syntactically and semantically correct; in particular, it - matches the ABNF for a "tag-list" and includes a defined "dkim=" tag. + matches the ABNF for a "tag-list" and includes a valid "dkim" tag. - Verify Domain Scope: An ADSP verifier implementation MUST determine + Check Domain Scope: An ADSP checker implementation MUST determine whether a given Author Domain is within scope for ADSP. Given the - background in Section 3.1 the verifier MUST decide which degree of - over-approximation is acceptable. The verifier MUST return an + background in Section 3.1 the checker MUST decide which degree of + approximation is acceptable. The checker MUST return an appropriate error result for Author Domains that are outside the scope of ADSP. The host MUST perform a DNS query for a record corresponding to the Author Domain (with no prefix). The type of the query can be of any type, since this step is only to determine if the domain itself exists in DNS. This query MAY be done in parallel with the query to fetch the Named ADSP Record. If the result of this query is that the Author domain does not exist in the DNS (often called an "NXDOMAIN" error), the algorithm MUST terminate with an error indicating that the domain is out of scope. NON-NORMATIVE DISCUSSION: Any resource record type could be used for this query since the existence of a resource record of any type will prevent an "NXDOMAIN" error. MX is a reasonable choice for this purpose because this record type is thought to be the most common for domains used in e-mail, and will therefore produce a result which can be more readily cached than a negative result. - If the domain does exist, the verifier MAY make more extensive + If the domain does exist, the checker MAY make more extensive checks to verify the existence of the domain, such as the ones described in Section 5 of [RFC2821]. If those checks indicate that the Author domain does not exist for mail, e.g., the domain - has no MX, A, or AAAA record, the verifier SHOULD terminate with - an error indicating that the domain is out of scope. + has no MX, A, or AAAA record, the checker SHOULD terminate with an + error indicating that the domain is out of scope. Fetch Named ADSP Record: The host MUST query DNS for a TXT record corresponding to the Author Domain prefixed by "_adsp._domainkey." (note the trailing dot). If the result of this query is a "NOERROR" response with an answer which is a valid ADSP record, use that record, and the algorithm terminates. If a query results in a "SERVFAIL" error response, the algorithm terminates without returning a result; possible actions include queuing the message or returning an SMTP error indicating a temporary failure. 5. IANA Considerations ADSP adds the following namespaces to the IANA registry. In all cases, new values are assigned only for values that have been - documented in a published RFC that has IETF Consensus [RFC2434]. + documented in a published RFC that has IETF Consensus [RFC5226]. 5.1. ADSP Specification Tag Registry An ADSP record provides for a list of specification tags. IANA has established the ADSP Specification Tag Registry for specification tags that can be used in ADSP fields. The initial entry in the registry is: +------+-----------------+ | TYPE | REFERENCE | @@ -462,64 +470,73 @@ Because ADSP operates within the framework of the legacy e-mail system, the default result in the absence of an ADSP record is that the domain does not sign all of its messages. It is therefore important that the ADSP clients distinguish a DNS failure such as "SERVFAIL" from other DNS errors so that appropriate actions can be taken. 6.3. DNS Wildcards + DNS wildcards (described in [RFC4592]) that exist in the DNS + hierarchy at or above the domain being checked interfere with the + ability to verify the scope of the ADSP check described in + Section 4.3. For example, a wildcard record for *.example.com makes + all subdomains such as foo.example.com exist in the DNS. Domains + that intend to make active use of ADSP by publishing a practice other + than Unknown are advised to avoid the use of wildcards elsewhere in + their hierarchy. + If a domain contains wildcards, then any name that matches the - wildcard according to [RFC4592] is potentially a valid mail domain - eligible for ADSP. It is possible to add a wildcard TXT record - alongside a wildcard MX that will provide suitable ADSP records for - any domain chosen by an attacker, since if the wildcard synthesizes - chosen-name.example.com IN MX, it will then also synthesize - _adsp._domainkey.chosen-name.example.com IN TXT. However multiple - wildcard TXT records produce an undefined ADSP result, which means - you cannot also publish both ADSP records and records for any other - TXT-using protocol (such as SPF) for a wildcard domain. + wildcard can appear to be a valid mail domain eligible for ADSP. But + the "_adsp._domainkey." prefix on ADSP records does not allow + publication of wildcard records that cover ADSP records without also + covering non-ADSP records, nor of wildcard records that cover non- + ADSP records without also covering ADSP records. Hence a domain MUST + NOT publish wildcard ADSP records. 