Network Working Group S. Leonard
Internet-Draft Penango, Inc.
Intended Status: Informational March 13, 2017
Expires: September 14, 2017
The PKCS #8 EncryptedPrivateKeyInfo Media Type
draft-seantek-pkcs8-encrypted-02
Abstract
This document registers the application/pkcs8-encrypted media type
for the EncryptedPrivateKeyInfo type of PKCS #8. An instance of this
media type carries a single encrypted private key, BER-encoded as a
single EncryptedPrivateKeyInfo value.
Status of this Memo
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1. Definitions
The key words "SHOULD", "SHOULD NOT", and "RECOMMENDED" in this
document are to be interpreted as described in [RFC2119].
2. Registration Application
Type name: application
Subtype name: pkcs8-encrypted
Required parameters: None.
Optional parameters:
password-mapping: The private key is encrypted with an encryption
algorithm, which could be a password-based encryption scheme (i.e.,
algorithm), as that term is used in PKCS #5 [RFC2898]. Such
algorithms take a password as input. A "password" is a secret text
value (Section 3 of PKCS #5), but for algorithmic purposes the term
"password" refers to an octet string (Section 2 of PKCS #5).
Therefore, there must be some mapping between the text value (which
might be user input) and the octet string. Section 3 of PKCS #5
recommends "that applications follow some common text encoding
rules"; it then offers, but does not recommend, ASCII and UTF-8.
This parameter specifies the charset (defined in Section 1.3 of
[RFC2978]) that a recipient SHOULD attempt first when mapping to
the octet string. This parameter is not cryptographically
protected, so recipients SHOULD NOT rely on it as the exclusive
mapping possibility.
This parameter has similar semantics as the charset parameter from
text/plain, except that it only applies to the user's input (text
value) of a password. There is no default value.
The following special values, which all begin with "*" to
distinguish them from registered charsets, are defined:
*pkcs12 = UTF-16LE with U+0000 NULL terminator: PKCS #12-style,
see [RFC7292]
*precis = PRECIS password profile, i.e., OpaqueString from
Section 4 of [RFC7613]: always UTF-8 in Normalization
Form C (NFC)
*precis-XXX = PRECIS profile as named XXX in the IANA PRECIS
Profiles Registry
*hex = hexadecimal input: the input is mapped to 0-9, A-F,
and then converted directly to octets. If there are
an odd number of hex digits, either the final digit 0
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Internet-Draft PKCS #8 Encrypted Media Type March 2017
is appended, or an error condition is raised. Compare
with Annex M.4 of IEEE 802.11-2012.
*dtmf = The characters "0"-"9", "A"-"D", "*", and "#", which
map to their corresponding ASCII codes. "A"-"D" map
to the uppercase range 0x41 - 0x44. (This is to
support restricted-input devices, i.e., telephones
and telephone-like equipment.) User input outside of
these values is either ignored, or an error condition
is raised.
Otherwise, the value of this parameter is a charset, from the IANA
Character Sets Registry [CHARREG].
This parameter is case-insensitive.
Encoding considerations: Binary.
Security considerations:
Carries a cryptographic private key. See Section 6 of [RFC5958].
EncryptedPrivateKeyInfo PKCS #8 data contains exactly one private
key. Poor password choices, weak algorithms, or improper parameter
selections (e.g., insufficient salting rounds) will make the
confidential payloads much easier to compromise.
Interoperability considerations:
PKCS #8 is a widely recognized format for private key information
on all modern cryptographic stacks. The contents are exactly one
private key (with optional key attributes), so there is no
possibility for hidden "Easter eggs" in the payload such as
unexpected certificates or miscellaneous secrets.
The encrypted variation in this registration,
EncryptedPrivateKeyInfo (Section 3, Encrypted Private Key Info, of
[RFC5958], and Section 6 of PKCS #8), is less widely used for
exchange than PKCS #12, but it is much simpler to implement.
Actually PKCS #12 incorporates the PKCS #8 types, so a PKCS #12
processor ought to be able to process PKCS #8 data by embedding the
PKCS #8 data in PKCS #12 "scaffolding".
Published specification:
PKCS #8 v1.2, November 1993 (republished as RFC 5208, May 2008);
RFC 5958, August 2010
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Internet-Draft PKCS #8 Encrypted Media Type March 2017
Applications that use this media type:
Machines, applications, browsers, Internet kiosks, and so on, that
support this standard allow a user to import, export, and exercise
a single private key.
Fragment identifier considerations: None.
Additional information:
Deprecated alias names for this type: N/A
Magic number(s): None.
File extension(s): .p8e
Macintosh file type code(s):
None. A uniform type identifier (UTI) of
"com.rsa.pkcs-8-encrypted" is RECOMMENDED.
Object Identifiers: 1.2.840.113549.1.12.10.1.2 (when in PKCS #12)
Person & email address to contact for further information:
Sean Leonard <dev+ietf@seantek.com>
Restrictions on usage: None.
Author/Change controller: Sean Leonard <dev+ietf@seantek.com>
Intended usage: COMMON
Provisional registration? No
3. IANA Considerations
IANA is asked to register the media type application/pkcs8-encrypted
in the Standards tree using the applications provided in Section 1 of
this document.
4. Security Considerations
See the registration template.
5. Normative References
[CHARREG] IANA, "Character Sets",
<http://www.iana.org/assignments/character-sets>, December
2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
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Internet-Draft PKCS #8 Encrypted Media Type March 2017
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2898] Kaliski, B., "PKCS #5: Password-Based Cryptography
Specification Version 2.0", RFC 2898, September 2000.
[RFC2978] Freed, N. and J. Postel, "IANA Charset Registration
Procedures", BCP 19, RFC 2978, October 2000.
[RFC5208] Kaliski, B., "Public-Key Cryptography Standards (PKCS) #8:
Private-Key Information Syntax Specification Version 1.2",
RFC 5208, May 2008.
[RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958, August
2010.
[RFC7292] Moriarty, K., Nystrom, S., Parkinson, S., Rusch, A., and
M. Scott, "PKCS #12: Personal Information Exchange Syntax
v1.1", RFC 7292, July 2014.
[RFC7613] Saint-Andre, P. and A. Melnikov, "Preparation,
Enforcement, and Comparison of Internationalized Strings
Representing Usernames and Passwords", RFC 7613, August
2015.
Author's Address
Sean Leonard
Penango, Inc.
5900 Wilshire Boulevard
21st Floor
Los Angeles, CA 90036
USA
EMail: dev+ietf@seantek.com
URI: http://www.penango.com/
Appendix A. Changes from -01 to -02
Updated the document as a "keep-alive". The password-mapping
parameter is still being discussed. A note was added that *precis
includes Normalization Form C (NFC).
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