Network Working Group Sean Turner, IECA Internet Draft Santosh Chokhani, Cygnacom Solutions Intended Status: Standard Track October 19, 2009 Expires: April 19, 2010 Clearance Attribute and Authority Clearance Constraints Certificate Extension draft-ietf-pkix-authorityclearanceconstraints-03.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months 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 April 19, 2010. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Turner & Chokhani Expires April 19, 2010 [Page 1] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 Abstract This document defines the syntax and semantics for the Clearance attribute and the Authority Clearance Constraints extension in X.509 certificates. The Clearance attribute is used to indicate the clearance held by the subject. The Clearance attribute may appear in the subject directory attributes extension of a public key certificate or in the attributes field of an attribute certificate. The Authority Clearance Constraints certificate extension values in a Trust Anchor (TA), Certificate Authority (CA) public key certificates, and an Attribute Authority (AA) public key certificate in a public key certification path constrain the effective Clearance of the subject. Table of Contents 1. Introduction...................................................3 1.1. Terminology...............................................4 1.2. ASN.1 Syntax Notation.....................................4 2. Clearance Attribute............................................4 3. Authority Clearance Constraints Certificate Extension..........5 4. Clearance and Authority Clearance Constraints Processing in PKC............................................................6 4.1. Collecting Constraints....................................7 4.1.1. Certification Path Processing........................7 4.1.1.1. Inputs..........................................8 4.1.1.2. Initialization..................................8 4.1.1.3. Basic Certificate Processing....................8 4.1.1.4. Preparation for Certificate i+1.................9 4.1.1.5. Wrap-up Procedure...............................9 4.1.1.5.1. Wrap Up Clearance..........................9 4.1.1.6. Outputs........................................10 5. Clearance and Authority Clearance Constraints Processing in AC............................................................10 5.1. Collecting Constraints...................................11 5.1.1. Certification Path Processing.......................11 5.1.1.1. Inputs.........................................11 5.1.1.2. Initialization.................................11 5.1.1.3. Basic PKC Processing...........................12 5.1.1.4. Preparation for Certificate i+1................12 5.1.1.5. Wrap-up Procedure..............................12 5.1.1.5.1. Wrap Up Clearance.........................12 5.1.1.6. Outputs........................................12 6. Computing Intersection of permitted-clearances and AuthorityClearanceConstraints extension.......................12 7. Computing Intersection of securityCategories..................13 8. Recommended securityCategories................................15 Turner & Chokhani Expires April 19, 2010 [Page 2] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 9. Security Considerations.......................................15 10. IANA Considerations..........................................16 11. References...................................................16 11.1. Normative References....................................16 11.2. Informative References..................................17 Appendix A. ASN.1 Module.........................................18 Authors' Addresses...............................................20 1. Introduction Organizations that have implemented a security policy can issue certificates that include an indication of the clearance values held by the subject. The Clearance attribute indicates the security policy, the clearance levels held by the subject, and additional authorization information held by the subject. This specification makes use of the ASN.1 syntax for clearance from [RFC3281bis]. Clearance attribute may be placed in the subject directory attributes extension of a Public Key Certificate (PKC) or may be placed in a separate attribute certificate (AC). The placement of Clearance attribute in PKCs is desirable when the credentials such as PKCs need to be revoked when the clearance information changes or when clearance information is relatively static, and clearance information can be verified as part of PKC issuance process (e.g., using local databases). The placement of Clearance attribute in PKCs may also be made to simplify the infrastructure, to reduce the infrastructure design