Network Working Group M. Myers

Network Working Group M. Myers
Request for Comments: 2511 VeriSign
Category: Standards Track C. Adams
Entrust Technologies
D. Solo
Citicorp
D. Kemp
DoD
March 1999

Internet X.509 Certificate Request Message Format

Status of this Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1999). All Rights Reserved.

1. Abstract

This document describes the Certificate Request Message Format
(CRMF). This syntax is used to convey a request for a certificate to
a Certification Authority (CA) (possibly via a Registration Authority
(RA)) for the purposes of X.509 certificate production. The request
will typically include a public key and associated registration
information.

The key words "MUST", "REQUIRED", "SHOULD", "RECOMMENDED", and "MAY"
in this document (in uppercase, as shown) are to be interpreted as
described in RFC 2119.

2. Overview

Construction of a certification request involves the following steps:

a) A CertRequest value is constructed. This value may include the
public key, all or a portion of the end-entity's (EE's) name,
other requested certificate fields, and additional control
information related to the registration process.

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RFC 2511 Internet X.509 CRMF March 1999

b) A proof of possession (of the private key corresponding to the
public key for which a certificate is being requested) value may
be calculated across the CertRequest value.

c) Additional registration information may be combined with the
proof of possession value and the CertRequest structure to form a
CertReqMessage.

d) The CertReqMessage is securely communicated to a CA. Specific
means of secure transport are beyond the scope of this
specification.

3. CertReqMessage Syntax

A certificate request message is composed of the certificate request,
an optional proof of possession field and an optional registration
information field.

CertReqMessages ::= SEQUENCE SIZE (1..MAX) OF CertReqMsg

CertReqMsg ::= SEQUENCE {
certReq CertRequest,
pop ProofOfPossession OPTIONAL,
-- content depends upon key type
regInfo SEQUENCE SIZE(1..MAX) of AttributeTypeAndValue OPTIONAL }

The proof of possession field is used to demonstrate that the entity
to be associated with the certificate is actually in possession of
the corresponding private key. This field may be calculated across
the contents of the certReq field and varies in structure and content
by public key algorithm type and operational mode.

The regInfo field SHOULD only contain supplementary information
related to the context of the certification request when such
information is required to fulfill a certification request. This
information MAY include subscriber contact information, billing
information or other ancillary information useful to fulfillment of
the certification request.

Information directly related to certificate content SHOULD be
included in the certReq content. However, inclusion of additional
certReq content by RAs may invalidate the pop field. Data therefore
intended for certificate content MAY be provided in regInfo.

See Section 8 and Appendix B for example regInfo contents.

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4. Proof of Possession (POP)

In order to prevent certain attacks and to allow a CA/RA to properly
check the validity of the binding between an end entity and a key
pair, the PKI management operations specified here make it possible
for an end entity to prove that it has possession of (i.e., is able
to use) the private key corresponding to the public key for which a
certificate is requested. A given CA/RA is free to choose how to
enforce POP (e.g., out-of-band procedural means versus the CRMF in-
band message) in its certification exchanges (i.e., this may be a
policy issue). However, it is MANDATED that CAs/RAs MUST enforce POP
by some means because there are currently many non-PKIX operational
protocols in use (various electronic mail protocols are one example)
that do not explicitly check the binding between the end entity and
the private key. Until operational protocols that do verify the
binding (for signature, encryption, and key agreement key pairs)
exist, and are ubiquitous, this binding can only be assumed to have
been verified by the CA/RA. Therefore, if the binding is not verified
by the CA/RA, certificates in the Internet Public-Key Infrastructure
end up being somewhat less meaningful.

POP is accomplished in different ways depending on the type of key
for which a certificate is requested. If a key can be used for
multiple purposes (e.g., an RSA key) then any of the methods MAY be
used.

This specification allows for cases where POP is validated by the CA,
the RA, or both. Some policies may require the CA to verify POP
during certification, in which case the RA MUST forward the end
entity's CertRequest and ProofOfPossession fields unaltered to the
CA, and as an option MAY also verify POP. If the CA is not required
by policy to verify POP, then the RA SHOULD forward the end entity's
request and proof unaltered to the CA as above. If this is not
possible (for example because the RA verifies POP by an out-of-band
method), then the RA MAY attest to the CA that the required proof has
been validated. If the CA uses an out-of-band method to verify POP
(such as physical delivery of CA-generated private keys), then the
ProofOfPossession field is not used.

4.1 Signature Keys

For signature keys, the end entity can sign a value to prove
possession of the private key.

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4.2 Key Encipherment Keys

For key encipherment keys, the end entity can provide the private key
to the CA/RA, or can be required to decrypt a value in order to prove
possession of the private key. Decrypting a value can be achieved
either directly or indirectly.

The direct method is for the RA/CA to issue a random challenge to
which an immediate response by the end entity is required.

The indirect method is to issue a certificate which is encrypted for
the end entity (and have the end entity demonstrate its ability to
decrypt this certificate in a confirmation message). This allows a CA
to issue a certificate in a form which can only be used by the
intended end entity.

