One document matched: draft-ietf-smime-seclabel-00.txt

		  Implementing Company Classification Policy 
			with the S/MIME Security Label
		      <draft-ietf-smime-seclabel-00.txt>

Status of this memo

This document is an Internet-Draft and is in full conformance with all 
provisions of Section 10 of [RFC2026].

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<<Comments are contained in angle brackets like this.>>

1.   Introduction
     
This document discusses how company security policy for data classification can 
be mapped to the S/MIME classification label.  Actual policies from 3 companies 
are used to provide worked examples.  

Security labels are an optional security service for S/MIME. A security label is 
a set of security information regarding the sensitivity of the content that is 
protected by S/MIME encapsulation. A security label can be a bound attribute of 
the original message content, the encrypted body, or both.  The syntax and 
processing rules for security labels are described in [ESS].

The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT','SHOULD', 
'SHOULD NOT', 'RECOMMENDED',  'MAY', and 'OPTIONAL' in this document are to be 
interpreted as described in [MUSTSHOULD]. 

This draft is being discussed on the 'ietf-smime' mailing list.  To join the 
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1.1 Information Classification Policies

Information is an asset, but not all information has the same value for a 
business. Not all information needs to be protected as strongly as other 
information.  

Research and development plans, marketing strategies and manufacturing quality 
specifications developed and used by a company provide competitive advantage.  
This type of information needs stronger protective measures than other 
information, which if disclosed or modified, would cause little or no damage to 
the company.

Other types of information such as internal organization charts, employee lists 
and policies may need little and no protective measures based on value the 
organization places on it.

A corporate information classification policy defines how its information assets 
are to be protected.  It provides guidance to employees on how to classify 
information assets.  It defines how to label and protect an asset based on its 
classification and state (e.g. facsimile, electronic transfer, storage, 
shipping, etc.).

1.2 Access Control and Security Labels

"Access control" is a means of enforcing authorizations. There are a variety of 
access control methods that are based on different types of policies and rely on 
different security mechanisms.

-  Rule based access control is based on policies that can be algorithmically 
expressed. 

-  Identity based access control is based on a policy which applies explicitly 
to an individual person or host entity, or to a defined group of such entities.  
Once identity has been authenticated, if the identity is verified to be on the 
access list, then access is granted.

-  Rank base access control is based on a policy of hierarchical positions in an 
organization.  A rank-based policy would define what information that the 
position of Partner or Senior Consultant could access.

-  Role based access control is based on a policy of hierarchical roles in an 
organization.  The role-based policy would define what information that the role 
of Executive, Vice President or Staff could access.

Rule, rank and role-based access control methods can rely on a security label as 
the security mechanism to convey the sensitivity or classification of the 
information.  When verifying an S/MIME encapsulated message, the sensitivity 
information in the messages security label can be compared with the recipient's 
authorizations to determine if the recipient is allowed to access the protected 
content.

An S/MIME security label may be included as an authenticated attribute in the 
inner (or only) signature or the outer signature.  The inner signature would be 
used for access control decisions related to the plaintext original content, 
while he outer signature would be used for access control decisions related to 
the encrypted message.

1.3 User Authorizations

Users need to be granted authorizations to access information that has been 
classified by an authority.  The sending and receiving agent need to be able to 
securely determine the users authorizations for access control processing.

[X.509] and the Internet profile for X.509 certificates [CERTCRL] do not define 
the means to represent and convey authorizations in a certificate.  

[X.501] defines how to represent authorization in the form of a clearance 
attribute.  The clearance attribute identifies the security policy in force to 
which a list of possible classifications and security categories relates.  
        
[X.501] also notes two means for binding the clearance to a named entity: an 
Attribute Certificate and a Certificate extension field (e.g., within the 
subjectDirectoryAttribute extension). 

[AC509] defines a profile of X.509 Attribute Certificate (AC) suitable for use 
with authorization information within Internet Protocols. One of the defined 
attributes is Clearance, which carries clearance (security labeling) information 
about the AC owner.  The syntax for Clearance is imported from [X.501].

2. Developed Examples

2.1 Classification Policies

The following describes the information classification policies in effect at 3 
companies.

2.1.1 Amoco Corporation

The description for the Amoco information classification policy was taken from 
the Amoco Computer Security Guidelines.  Amoco classifies its information assets 
based on confidentiality and integrity and defines 3 hierarchical 
classifications for each.

Highly Confidential - Information whose unauthorized disclosure will cause the 
company severe financial, legal or reputation damage. Examples:  Certain 
acquisitions, bid economics, negotiation strategies.

Confidential - Information whose unauthorized disclosure may cause the company 
financial, legal, or reputation damage. Examples:  Employee Personnel & Payroll 
Files, some interpreted Exploration Data.

General - Information that, because of its personal, technical, or business 
sensitivity is restricted for use within the company. Unless otherwise 
classified, all information within Amoco is in this category.

Maximum - Information whose unauthorized modification and destruction will cause 
the company severe financial, legal, or reputation damage.