cost, or to reduce the infrastructure operations cost. An example of placement of Clearance attribute in PKCs in operational Public Key Infrastructure (PKI) is the Defense Messaging Service. An example of placement of attributes in PKCs is Qualified Certificates [RFC3739]. The placement of Clearance attribute in ACs is desirable when the clearance information is relatively dynamic and changes in the clearance information does not require revocation of credentials such as PKCs, or the clearance information can not be verified as part of PKC issuance process. Since [RFC3281bis] does not permit chain of ACs, the Authority Clearance Constraints extension may only appear in the PKCs of Certificate Authority (CA) or Attribute Authority (AA). The Authority Clearance Constraints extension may also appear in a trust anchor (TA) or may be associated with a TA. Some organizations have multiple TAs, CAs, and/or AAs and these organizations may wish to indicate to relying parties which clearance Turner & Chokhani Expires April 19, 2010 [Page 3] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 values from a particular TA, CA, or AA should be accepted. For example, consider the security policies described in [RFC3114], where a security policy has been defined for Amoco with three security classification values (HIGHLY CONFIDENTIAL, CONFIDENTIAL, and GENERAL). To constrain a CA for just one security classification, the Authority Clearance Constraints certificate extension would be included in the CA's PKC. Cross-certified domains can also make use of the Authority Clearance Constraints certificate extension to indicate which clearance values should be acceptable to relying parties. This document augments the certification path validation rules for PKCs in [RFC5280] and ACs in [RFC3281bis]. 1.1. Terminology 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 [RFC2119]. 1.2. ASN.1 Syntax Notation All X.509 PKC [RFC5280] extensions are defined using ASN.1 [X.680]. All X.509 AC [RFC3281bis] extensions are defined using ASN.1 [X.680]. 2. Clearance Attribute The Clearance attribute in a certificate indicates the clearances held by the subject. It uses the clearance attribute syntax from Section 4.4.6 of [RFC3281bis], which is included below for convenience, in the Attributes field. A certificate MUST include either zero or one instance of the Clearance attribute. If the Clearance attribute is present, it MUST contain a single value. The following object identifier identifies the Clearance attribute (either in the subject directory attributes extension of a PKC or in the Attributes field of an AC): id-at-clearance OBJECT IDENTIFIER ::= { joint-iso-ccitt(2) ds(5) attributeTypes(4) clearance(55) } The ASN.1 syntax for the Clearance attribute is as follows [PKI-ASN]: Clearance ::= SEQUENCE { policyId OBJECT IDENTIFIER, classList ClassList DEFAULT {unclassified}, Turner & Chokhani Expires April 19, 2010 [Page 4] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 securityCategories SET OF SecurityCategory {{ SupportedSecurityCategories }} OPTIONAL } ClassList ::= BIT STRING { unmarked (0), unclassified (1), restricted (2), confidential (3), secret (4), topSecret (5) } SECURITY-CATEGORY ::= TYPE-IDENTIFIER SecurityCategory { SECURITY-CATEGORY:Supported }::= SEQUENCE { type [0] IMPLICIT SECURITY-CATEGORY.&id({Supported}), value [1] EXPLICIT SECURITY-CATEGORY.&Type ({Supported}{@type}) } NOTE: SecurityCategory is shown exactly as it is in [PKI-ASN]. That module is an EXPLICIT tagged module whereas the module contained in this document is an IMPLICIT tagged module. The Clearance attribute takes its meaning from Section 4.4.6 of [RFC3281bis], which is repeated here for convenience: - policyId identifies the security policy to which the clearance relates. The policyId indicates the semantics of the classList and securityCategories fields. - classList identifies the security classifications. Six basic values are defined in bit positions 0 through 5 and more may be defined by an organizational security policy. - securityCategories provides additional authorization information. If a trust anchor's public key is used directly, then the Clearance associated with the trust anchor, if any, should be used as the effective clearance (also defined as effective-clearance for a certification path). 