7. References 7.1. References - Normative [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. - [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an - IANA Considerations Section in RFCs", BCP 26, RFC 2434, - October 1998. - [RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April 2001. [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, March 2005. - [RFC4686] Fenton, J., "Analysis of Threats Motivating DomainKeys - Identified Mail (DKIM)", RFC 4686, September 2006. + [RFC4592] Lewis, E., "The Role of Wildcards in the Domain Name + System", RFC 4592, July 2006. [RFC4871] Allman, E., Callas, J., Delany, M., Libbey, M., Fenton, J., and M. Thomas, "DomainKeys Identified Mail (DKIM) Signatures", RFC 4871, May 2007. + [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an + IANA Considerations Section in RFCs", BCP 26, RFC 5226, + May 2008. + [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. 7.2. References - Informative [RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April 2001. + [RFC4686] Fenton, J., "Analysis of Threats Motivating DomainKeys + Identified Mail (DKIM)", RFC 4686, September 2006. + [RFC5016] Thomas, M., "Requirements for a DomainKeys Identified Mail (DKIM) Signing Practices Protocol", RFC 5016, October 2007. Appendix A. Usage Examples These examples are intended to illustrate typical uses of ADSP. They are not intended to be exhaustive, nor to apply to every domain's or mail system's individual situation. @@ -536,22 +553,23 @@ A common mail system configuration handles all of a domain's users' incoming and outgoing mail through a single MTA or group of MTAs. In that case, the MTA(s) can be configured to sign outgoing mail with an Author Signature. In this situation it might be appropriate to publish an ADSP record for the domain containing "all", depending on whether the users also send mail through other paths that do not apply an Author Signature. Such paths could include MTAs at hotels or hotspot networks used by - travelling users, or web sites that provide "mail an article" - features. + travelling users, web sites that provide "mail an article" features, + user messages sent through mailing lists, or third party mail clients + that support multiple user identities. A.2. Bulk Mailing Domains Another common configuration uses a domain solely for bulk or broadcast mail, with no individual human users, again typically sending all the mail through a single MTA or group of MTAs that can apply an Author Signature. In this case, the domain's management can be confident that all of its outgoing mail will be sent through the signing MTA. Lacking individual users, the domain is unlikely to participate in mailing lists, but could still send mail through other @@ -570,58 +588,82 @@ Regardless of the DNS and key management strategy chosen, whoever maintains the DKIM records for the domain could also install an ADSP record containing "all". A.3. Bulk Mailing Domains with Discardable Mail In some cases, a domain might sign all of its outgoing mail with an Author Signature, but prefer that recipient systems discard mail without a valid Author Signature to avoid confusion from mail sent - from sources that do not apply an Author Signature. (This latter - kind of mail is sometimes loosely called "forgeries".) In that case, - it might be appropriate to publish an ADSP record containing + from sources that do not apply an Author Signature. (In the case of + domains with tightly controlled outgoing mail, this latter kind of + mail is sometimes loosely called "forgeries".) In that case, it + might be appropriate to publish an ADSP record containing "discardable". Note that a domain SHOULD NOT publish a "discardable" record if it wishes to maximize the likelihood that mail from the domain is delivered, since it could cause some fraction of the mail the domain sends to be discarded. A.4. Third Party Senders Another common use case is for a third party to enter into an agreement whereby that third party will send bulk or other mail on behalf of a designated author or author domain, using that domain in the RFC2822 From: or other headers. Due to the many and varied complexities of such agreements, third party signing is not addressed in this specification. -A.5. Non-email Domains +A.5. Domains with Independent Users and Liberal Use Policies + + When a domain has independent users and its usage policy does not + explicitly restrict them to sending mail only from designated mail + servers (e.g. many ISP domains and even some corporate domains), then + it is only appropriate to publish an ADSP record containing + "unknown". Publishing either "all" or "discardable" will likely + result in significant breakage because independent users are likely + to send mail from the external paths enumerated in Appendix A.1. + +A.6. Non-email Domains If a domain sends no mail at all, it can safely publish a "discardable" ADSP record, since any mail with an author address in the domain is a forgery. Appendix B. Acknowledgements This document greatly benefited from comments by Steve Atkins, Jon Callas, Dave Crocker, JD Falk, Arvel Hathcock, Ellen Siegel, Michael Thomas, and Wietse Venema. Appendix C. Change Log *NOTE TO RFC EDITOR: This section may be removed upon publication of this document as an RFC.* -C.1. Changes since -ietf-dkim-03 +C.1. Changes since -ietf-dkim-04 - o Name change for title and filename, to be ADSP + o Require dkim at the front of each record. + o Disparage wildcard records. + + o Changed ABNF use of whitespace from FWS back to WSP, dkim-base is + wrong. + + o RFC 2434 -> 5226, make ref to 4686 informational since it's not + standards track. + + o Improve examples with material from Ellen. + +C.2. Changes since -ietf-dkim-03 + + o Name change for title and filename, to be ADSP o String changes throughout, to author Domain signing practices and to aDsp. o Added some keywords. o Clarified comparison of local part and domain in Author Address. o Streamlined the Abstract. o Revised text of last bullet in Results list. @@ -640,21 +682,21 @@ o Revised wildcard text. o Removed 't' tag. o Removed ADSP Flags Registry section. o Changed ABNF use of whitespace from WSP back to FWS, for consistency with dkim-base. -C.2. Changes since -ietf-dkim-02 +C.3. Changes since -ietf-dkim-02 o Merge in more text from ADSP draft. o Phrase actions as host's rather than checker. o Explanatory description of i= matching. o Lookup procedure consistently refers to one ADSP record per lookup. @@ -662,21 +704,21 @@ o Simplify imports of terms from other RFCs, add Local-part, 4234 -> 5234. o Add usage example appendix. o Add IANA considerations. o Update authors list -C.3. Changes since -ietf-dkim-ssp-01 +C.4. Changes since -ietf-dkim-ssp-01 o Reworded introduction for clarity. o Various definition clarifications. o Changed names of practices to unknown, all, and discardable. o Removed normative language mandating use of SSP in particular situations (issue 1538). @@ -710,21 +752,21 @@ o Introduced the concepts of "SSP Checker" and "Evaluator". o Multiple author case now handled my separate invocations of SSP checker by Evaluator (issue 1525). o Removed check to avoid querying top-level domains. o Changed ABNF use of whitespace from [FWS] to *WSP (partially addresses issue 1543). -C.4. Changes since -ietf-dkim-ssp-00 +C.5. Changes since -ietf-dkim-ssp-00 o Clarified Operation Overview and eliminated use of Legitimate as the counterpart of Suspicious since the words have different meanings. o Improved discussion (courtesy of Arvel Hathcock) of the use of TXT records in DNS vs. a new RR type. o Clarified publication rules for multilevel names. @@ -739,56 +781,56 @@ o Added "handling" tag to express alleged sending domain's preference about handling of Suspicious messages. o Clarified handling of SERVFAIL error in SSP check. o Replaced "entity" with "domain", since with the removal of user- granularity SSP, the only entities having sender signing policies are domains. -C.5. Changes since -allman-ssp-02 +C.6. Changes since -allman-ssp-02 o Removed user-granularity SSP and u= tag. o Replaced DKIMP resource record with a TXT record. o Changed name of the primary tag from "p" to "dkim". o Replaced lookup algorithm with one which traverses upward at most one level. o Added description of records to be published, and effect of wildcard records within the domain, on SSP. -C.6. Changes since -allman-ssp-01 +C.7. Changes since -allman-ssp-01 o Changed term "Sender Signing Policy" to "Sender Signing Practices". o Changed query methodology to use a separate DNS resource record type, DKIMP. o Changed tag values from SPF-like symbols to words. o User level policies now default to that of the domain if not specified. o Removed the "Compliance" section since we're still not clear on what goes here. o Changed the "parent domain" policy to only search up one level (assumes that subdomains will publish SSP records if appropriate). o Added detailed description of SSP check procedure. -C.7. Changes since -allman-ssp-00 +C.8. Changes since -allman-ssp-00 From a "diff" perspective, the changes are extensive. Semantically, the changes are: o Added section on "Third-Party Signatures and Mailing Lists" o Added "Compliance" (transferred from -base document). I'm not clear on what needs to be done here. o Extensive restructuring.