KEYPROV Working Group Sean Turner, IECA
Internet Draft Russ Housley, Vigil Security
Intended Status: Standard Track July 14, 2008
Expires: January 14, 2009
Symmetric Key Package Content Type
draft-ietf-keyprov-symmetrickeyformat-03.txt
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Copyright (C) The IETF Trust (2008).
Abstract
This document defines the symmetric key format content type. It is
transport independent. The Cryptographic Message Syntax can be used
to digitally sign, digest, authenticate, or encrypt this content
type.
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Table of Contents
1. Introduction...................................................2
1.1. Requirements Terminology..................................2
1.2. ASN.1 Syntax Notation.....................................2
2. Use Cases......................................................3
2.1. Online Use Cases..........................................3
2.1.1. Transport of Keys from Server to Cryptomodule........3
2.1.2. Transport of Keys from Cryptomodule to Cryptomodule..3
2.1.3. Transport of Keys from Cryptomodule to Server........3
2.1.4. Server to Server Bulk Import/Export of Keys..........4
2.2. Offline Use Cases.........................................4
2.2.1. Server to Server Bulk Import/Export of Keys..........4
3. Symmetric Key Package Content Type.............................5
4. Security Considerations........................................6
5. IANA Considerations............................................6
6. References.....................................................6
6.1. Normative References......................................6
6.2. Non-Normative References..................................7
APPENDIX A: ASN.1 Module..........................................8
1. Introduction
This document defines the symmetric key format content type. It is
transport independent. The Cryptographic Message Syntax [RFC3852] can
be used to digitally sign, digest, authenticate, or encrypt this
content type.
1.1. Requirements 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
The key package is defined using the ASN.1 [X.680, X.681, X.682,
X.683].
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2. Use Cases
These use cases help in understanding the applicability of this
specification to real world situations.
2.1. Online Use Cases
This section describes the use cases related to provisioning the keys
using an online provisioning protocol such as [DSKPP].
2.1.1. Transport of Keys from Server to Cryptomodule
For example, a mobile device user wants to obtain a symmetric key for
use with a cryptomodule on the device. The cryptomodule client from
vendor A initiates the provisioning process against a provisioning
system from vendor B using a standards-based provisioning protocol
such as [DSKPP]. The provisioning entity delivers one or more keys
in a standard format that can be processed by the mobile device.
For example, in a variation of the above, instead of the user's
mobile phone, a key is provisioned in the user's soft token
application on a laptop using a network-based online protocol. As
before, the provisioning system delivers a key in a standard format
that can be processed by the soft token on the PC.
For example, the end-user or the key issuer wants to update or
configure an existing key in the cryptomodule and requests a
replacement key container. The container may or may not include a
new key and may include new or updated key attributes such as a new
counter value in HOTP key case, a modified response format or length,
a new friendly name, etc.
2.1.2. Transport of Keys from Cryptomodule to Cryptomodule
For example, a user wants to transport a key from one cryptomodule to
another. There may be two cryptographic modules, one on a computer
one on a mobile phone, and the user wants to transport a key from the
computer to the mobile phone. The user can export the key and
related data in a standard format for input into the other
cryptomodule.
2.1.3. Transport of Keys from Cryptomodule to Server
For example, a user wants to activate and use a new key and related
data against a validation system that is not aware of this key. This
key may be embedded in the cryptomodule (e.g., SD card, USB drive)
that the user has purchased at the local electronics retailer. Along
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with the cryptomodule, the user may get the key on a CD or a floppy
in a standard format. The user can now upload via a secure online
channel or import this key and related data into the new validation
system and start using the key.
2.1.4. Server to Server Bulk Import/Export of Keys
From time to time, a key management system may be required to import
or export keys in bulk from one entity to another.
For example, instead of importing keys from a manufacturer using a
file, a validation server may download the keys using an online
protocol. The keys can be downloaded in a standard format that can
be processed by a validation system.
For example, in a variation of the above, an OTA key provisioning
gateway that provisions keys to mobile phones may obtain key material
from a key issuer using an online protocol. The keys are delivered
in a standard format that can be processed by the key provisioning
gateway and subsequently sent to the end-user's mobile phone.
2.2. Offline Use Cases
This section describes the use cases relating to offline transport of
keys from one system to another, using some form of export and import
model.
2.2.1. Server to Server Bulk Import/Export of Keys
For example, cryptomodules such as OTP authentication tokens, may
have their symmetric keys initialized during the manufacturing
process in bulk, requiring copies of the keys and algorithm data to
be loaded into the authentication system through a file on portable
media. The manufacturer provides the keys and related data in the
form of a file containing records in standard format, typically on a
CD. Note that the token manufacturer and the vendor for the
validation system may be the same or different. Some crypto modules
will allow local PIN management (the device will have a PIN pad)
hence random initial PINs set at manufacturing should be transmitted
together with the respective keys they protect.
For example, an enterprise wants to port keys and related data from
an existing validation system A into a different validation system B.
The existing validation system provides the enterprise with a
functionality that enables export of keys and related data (e.g., for
OTP authentication tokens) in a standard format. Since the OTP
tokens are in the standard format, the enterprise can import the
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token records into the new validation system B and start using the
existing tokens. Note that the vendors for the two validation
systems may be the same or different.
3. Symmetric Key Package Content Type
The symmetric key package content type is used to transfer one or
more plaintext symmetric keys from one party to another. A symmetric
key package MAY be encapsulated in one or more CMS protecting content
types. This content type must be DER encoded [X.690].
The symmetric key package content type has the following syntax:
PKCS7-CONTENT-TYPE ::= TYPE-IDENTIFIER
symmetric-key-package PKCS7-CONTENT-TYPE ::=
{ SymmetricKeyPackage IDENTIFIED BY id-ct-KP-sKeyPackage }
id-ct-KP-sKeyPackage OBJECT IDENTIFIER ::= |
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) ct(1) 25 }
SymmetricKeyPackage ::= SEQUENCE {
version KeyPkgVersion DEFAULT v1,
sKeyPkgAtts [0] SEQUENCE SIZE (1..MAX) OF Attribute OPTIONAL,
sKeys SymmetricKeys }
SymmetricKeys ::= SEQUENCE SIZE (1..MAX) OF OneSymmetricKey
OneSymmetricKey ::= SEQUENCE {
sKeyAttrs SEQUENCE SIZE (1..MAX) OF Attribute OPTIONAL,
sKey OCTET STRING OPTIONAL
-- MUST contain sKeyAttrs, sKey, or sKeyAttrs and sKey
}
KeyPkgVersion ::= INTEGER { v1(1), ... }
The SymmetricKeyPackage fields are used as follows:
- version identifies version of the symmetric key package content
structure. For this version of the specification, the default
value, v1, MUST be used.
- sKeyPkgAttrs optionally provides attributes that apply to all of
the symmetric keys in the package. If an attribute appears here it
MUST NOT also be included in sKeyAttrs.
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- sKeys contains a sequence of OneSymmetricKey values. This
structure is discussed below.
The OneSymmetricKey fields are used as follows:
- sKeyAttrs optionally provides attributes that apply to one
symmetric key. If an attribute appears here it MUST NOT also be
included in sKeyPkgAttrs.
- sKey optionally contains the key value encoded as an OCTET STRING.
The OneSymmetricKey field MUST include either sKeyAttrs, sKey, or
sKeyAttrs and sKey.
4. Security Considerations
The symmetric key package contents are not protected. This content
type can be combined with a security protocol to protect the contents
of the package.
5. IANA Considerations
None: All identifiers are already registered. Please remove this
section prior to publication as an RFC.
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[X.680] ITU-T Recommendation X.680 (2002) | ISO/IEC 8824-1:2002.
Information Technology - Abstract Syntax Notation One.
[X.681] ITU-T Recommendation X.681 (2002) | ISO/IEC 8824-2:2002.
Information Technology - Abstract Syntax Notation One: Information
Object Specification.
[X.682] ITU-T Recommendation X.682 (2002) | ISO/IEC 8824-3:2002.
Information Technology - Abstract Syntax Notation One: Constraint
Specification.
[X.683] ITU-T Recommendation X.683 (2002) | ISO/IEC 8824-4:2002.
Information Technology - Abstract Syntax Notation One:
Parameterization of ASN.1 Specifications.
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[X.690] ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002.
Information Technology - ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER).
6.2. Non-Normative References
[DSKPP] Doherty, A., Pei, M., Machani, S., and M. Nystrom, "Dynamic
Symmetric Key Provisioning Protocol (DSKPP)", work-in-progress.
[RFC3852] Housley, R., "Cryptographic Message Syntax (CMS)", RFC3852,
July 2004.
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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] through [X.683].
SymmetricKeyPackageModulev1
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
smime(16) modules(0) 33 }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL
-- IMPORTS NOTHING
PKCS7-CONTENT-TYPE ::= TYPE-IDENTIFIER
KeyPackageContentTypes PKCS7-CONTENT-TYPE ::= {
symmetric-key-package |
... -- Expect additional content types --
}
symmetric-key-package PKCS7-CONTENT-TYPE ::=
{ SymmetricKeyPackage IDENTIFIED BY id-ct-KP-sKeyPackage }
id-ct-KP-sKeyPackage OBJECT IDENTIFIER ::=
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) ct(1) 25 }
SymmetricKeyPackage ::= SEQUENCE {
version KeyPkgVersion DEFAULT v1,
sKeyPkgAttrs [0] SEQUENCE SIZE (1..MAX) OF Attribute OPTIONAL,
sKeys SymmetricKeys }
SymmetricKeys ::= SEQUENCE SIZE (1..MAX) OF OneSymmetricKey
OneSymmetricKey ::= SEQUENCE {
sKeyAttrs SEQUENCE SIZE (1..MAX) OF Attribute OPTIONAL,
sKey OCTET STRING OPTIONAL
-- MUST contain sKeyAttrs, sKey, or sKeyAttrs and sKey
}
KeyPkgVersion ::= INTEGER { v1(1), ... }
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Attribute ::= SEQUENCE {
type ATTRIBUTE.&id ({SupportedAttributes}),
values SET SIZE (1..MAX) OF ATTRIBUTE.&Type
({SupportedAttributes}{@type}) }
SupportedAttributes ATTRIBUTE ::= { ... }
ATTRIBUTE ::= CLASS {
&derivation ATTRIBUTE OPTIONAL,
&Type OPTIONAL,
-- either &Type or &derivation required
&equality-match MATCHING-RULE OPTIONAL,
&ordering-match MATCHING-RULE OPTIONAL,
&substrings-match MATCHING-RULE OPTIONAL,
&single-valued BOOLEAN DEFAULT FALSE,
&collective BOOLEAN DEFAULT FALSE,
-- operational extensions
&no-user-modification BOOLEAN DEFAULT FALSE,
&usage AttributeUsage DEFAULT userApplications,
&id OBJECT IDENTIFIER UNIQUE }
WITH SYNTAX {
[ SUBTYPE OF &derivation ]
[ WITH SYNTAX &Type ]
[ EQUALITY MATCHING RULE &equality-match ]
[ ORDERING MATCHING RULE &ordering-match ]
[ SUBSTRINGS MATCHING RULE &substrings-match ]
[ SINGLE VALUE &single-valued ]
[ COLLECTIVE &collective ]
[ NO USER MODIFICATION &no-user-modification ]
[ USAGE &usage ]
ID &id }
MATCHING-RULE ::= CLASS {
&AssertionType OPTIONAL,
&id OBJECT IDENTIFIER UNIQUE }
WITH SYNTAX {
[ SYNTAX &AssertionType ]
ID &id }
AttributeType ::= ATTRIBUTE.&id
AttributeValue ::= ATTRIBUTE.&Type
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AttributeUsage ::= ENUMERATED {
userApplications (0),
directoryOperation (1),
distributedOperation (2),
dSAOperation (3) }
END
Author's Address
Sean Turner
IECA, Inc.
3057 Nutley Street, Suite 106
Fairfax, VA 22031
USA
Email: turners@ieca.com
Russ Housley
Vigil Security, LLC
918 Spring Knoll Drive
Herndon, VA 20170
USA
EMail: housley@vigilsec.com
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