3. Authority Clearance Constraints Certificate Extension The Authority Clearance Constraints certificate extension indicates to the relying party what clearances should be acceptable for the Turner & Chokhani Expires April 19, 2010 [Page 5] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 subject of the AC or the subject of the last certificate in a PKC certification path. It is only meaningful in trust anchor, CA PKCs, or AA PKCs. A trust anchor, CA PKC, or AA PKC MUST include either zero or one instance of the Authority Clearance Constraints certificate extension. The Authority Clearance Constraints certificate extension MAY be critical or non-critical. Absence of this certificate extension in a TA, in a CA PKC, or in an AA PKC indicates that clearance of the subject of the AC or the subject of the last certificate in a PKC certification path containing the TA, the CA or the AA is not constrained by the respective TA, CA or AA. The following object identifier identifies the Authority Clearance Constraints certificate extension: id-pe-authorityClearanceConstraints OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) pe(1) 21 } The ASN.1 syntax for the Authority Clearance Constraints certificate extension is as follows: AuthorityClearanceConstraints ::= SEQUENCE SIZE (1..MAX) OF Clearance The syntax for Authority Clearance Constraints certificate extension contains Clearances that the CA or the AA asserts. The sequence MUST NOT include more than one entry with the same policyId. This constraint is enforced during Clearance and Authority Clearance Constraints Processing described below. If more than one entry with the same policyId is present in AuthorityClearanceConstraints certificate extension, the certification path is rejected. 4. Clearance and Authority Clearance Constraints Processing in PKC This section describes the processing of certification path when Clearance is asserted in PKC. User input, Authority Clearance Constraints certificate extension, and Clearance attribute processing determines the effective clearance (henceforth called effective-clearance) for the end PKC. User input, Authority Clearance Constraints certificate extension in the TA and in each PKC up to but not including the end PKC in a PKC certification path impact the effective-clearance. If there is more than one path to the end-entity PKC, each path is processed independently. The process involves two steps: Turner & Chokhani Expires April 19, 2010 [Page 6] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 1) collecting the Authority Clearance Constraints; and 2) using Authority Clearance Constraints in the certification path and the Clearance in the end PKC to determine the effective- clearance for the subject of the end PKC. Assuming a certification path consisting of n PKCs, the effective- clearance for the subject of the end PKC is the intersection of Clearance attribute in the subject PKC, Authority Clearance Constraints, if present, in trust anchor, user input, and all Authority Clearance Constraints present in intermediate PKCs. Any effective-clearance calculation algorithm that performs this calculation and provides the same outcome as the one from the algorithm described herein is considered compliant with the requirements of this RFC. When processing a certification path, Authority Clearance Constraints are maintained in one state variable: permitted-clearances. When processing begins, permitted-clearances is initialized to the user input value or special value all-clearances if Authority Clearance Constraints user input is not provided. The permitted-clearances state variable is updated by first processing Authority Clearance Constraints associated with the trust anchor, and then each time an intermediate PKC that contains an Authority Clearance Constraints certificate extension in the path is processed. When processing the end PKC, the value in the Clearance attribute in the end PKC is intersected with the permitted-clearances state variable. The output of Clearance attribute and Authority Clearance Constraint certificate extensions processing is the effective-clearance (which could also be an empty list), and a status indicator of either success or failure. If the status indicator was failure, then the process also returns a reason code. 4.1. Collecting Constraints Authority Clearance Constraints are collected from the user input, the trust anchor and the intermediate PKCs in a certification path. 4.1.1. Certification Path Processing When processing Authority Clearance Constraints certificate extension for the purposes of validating Clearance attribute in the end PKC, the processing described in this section or an equivalent algorithm MUST be performed in addition to the certification path validation. Turner & Chokhani Expires April 19, 2010 [Page 7] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 The processing is presented as additions to the certification path validation algorithm described in section 6 of [RFC5280]. Note that this RFC is fully consistent with [RFC5280]; however, it augments [RFC5280] with the following steps: . Ability to provide and process Authority Clearance Constraints as an additional input to the certification path processing engine . Requirement to process Authority Clearance Constraints present with Trust anchor information. 4.1.1.1. Inputs User input may include AuthorityClearanceConstraints structure or omit it. Trust anchor information may include the AuthorityClearanceConstraints structure to specify Authority Clearance Constraints for the trust anchor. The trust anchor may be constrained or unconstrained. 4.1.1.2. Initialization If user input includes AuthorityClearanceConstraints, set the permitted-clearances to the input value, otherwise, set the permitted-clearances to special value all-clearances. Examine the permitted-clearances for the same Policy ID appearing more then once. If a policyId appears more than once in the permitted-clearances state variable, set effective-clearance to an empty list, set error code to "multiple instances of same clearance", and exit with failure. If the trust anchor does not contain an AuthorityClearanceConstraints extension, continue at Section 4.1.1.3. Otherwise, execute the procedure described in Section 6 as an in-line macro by treating the trust anchor as a PKC. 4.1.1.3. Basic Certificate Processing If the PKC is the last PKC (i.e., certificate n), skip the steps listed in this section. Otherwise, execute the procedure described in Section 6 as an in-line macro. Turner & Chokhani Expires April 19, 2010 [Page 8] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 4.1.1.4. Preparation for Certificate i+1 No additional action associated with the Clearance attribute or AuthorityClearanceConstraints certificate extensions is taken during this phase of certification path validation as described in section 6 of [RFC5280]. 4.1.1.5. Wrap-up Procedure To complete the processing, perform the following steps for the last PKC (i.e., certificate n). Examine the PKC and verify that it does not contain more than one instance of Clearance attribute. If the PKC contains more than one instance of Clearance attribute, set effective-clearance to an empty list, set error code to "multiple instances of an attribute", and exit with failure. If the Clearance attribute is not present in the end PKC, set effective-clearance to an empty list and exit with success. Set effective-clearance to the Clearance attribute in the end PKC. 4.1.1.5.1. Wrap Up Clearance Examine effective-clearance and verify that it does not contain more than one value. If effective-clearance contains more than one value, set effective-clearance to an empty list, set error code to "multiple values", and exit with failure. If permitted-clearances is an empty list, set effective-clearance to an empty list and exit with success. If the permitted-clearances has special value of all-clearances, exit with success. Let us say policyId in effective-clearance is X. If the policyId X in effective-clearance is absent from the permitted-clearances, set effective-clearance to an empty list and exit with success. Assign those classList bits in effective-clearance a value of one (1) that have a value of one (1) both in effective-clearance and in the clearance structure in permitted-clearances associated with policyId X. Assign all other classList bits in effective-clearance a value of zero (0). Turner & Chokhani Expires April 19, 2010 [Page 9] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 If none of the classList bits have a value of one (1) in effective- clearance, set effective-clearance to an empty list and exit with success. Set the securityCategories in effective-clearance to the intersection of securityCategories in effective-clearance and in permitted- clearances using the algorithm described in Section 7. Note that an empty SET is represented by simply omitting the SET. Exit with Success. 4.1.1.6. Outputs If certification path validation processing succeeds, effective- clearance contains the effective clearance for the subject of the certification path. Processing also returns success or failure indication and reason for failure, if applicable. 5. Clearance and Authority Clearance Constraints Processing in AC This section describes the processing of certification path when Clearance is asserted in an AC. Relevant to processing are: one TA; 0 or more CA PKCs; 0 or 1 AA PKC; and 1 AC. User input, Authority Clearance Constraints certificate extension and Clearance attribute processing determines the effective clearance (henceforth called effective-clearance) for the AC. User input, Authority Clearance Constraints certificate extension in the TA and in each PKC up to and including the AA PKC in a certification path impact the effective-clearance. If there is more than one path to the AA PKC, each path is processed independently. The process involves two steps: 1) collecting the Authority Clearance Constraints; and 2) using Authority Clearance Constraints in the PKC certification path and the Clearance in the AC to determine the effective- clearance for the subject of the AC. The effective-clearance for the subject of the AC is the intersection of Clearance in the subject AC, Authority Clearance Constraints, if present, in trust anchor, user input, and all Authority Clearance Constraints present in PKC certification path from the TA to the AA. Any effective-clearance calculation algorithm that performs this calculation and provides the same outcome as the one from the algorithm described herein is considered compliant with the requirements of this RFC. Turner & Chokhani Expires April 19, 2010 [Page 10] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 Authority Clearance Constraints is maintained in one state variable: permitted-clearances. When processing begins, permitted-clearances is initialized to user input or special value all-clearances if Authority Clearance Constraints user input is not provided. The permitted-clearances state variable is updated by first processing Authority Clearance Constraints associated with the trust anchor, and then each time a PKC (other than AC holder PKC) that contains an Authority Clearance Constraints certificate extension in the path is processed. When processing the AC, the value in the Clearance attribute in the AC is intersected with the permitted-clearances state variable. The output of Clearance and Authority Clearance Constraint certificate extensions processing is the effective-clearance, which could also be an empty list; and success or failure with reason code for failure. 5.1. Collecting Constraints Authority Clearance Constraints are collected from the user input, the trust anchor and all the PKCs in a PKC certification path. 5.1.1. Certification Path Processing When processing Authority Clearance Constraints certificate extension for the purposes of validating Clearance in the AC, the processing described in this section or an equivalent algorithm MUST be included in the certification path validation. The processing is presented as additions to the PKC certification path validation algorithm described in section 6 of [RFC5280] for the AA PKC certification path and the algorithm described in section 5 of [RFC3281bis] for the AC validation. Also see note related to [RFC5280] augmentation in Section 4.1.1. 5.1.1.1. Inputs Same as Section 4.1.1.1. In addition, let us assume that the PKC certification path for the AA consists of n certificates. 5.1.1.2. Initialization Same as Section 4.1.1.2. Turner & Chokhani Expires April 19, 2010 [Page 11] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 5.1.1.3. Basic PKC Processing Same as Section 4.1.1.3. except that the logic is applied to all n PKCs. 5.1.1.4. Preparation for Certificate i+1 Same as Section 4.1.1.4. 5.1.1.5. Wrap-up Procedure To complete the processing, perform the following steps for the AC. Examine the AC and verify that it does not contain more than one instance of Clearance attribute. If the AC contains more than one instance of Clearance attribute, set effective-clearance to an empty list, set error code to "multiple instances of an attribute", and exit with failure. If the Clearance attribute is not present in the AC, set effective- clearance to an empty list and exit with success. Set effective-clearance to the Clearance attribute in the AC. 5.1.1.5.1. Wrap Up Clearance Same as Section 4.1.1.5.1. 5.1.1.6. Outputs Same as Section 4.1.1.6. In addition, apply AC processing rules described in Section 5 of [RFC3281bis]. 6. Computing Intersection of permitted-clearances and AuthorityClearanceConstraints extension Examine the PKC and verify that it does not contain more than one instance of AuthorityClearanceConstraints extension. If the PKC contains more than one instance of AuthorityClearanceConstraints extension, set effective-clearance to an empty list, set error code to "multiple extension instances", and exit with failure. If the AuthorityClearanceConstraints certificate extension is not present in the PKC, no action is taken, and the permitted-clearances value is unchanged. Turner & Chokhani Expires April 19, 2010 [Page 12] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 If the AuthorityClearanceConstraints certificate extension is present in the PKC, set the variable temp-clearances to AuthorityClearanceConstraints certificate extension. Examine the temp-clearances for the same Policy ID appearing more then once. If a policyId appears more than once in the temp-clearances state variable, set effective-clearance to an empty list, set error code to "multiple instances of same clearance", and exit with failure. If the AuthorityClearanceConstraints certificate extension is present in the