Medium - Information whose unauthorized modification and destruction may cause 
the company financial, legal, or reputation damage. Examples: Electronic Funds, 
Transfer, Payroll, and Commercial Checks

Minimum - Although an error in this data would be of minimal consequence, this 
is still important company information and therefore will require some minimal 
controls to ensure a minimal level of assurance that the integrity of the data 
is maintained. This applies to all data that is not placed in one of the above 
classifications. Examples: Lease Production Data, Expense Data, Financial Data, 
and Exploration Data.

2.1.2 Caterpillar, Inc.

The description for the Caterpillar information classification policy is taken 
from the Caterpillar Information Protection Guidelines.  Caterpillar classifies 
its information assets based on confidentiality and defines 4 hierarchical 
classifications.  

Caterpillar Confidential Red - Provides a significant competitive advantage. 
Disclosure would cause severe damage to operations. Relates to or describes a 
long-term strategy or critical business plans. Disclosure would cause regulatory 
or contractual liability. Disclosure would cause severe damage to our reputation 
or the public image. Disclosure would cause a severe loss of market share or the 
ability to be first to market. Disclosure would cause a loss of an important 
customer, shareholder, or business partner. Disclosure would cause a long-term 
or severe drop in stock value. Strong likelihood somebody is seeking to acquire 
this information.

Caterpillar Confidential Yellow - Provides a competitive advantage. Disclosure 
could cause moderate damage to the company or an individual. Relates to or 
describes an important part of the operational direction of the company over 
time. Important technical or financial aspects of a product line or a business 
unit. Disclosure could cause a loss of Customer or Shareholder confidence. 
Disclosure could cause a temporary drop in stock value. A likelihood that 
somebody could seek to acquire this information.

Caterpillar Confidential Green - Might provide a business advantage over those 
who do not have access to the same information. Might be useful to a competitor. 
Not easily identifiable by inspection of a product. Not generally known outside 
the company or available from public sources. Generally available internally. 
Little competitive interest.

Caterpillar Public - Would not provide a business or competitive advantage. 
Routinely made available to interested members of the General Public.  Little or 
no competitive interest.

2.1.3 Whirlpool Corporation

The description for the Whirlpool information classification policy is taken 
from the Whirlpool Information Protection Policy.  Whirlpool classifies its 
information assets based on confidentiality and defines 2 hierarchical 
classifications.  The policy states that:

"All information generated by or for Whirlpool, in whatever form, written, 
verbal, or electronic, is to be treated as WHIRLPOOL INTERNAL or WHIRLPOOL 
CONFIDENTIAL.  Classification of information in either category depends on its 
value, the impact of unauthorized disclosure, legal requirements, and the manner 
in which it needs to be used by the company.  Some WHIRLPOOL INTERNAL 
information may be authorized for public release."

WHIRLPOOL CONFIDENTIAL - A subset of Whirlpool Internal information, the 
unauthorized disclosure or compromise of which would likely have an adverse 
impact on the companys competitive position, tarnish its reputation, or 
embarrass an individual.  Examples: Customer, financial, pricing, or personnel 
data; merger/acquisition, product, or marketing plans; new product designs, 
proprietary processes and systems.

WHIRLPOOL INTERNAL - All forms of proprietary information originated or owned by 
Whirlpool, or entrusted to it by others.  Examples: Organization charts, 
policies, procedures, phone directories, some types of training materials.

WHIRLPOOL PUBLIC - Information officially released by Whirlpool for widespread 
public disclosure. Example: Press releases, public marketing materials, 
employment advertising, annual reports, product brochures, the public web site, 
etc

The policy also states that privacy markings are allowable. Specifically:

For WHIRLPOOL INTERNAL, additional markings or caveats are option at the 
discretion of the information owner.

For WHIRLPOOL CONFIDENTIAL, add additional marking or caveats as necessary to 
comply with regulatory or heightened security requirements.  Examples:  MAKE NO 
COPIES, THIRD PARTY CONFIDENTIAL, ATTORNEY-CLIENT PRIVILEGED DOCUMENT, 
DISTRIBUTION LIMITED TO ____, COVERED BY A NON-ANALYSIS AGREEMENT.

2.2 S/MIME Classification Label Developed Examples

[ESS] defines the ESSSecurityLabel syntax and processing rules.  This section 
builds upon those definitions to define detailed example policies.

2.2.1 Security Label Components

The examples are detailed using the various components of the eSSSecurity Label 
syntax.

2.2.1.1 Security Policy Identifier

A security policy is a set of criteria for the provision of security services. 
The eSSSecurityLabel security-policy-identifier is used to identify the security 
policy in force to which the security label relates. It indicates the semantics 
of the other security label components.

For the example policies, the following security policy object identifiers are 
defined:  

<<Need to obtain test S/MIME OIDs.>>

Amoco security-policy-identifier ::= { }

Caterpillar security-policy-identifier ::= { }

Whirlpool security-policy-identifier ::= { }

2.2.1.2 Security Classification

The security classification values and meanings are defined by the governing 
company policies. The security-classification values defined are hierarchical 
and do not use integers 0 through 5.

