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Compressed Data Content Type for Cryptographic Message Syntax (CMS) (RFC3274)

IP.com Disclosure Number: IPCOM000008361D
Original Publication Date: 2002-Jun-01
Included in the Prior Art Database: 2002-Jun-11
Document File: 7 page(s) / 11K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

P. Gutmann: AUTHOR

Abstract

This document defines a format for using compressed data as a Cryptographic Message Syntax (CMS) content type. Compressing data before transmission provides a number of advantages, including the elimination of data redundancy which could help an attacker, speeding up processing by reducing the amount of data to be processed by later steps (such as signing or encryption), and reducing overall message size. Although there have been proposals for adding compression at other levels (for example at the MIME or SSL level), these don't address the problem of compression of CMS content unless the compression is supplied by an external means (for example by intermixing MIME and CMS).

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Network Working Group                                         P. Gutmann

Request for Comments: 3274                        University of Auckland

Category: Standards Track                                      June 2002

                   Compressed Data Content Type for

                   Cryptographic Message Syntax (CMS)

Status of this Memo

   This document specifies an Internet standards track protocol for the

   Internet community, and requests discussion and suggestions for

   improvements.  Please refer to the current edition of the "Internet

   Official Protocol Standards" (STD 1) for the standardization state

   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document defines a format for using compressed data as a

   Cryptographic Message Syntax (CMS) content type.  Compressing data

   before transmission provides a number of advantages, including the

   elimination of data redundancy which could help an attacker, speeding

   up processing by reducing the amount of data to be processed by later

   steps (such as signing or encryption), and reducing overall message

   size.  Although there have been proposals for adding compression at

   other levels (for example at the MIME or SSL level), these don't

   address the problem of compression of CMS content unless the

   compression is supplied by an external means (for example by

   intermixing MIME and CMS).

1. Introduction

   This document describes a compressed data content type for CMS.  This

   is implemented as a new ContentInfo type and is an extension to the

   types currently defined in CMS [RFC2630].  CMS implementations SHOULD

   include support for the CompressedData content type.

   The format of the messages are described in ASN.1 [ASN1].

Gutmann                     Standards Track                     [Page 1]

RFC 3274          Compressed Data Content Type for CMS         June 2002

   The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",

   "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be

   interpreted as described in [RFC2119].

1.1 Compressed Data Content Type

   The compressed-data content type consists of content of any type,

   compressed using a specified algorithm.  The following object

   identifier identifies the compressed-data content type:

      id-ct-compressedData OBJECT IDENTIFIER ::= { iso(1) member-body(2)

        us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) ct(1) 9 }

   The compressed-data content type shall have ASN.1 type

   CompressedData:

      CompressedData ::= SEQUENCE {

        version CMSVersion,

        compressionAlgorithm CompressionAlgorithmIdentifier,

        encapContentInfo EncapsulatedContentInfo

        }

   The fields of type CompressedData have the following meanings:

      version is the syntax version number.  It MUST be 0.  Details of

      the CMSVersion type are discussed in CMS [RFC2630], section

      10.2.5.

      compressionAlgorithm is a compression algorithm identifier, as

      defined in section 2.

      encapContentInfo is the content which is compressed.  Details of

      the EncapsulatedContentInfo type are discussed in CMS [RFC2630],

      section 5.2.

   Implementations SHOULD use the SMIMECapabilities attribute to

   indicate their ability to process compre...