PKC and permitted-clearances contains the all-clearances special value, then assign permitted-clearances the value of the temp-clearances. If the AuthorityClearanceConstraints certificate extension is present in the PKC and permitted-clearances does not contain the all- clearances special value, take the intersection of temp-clearances and permitted-clearances by repeating the following steps for each clearance in the permitted-clearances state variable: - If the policyId associated with the clearance is absent in the temp-clearances, delete the clearance structure associated with the policyID from the permitted-clearances state variable. - If the policyId is present in the temp-clearances: -- For every classList bit, assign the classList bit a value of one (1) for the policyId in permitted-clearances state variable if the bit is one (1) in both the permitted- clearances state variable and the temp-clearances for that policyId; otherwise assign the bit a value of zero (0). -- If no bits are one (1) for the classList, delete the clearance structure associated with the policyId from the permitted- clearances state variable and skip the next step of processing securityCategories. -- For the policyId in permitted-clearances, set the securityCategories to the intersection of securityCategories for the policyId in permitted-clearances and in temp- clearances using the algorithm described in Section 7. Note that an empty SET is represented by simply omitting the SET. 7. Computing Intersection of securityCategories The algorithm described in here has the idempotency, associative, and commutative properties, like the rest of the processing rules in this document. Turner & Chokhani Expires April 19, 2010 [Page 13] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 This section describes how to compute the intersection of securityCategories A and B. It uses the state variable temp-set. It also uses temporary variables X and Y Set the SET temp-set to empty. Set X = A and Y = B If SET X is empty (i.e., securityCategories is absent), return temp- set. If SET Y is empty (i.e., securityCategories is absent), return temp- set. For each type OID in X, if all the elements for the type OID in X and if and only if all the elements for that type OID in Y are identical, add those elements to temp-set and delete those elements from X and Y. Note: identical means that if the element with the type OID and given value is present in X, it is also present in Y with the same type OID and given value and vice versa. Delete the elements from X and from Y. If SET X is empty (i.e., securityCategories is absent), return temp- set. If SET Y is empty (i.e., securityCategories is absent), return temp- set. For every element (i.e., SecurityCategory) in the SET X carry out the following steps: 1. If there is no element in SET Y with the same Type OID as the type OID in the element from SET X, go to step 5. 2. If there is an element in SET Y with the same Type OID and value as in the element in SET X, carry out the following steps: a) If the element is not present in the SET temp-set, add an element containing the Type OID and the value to the SET temp-set. 3. If the processing semantics of Type OID in the element in SET X is not known, go to step 5. 4. For each element in SET Y, do the following: Turner & Chokhani Expires April 19, 2010 [Page 14] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 a) If the Type OID of the element in SET Y is not the same as the element in SET X being processed, go to step 4.d. b) Perform Type OID specific intersection of the value in the element in SET X with the value in the element in SET Y. c) If the intersection is not empty, and the element representing the Type OID and intersection value is not already present in temp-set, add the element containing the Type OID and intersection value as an element to temp- set. d) Continue Do 5. If more elements remain in SET X, process the next element starting with step 1. Return temp-set. 8. Recommended securityCategories This RFC also include a recommended securityCategories as follows: recommended-category SECURITY-CATEGORY ::= { BIT STRING IDENTIFIED BY OID } The above structure is provided as an example. To use this structure, the object identifier (OID) needs to be registered and the semantics of the bits in the bit string need to be enumerated. Note that Type specific intersection of two values for this Type will be simply setting the bits that are set in both values. If the resulting intersection has none of the bits set, the intersection is considered empty. 