Amoco-SecurityClassification ::=  {
  amoco general (6),
  amoco confidential (7),
  amoco highly confidential (8),
  amoco minimum (9),
  amoco medium (10),
  amoco maximum (11)  }  (0..ub-integer-options)

Caterpillar-SecurityClassification values ::=  {
  caterpillar public (6),
  caterpillar green (7),
  caterpillar yellow (8),
  caterpillar red (9) }  (0..ub-integer-options)

Whirlpool-SecurityClassification values ::=  {
  whirlpool public (6),
  whirlpool internal (7),
  whirlpool confidential (8) }  (0..ub-integer-options)

2.2.1.3 Privacy Mark

Privacy marks are specified the Whirlpool policy. The policy provides examples 
of possible marking but other can be defined by users as necessary.  User 
specified privacy marks are defined using the following syntax.

<<Need to develop the syntax.  Suggestions?>>

2.2.1.4 Security Categories

Security categories or caveats are not specified to any of the sample policies. 
However, they are used in at least 2 of the companies informally.  Though formal 
security categories are not defined, some proprietary information does need more 
granular access control.  A category can be based organizationally or by project 
(i.e., Legal or Project Vallor).  User specified security categories are defined 
using the following syntax.

<< Need to develop the syntax.  Suggestions?>>

2.2.2 Attribute Owner Clearance

The security clearance and category authorizations for the user are defined in 
the clearance attribute. 

2.2.2.1 Amoco User

Clearance  ::=  SEQUENCE {
           policyId  OBJECT IDENTIFIER,
           classList ClassList DEFAULT {general},
           securityCategories
                      SET OF SecurityCategory  OPTIONAL
           }

           ClassList  ::=  BIT STRING {
               amoco general              (6),
               amoco confidential         (7),
               amoco highly confidential  (8),
           }

           SecurityCategory ::= SEQUENCE {
               type      [0]  IMPLICIT OBJECT IDENTIFIER,
               value     [1]  ANY DEFINED BY type
           }

2.2.2.1 Caterpillar User

Clearance  ::=  SEQUENCE {
           policyId  OBJECT IDENTIFIER,
           classList ClassList DEFAULT {general},
           securityCategories
                      SET OF SecurityCategory  OPTIONAL
           }

           ClassList  ::=  BIT STRING {
               caterpillar public              (6),
               caterpillar confidential greeen (7),
               caterpillar confidential yellow (8),
               caterpillar confidential red    (9)
           }

           SecurityCategory ::= SEQUENCE {
               type      [0]  IMPLICIT OBJECT IDENTIFIER,
               value     [1]  ANY DEFINED BY type
           }

2.2.2.1 Whirlpool User

Clearance  ::=  SEQUENCE {
           policyId  OBJECT IDENTIFIER,
           classList ClassList DEFAULT {general},
           securityCategories
                      SET OF SecurityCategory  OPTIONAL
           }

           ClassList  ::=  BIT STRING {
               whirlpool public        (6),
               whirlpool internal      (7),
               whirlpool confidential  (8),
           }

           SecurityCategory ::= SEQUENCE {
               type      [0]  IMPLICIT OBJECT IDENTIFIER,
               value     [1]  ANY DEFINED BY type
           }

2.2.3 Additional ESSSecurityLabel Processing Guidance

<<What needs to be addressed here?>>

<<How does the app know how to interpret the values into meaningful text?>>

When originating enveloped data, the agents MUST allow the security label of the 
data to be specified.

Upon successful access control processing, the agents SHOULD display to the 
recipient the security label for the encrypted data.

<<What is missing?>>

3. Security Considerations

All security considerations from [CMS] and [ESS] apply to applications that use 
procedures described in this document.

A. References

[AC509] Farrell, S., Housley, R., "An Internet AttributeCertificate Profile for 
Authorization", draft-ietf-pkix-ac509prof-01.txt.

[CMS] Housley, R., "Cryptographic Message Syntax", RFC 2630.

[ESS] Hoffman, P., Editor, "Enhanced Security Services for S/MIME", RFC 2634.

[MUSTSHOULD] Bradner, S., "Key Words for Use in RFCs to Indicate Requirement 
Levels",
RFC 2119.

[X.501] "ITU-T Recommendation X.501 : Information Technology - Open Systems 
Interconnection - The Directory: Models", 1993.

[X.509] "ITU-T Recommendation X.509 (1997 E): Information              
Technology - Open Systems Interconnection - The Directory: Authentication 
Framework", June 1997.

B. Acknowledgements

I would like to thanks Russ Housley for helping me through the process of 
developing this document.  I would also like to thank the good people at (BP) 
Amoco, Caterpillar and Whirlpool who allowed me to use their policies as the 
real examples that make this document possible.

C. Authors Address

Weston Nicolls
Ernst & Young LLP
111 N. Canal St
Chicago, IL 60606
(312) 879-2075
weston.nicolls@ey.com

D. Open issues: