Redaction of Potentially Sensitive Data from Mail Abuse Reports
RFC 6590
Internet Engineering Task Force (IETF) J. Falk, Ed.
Request for Comments: 6590 Return Path
Category: Standards Track M. Kucherawy, Ed.
ISSN: 2070-1721 Cloudmark
April 2012
Redaction of Potentially Sensitive Data from Mail Abuse Reports
Abstract
Email messages often contain information that might be considered
private or sensitive, per either regulation or social norms. When
such a message becomes the subject of a report intended to be shared
with other entities, the report generator may wish to redact or elide
the sensitive portions of the message. This memo suggests one method
for doing so effectively.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6590.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Falk & Kucherawy Standards Track [Page 1]
RFC 6590 Redaction April 2012
Table of Contents
1. Introduction ....................................................2
2. Key Words .......................................................3
3. Recommended Practice ............................................3
4. Transformation Mechanisms .......................................4
5. Security Considerations .........................................5
5.1. General ....................................................5
5.2. Digest Collisions ..........................................5
5.3. Information Not Redacted ...................................5
6. Privacy Considerations ..........................................6
7. References ......................................................6
7.1. Normative References .......................................6
7.2. Informative References .....................................6
Appendix A. Example ................................................7
Appendix B. Acknowledgements .......................................8
1. Introduction
The Abuse Reporting Format [ARF] defines a message format for sending
reports of abuse in the messaging infrastructure, with an eye toward
automating both the generation and consumption of those reports.
For privacy considerations, it might be the policy of a report
generator to anonymize, or obscure, portions of the report that might
identify an end user who caused the report to be generated. This has
come to be known in feedback loop parlance as "redaction". Precisely
how this is done is unspecified in [ARF], as it will generally be a
matter of local policy. That specification does admonish generators
against being too overzealous with this practice, as obscuring too
much data makes the report non-actionable.
Previous redaction practices, such as replacing local-parts of
addresses with a uniform string like "xxxxxxxx", frustrated any kind
of prioritizing or grouping of reports. This memo presents a
practice for conducting redaction in a manner that allows a report
receiver to detect that two reports were caused by the same end user,
without revealing the identity of that user. That is, the report
receiver can use the redacted string, such as an obscured email
address, to determine that two such unredacted strings were
identical; the reports originally contained the same address.
Falk & Kucherawy Standards Track [Page 2]
RFC 6590 Redaction April 2012
Generally, it is assumed that the recipient-identifying fields of a
message, when copied into a report, are to be obscured to protect the
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