9. Security Considerations Certificate issuers must recognize that absence of the AuthorityClearanceConstraints in a CA or AA certificate means that in terms of the clearance, the subject Authority is not constrained. Absence of Clearance attribute in a certificate means that the subject has not been assigned any clearance. If there is no Clearance associated with a TA, it means that the TA has not been assigned any clearance. Turner & Chokhani Expires April 19, 2010 [Page 15] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 If the local security policy considers the clearance held by a subject or those supported by a CA or AA to be sensitive, then the Clearance attribute or Authority Clearance Constraints should only be included if the subject's and Authority's certificate can be privacy protected. Also in this case, distribution of trust anchors and associated Authority Clearance Constraints extension or Clearance must also be privacy protected. 10. IANA Considerations None. Please remove this section prior to publication as an RFC. 11. References 11.1. Normative References [PKI-ASN] Hoffman, P., and J. Schaad, "New ASN.1 Modules for PKIX", draft-ietf-pkix-new-asn1-07, work-in-progress. /*** RFC EDITOR: Please replace PKI-ASN with RFCXYZA when draft-ietf- pkix-new-asn1 is published. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3281bis] Farrell, S., Housley, R., and S. Turner, "An Internet Attribute Certificate Profile for Authorization: Update", draft-ietf-pkix-3281update-05, work-in- progress. /*** RFC EDITOR: Please replace RFC3281bis with RFCXYZA when draft- ietf-pkix-3281update is published. [RFC5280] Cooper, D. et. al., "Internet X.509 Public Key Infrastructure Certificate and Certification Revocation List (CRL) Profile", RFC 5280, May 2008. [X.680] ITU-T Recommendation X.680 (2002) | ISO/IEC 8824- 1:2002. Information Technology - Abstract Syntax Notation One. Turner & Chokhani Expires April 19, 2010 [Page 16] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 11.2. Informative References [RFC3114] Nicolls, W., "Implementing Company Classification Policy with S/MIME Security Label", RFC3114, May 2002. [RFC3739] Santesson, S. et. al., "Internet X.509 Public Key Infrastructure: Qualified Certificate Profile", RFC 3739, March 2004. Turner & Chokhani Expires April 19, 2010 [Page 17] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 Appendix A. ASN.1 Module This appendix provides the normative ASN.1 definitions for the structures described in this specification using ASN.1 as defined in X.680. ClearanceConstraints { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) mod(0) 46 } DEFINITIONS IMPLICIT TAGS ::= BEGIN -- EXPORTS ALL -- IMPORTS -- IMPORTS from [PKI-ASN] id-at-clearance, Clearance FROM PKIXAttributeCertificate-2009 { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-attribute-cert-02(47) } -- IMPORTS from [PKI-ASN] EXTENSION, SECURITY-CATEGORY FROM PKIX-CommonTypes-2009 { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-pkixCommon-02(57) } ; -- Clearance attribute OID and syntax -- The following is a '02 version for clearance. -- It is included for convenience. -- id-at-clearance OBJECT IDENTIFIER ::= -- { joint-iso-ccitt(2) ds(5) attributeTypes(4) clearance (55) } Turner & Chokhani Expires April 19, 2010 [Page 18] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 -- Clearance ::= SEQUENCE { -- policyId OBJECT IDENTIFIER, -- classList ClassList DEFAULT {unclassified}, -- securityCategories SET OF SecurityCategory -- {{SupportSecurityCategories }} OPTIONAL -- } -- ClassList ::= BIT STRING { -- unmarked (0), -- unclassified (1), -- restricted (2), -- confidential (3), -- secret (4), -- topSecret (5) -- } -- SECURITY-CATEGORY ::= TYPE-IDENTIFIER -- NOTE that the module SecurityCategory is taken from a module -- that uses EXPLICIT tags [PKI-ASN]. If Clearance was not imported -- from [PKI-ASN] and the comments were removed from the ASN.1 -- contained herein, then the IMPLICIT in type could also be removed -- with no impact on the encoding. -- SecurityCategory { SECURITY-CATEGORY:Supported } ::= SEQUENCE { -- type [0] IMPLICIT SECURITY-CATEGORY.&id({Supported}), -- value [1] EXPLICIT SECURITY-CATEGORY.&Type -- ({Supported}{@type}) -- } -- Authority Clearance Constraints certificate extension OID -- and syntax id-pe-clearanceConstraints OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) pe(1) 21 } authorityClearanceConstraints EXTENSION ::= { SYNTAX AuthorityClearanceConstraints IDENTIFIED BY id-pe-clearanceConstraints } AuthorityClearanceConstraints ::= SEQUENCE SIZE (1..MAX) OF Clearance END Turner & Chokhani Expires April 19, 2010 [Page 19] Internet-Draft Clearance and Authority Clearance Constraints Oct 2009 Authors' Addresses Sean Turner IECA, Inc. 3057 Nutley Street, Suite 106 Fairfax, VA 22031 USA EMail: turners@ieca.com Santosh Chokhani CygnaCom Solutions, Inc. EMail: SChokhani@cygnacom.com Turner & Chokhani Expires April 19, 2010 [Page 20]