PKCS #8 Private-Key Information Content Types

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Table of Contents

1. Introduction

The syntax for private-key information was originally described in [RFC5208], and the syntax was later revised by [RFC5958] to include the AsymmetricKeyPackage content type that supports multiple PrivateKeyInfos. This document defines PKCS #8 content types for use with one PrivateKeyInfo and EncryptedPrivateKeyInfo. These content type assignments are needed for PrivateKeyInfo and EncryptedPrivateKeyInfo to be carried in the Cryptographic Message Syntax (CMS) [RFC5652].¶

Note: A very long time ago, media types for PrivateKeyInfo and EncryptedPrivateKeyInfo were assigned as application/pkcs8 and application/pkcs8-encrypted, respectively.¶

2. Private-Key Information Content Types

This section defines a content type for private-key information and encrypted private-key information.¶

The PrivateKeyInfo content type is identified by the following object identifier:¶

id-ct-privateKeyInfo OBJECT IDENTIFIER ::= { iso(1)
 member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
 smime(16) ct(1) TBD1 }

The EncryptedPrivateKeyInfo content type is identified by the following object identifier:¶

id-ct-encrPrivateKeyInfo OBJECT IDENTIFIER ::= { iso(1)
 member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
 smime(16) ct(1) TBD2 }

3. ASN.1 Module

The ASN.1 module [X680][X690] in this section builds upon the modules in [RFC5911].¶

<CODE BEGINS>
PrivateKeyInfoContentTypes
 { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
   pkcs-9(9) smime(16) modules(0) id-mod-pkcs8ContentType(TBD0) }

DEFINITIONS IMPLICIT TAGS ::=
BEGIN

-- EXPORTS ALL

IMPORTS

CONTENT-TYPE
 FROM CryptographicMessageSyntax-2009 -- in [RFC5911]
   { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
     pkcs-9(9) smime(16) modules(0) id-mod-cms-2004-02(41) }

PrivateKeyInfo, EncryptedPrivateKeyInfo
 FROM AsymmetricKeyPackageModuleV1 -- in [RFC5958]
    { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
      pkcs-9(9) smime(16) modules(0)
      id-mod-asymmetricKeyPkgV1(50) }  ;


PrivateKeyInfoContentTypes CONTENT-TYPE ::= {
 ct-privateKeyInfo | ct-encrPrivateKeyInfo,
 ... -- Expect additional content types --  }

ct-privateKeyInfo CONTENT-TYPE ::= { PrivateKeyInfo
 IDENTIFIED BY id-ct-privateKeyInfo }

id-ct-privateKeyInfo OBJECT IDENTIFIER ::= { iso(1)
 member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
 smime(16) ct(1) TBD1 }

ct-encrPrivateKeyInfo CONTENT-TYPE ::= { EncryptedPrivateKeyInfo
 IDENTIFIED BY id-ct-encrPrivateKeyInfo }

id-ct-encrPrivateKeyInfo OBJECT IDENTIFIER ::= { iso(1)
 member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
 smime(16) ct(1) TBD2 }

END

<CODE ENDS>

4. Security Considerations

The security considerations in [RFC5958] apply here.¶

5. IANA Considerations

For the private key info content types defined in section Section 2, IANA is requested to assign an object identifier (OID) for each of the content types. The OIDs for the content types should be alloacted in the "SMI Security for S/MIME CMS Content Type" registry (1.2.840.113549.1.9.16.1) [IANA-CMS-CTS], and the description should be set to id-ct-privateKeyInfo (TDB1) and id-ct-encrPrivateKeyInfo (TBD2).¶

For the ASN.1 Module in Section 3, IANA is requested to assign an object identifier (OID) for the module identifier. The OID for the module should be allocated in the "SMI Security for S/MIME Module Identifier" registry (1.2.840.113549.1.9.16.0) [IANA-SMIME-MODS], and the Description for the new OID should be set to "id-mod-pkcs8ContentType".¶

IANA is also requested to update the application/cms entry in the "Media Types" registry to add [ RFC-to-be] to the list of RFCs where Inner Content Types (ICTs) are defined in the "Optional parameters" and the "Interoperability considerations" sections.¶

IANA is also requested to update the application/cms entry in the "Media Types" registry to add the following values to the "innerContent" list:¶

• privateKeyInfo¶

• encrPrivateKeyInfo¶

And, to update the following row in the application/cms entry's "Security considerations" section:¶

6. References

Acknowledgments

Thanks to John Gray and Deb Cooley for reviewing the document and providing comments.¶

Authors' Addresses