4.3 Key Agreement Keys

For key agreement keys, the end entity can use any of the three
methods given in Section 5.2 for encryption keys. For the direct and
indirect methods, the end entity and the PKI management entity (i.e.,
CA or RA) must establish a shared secret key in order to prove that
the end entity has possession of the private key (i.e., in order to
decrypt the encrypted certificate or to construct the response to the
issued challenge). Note that this need not impose any restrictions
on the keys that can be certified by a given CA -- in particular, for
Diffie-Hellman keys the end entity may freely choose its algorithm
parameters -- provided that the CA can generate a short-term (or
one-time) key pair with the appropriate parameters when necessary.

The end entity may also MAC the certificate request (using a shared
secret key derived from a Diffie-Hellman computation) as a fourth
alternative for demonstrating POP. This option may be used only if
the CA already has a DH certificate that is known to the end entity
and if the EE is willing to use the CA's DH parameters.

4.4 Proof of Possession Syntax

ProofOfPossession ::= CHOICE {
raVerified [0] NULL,
-- used if the RA has already verified that the requester is in
-- possession of the private key
signature [1] POPOSigningKey,
keyEncipherment [2] POPOPrivKey,
keyAgreement [3] POPOPrivKey }

POPOSigningKey ::= SEQUENCE {
poposkInput [0] POPOSigningKeyInput OPTIONAL,

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algorithmIdentifier AlgorithmIdentifier,
signature BIT STRING }
-- The signature (using "algorithmIdentifier") is on the
-- DER-encoded value of poposkInput. NOTE: If the CertReqMsg
-- certReq CertTemplate contains the subject and publicKey values,
-- then poposkInput MUST be omitted and the signature MUST be
-- computed on the DER-encoded value of CertReqMsg certReq. If
-- the CertReqMsg certReq CertTemplate does not contain the public
-- key and subject values, then poposkInput MUST be present and
-- MUST be signed. This strategy ensures that the public key is
-- not present in both the poposkInput and CertReqMsg certReq
-- CertTemplate fields.

POPOSigningKeyInput ::= SEQUENCE {
authInfo CHOICE {
sender [0] GeneralName,
-- used only if an authenticated identity has been
-- established for the sender (e.g., a DN from a
-- previously-issued and currently-valid certificate)
publicKeyMAC PKMACValue },
-- used if no authenticated GeneralName currently exists for
-- the sender; publicKeyMAC contains a password-based MAC
-- on the DER-encoded value of publicKey
publicKey SubjectPublicKeyInfo } -- from CertTemplate

PKMACValue ::= SEQUENCE {
algId AlgorithmIdentifier,
-- the algorithm value shall be PasswordBasedMac
-- {1 2 840 113533 7 66 13}
-- the parameter value is PBMParameter
value BIT STRING }

POPOPrivKey ::= CHOICE {
thisMessage [0] BIT STRING,
-- posession is proven in this message (which contains the private
-- key itself (encrypted for the CA))
subsequentMessage [1] SubsequentMessage,
-- possession will be proven in a subsequent message
dhMAC [2] BIT STRING }
-- for keyAgreement (only), possession is proven in this message
-- (which contains a MAC (over the DER-encoded value of the
-- certReq parameter in CertReqMsg, which must include both subject
-- and publicKey) based on a key derived from the end entity's
-- private DH key and the CA's public DH key);
-- the dhMAC value MUST be calculated as per the directions given
-- in Appendix A.

SubsequentMessage ::= INTEGER {

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encrCert (0),
-- requests that resulting certificate be encrypted for the
-- end entity (following which, POP will be proven in a
-- confirmation message)
challengeResp (1) }
-- requests that CA/RA engage in challenge-response exchange with
-- end entity in order to prove private key possession

It is expected that protocols which incorporate this specification
will include the confirmation and challenge-response messages
necessary to a complete protocol.

4.4.1 Use of Password-Based MAC

The following algorithm SHALL be used when publicKeyMAC is used in
POPOSigningKeyInput to prove the authenticity of a request.

PBMParameter ::= SEQUENCE {
salt OCTET STRING,
owf AlgorithmIdentifier,
-- AlgId for a One-Way Function (SHA-1 recommended)
iterationCount INTEGER,
-- number of times the OWF is applied
mac AlgorithmIdentifier
-- the MAC AlgId (e.g., DES-MAC, Triple-DES-MAC [PKCS11],
} -- or HMAC [RFC2104, RFC2202])

The process of using PBMParameter to compute publicKeyMAC and so
authenticate the origin of a public key certification request
consists of two stages. The first stage uses shared secret
information to produce a MAC key. The second stage MACs the public
key in question using this MAC key to produce an authenticated value.

Initialization of the first stage of algorithm assumes the existence
of a shared secret distributed in a trusted fashion between CA/RA and
end-entity. The salt value is appended to the shared secret and the
one way function (owf) is applied iterationCount times, where the
salted secret is the input to the first iteration and, for each
successive iteration, the input is set to be the output of the
previous iteration, yielding a key K.

In the second stage, K and the public key are inputs to HMAC as
documented in [HMAC] to produce a value for publicKeyMAC as follows:

publicKeyMAC = Hash( K XOR opad, Hash( K XOR ipad, public key) )

where ipad and opad are defined in [RFC2104].

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The AlgorithmIdentifier for owf SHALL be SHA-1 {1 3 14 3 2 26} and
for mac SHALL be HMAC-SHA1 {1 3 6 1 5 5 8 1 2}.

5. CertRequest syntax

The CertRequest syntax consists of a request identifier, a template
of certificate content, and an optional sequence of control
information.

CertRequest ::= SEQUENCE {
certReqId INTEGER, -- ID for matching request and reply
certTemplate CertTemplate, -- Selected fields of cert to be issued
controls Controls OPTIONAL } -- Attributes affecting issuance

CertTemplate ::= SEQUENCE {
version [0] Version OPTIONAL,
serialNumber [1] INTEGER OPTIONAL,
signingAlg [2] AlgorithmIdentifier OPTIONAL,
issuer [3] Name OPTIONAL,
validity [4] OptionalValidity OPTIONAL,
subject [5] Name OPTIONAL,
publicKey [6] SubjectPublicKeyInfo OPTIONAL,
issuerUID [7] UniqueIdentifier OPTIONAL,
subjectUID [8] UniqueIdentifier OPTIONAL,
extensions [9] Extensions OPTIONAL }

OptionalValidity ::= SEQUENCE {
notBefore [0] Time OPTIONAL,
notAfter [1] Time OPTIONAL } --at least one must be present

Time ::= CHOICE {
utcTime UTCTime,
generalTime GeneralizedTime }

6. Controls Syntax

The generator of a CertRequest may include one or more control values
pertaining to the processing of the request.

Controls ::= SEQUENCE SIZE(1..MAX) OF AttributeTypeAndValue

The following controls are defined (it is recognized that this list
may expand over time): regToken; authenticator; pkiPublicationInfo;
pkiArchiveOptions; oldCertID; protocolEncrKey.

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6.1 Registration Token Control

A regToken control contains one-time information (either based on a
secret value or on knowledge) intended to be used by the CA to verify
the identity of the subject prior to issuing a certificate. Upon
receipt of a certification request containing a value for regToken,
the receiving CA verifies the information in order to confirm the
identity claimed in the certification request.

The value for regToken may be generated by the CA and provided out of
band to the subscriber, or may otherwise be available to both the CA
and the subscriber. The security of any out-of-band exchange should
be commensurate with the risk of the CA accepting an intercepted
value from someone other than the intended subscriber.

The regToken control would typically be used only for initialization
of an end entity into the PKI, whereas the authenticator control (see
Section 7.2) would typically be used for initial as well as
subsequent certification requests.

In some instances of use the value for regToken could be a text
string or a numeric quantity such as a random number. The value in
the latter case could be encoded either as a binary quantity or as a
text string representation of the binary quantity. To ensure a
uniform encoding of values regardless of the nature of the quantity,
the encoding of regToken SHALL be UTF8.

6.2 Authenticator Control.

An authenticator control contains information used in an ongoing
basis to establish a non-cryptographic check of identity in
communication with the CA. Examples include: mother's maiden name,
last four digits of social security number, or other knowledge-based
information shared with the subscriber's CA; a hash of such
information; or other information produced for this purpose. The
value for an authenticator control may be generated by the subscriber
or by the CA.

In some instances of use the value for regToken could be a text
string or a numeric quantity such as a random number. The value in
the latter case could be encoded either as a binary quantity or as a
text string representation of the binary quantity. To ensure a
uniform encoding of values regardless of the nature of the quantity,
the encoding of authenticator SHALL be UTF8.

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6.3 Publication Information Control

The pkiPublicationInfo control enables subscribers to control the
CA's publication of the certificate. It is defined by the following
syntax:

PKIPublicationInfo ::= SEQUENCE {
action INTEGER {
dontPublish (0),
pleasePublish (1) },
pubInfos SEQUENCE SIZE (1..MAX) OF SinglePubInfo OPTIONAL }

-- pubInfos MUST NOT be present if action is "dontPublish"
-- (if action is "pleasePublish" and pubInfos is omitted,
-- "dontCare" is assumed)

SinglePubInfo ::= SEQUENCE {
pubMethod INTEGER {
dontCare (0),
x500 (1),
web (2),
ldap (3) },
pubLocation GeneralName OPTIONAL }

If the dontPublish option is chosen, the requester indicates that the
PKI should not publish the certificate (this may indicate that the
requester intends to publish the certificate him/herself).

If the dontCare method is chosen, or if the PKIPublicationInfo
control is omitted from the request, the requester indicates that the
PKI MAY publish the certificate using whatever means it chooses.

If the requester wishes the certificate to appear in at least some
locations but wishes to enable the CA to make the certificate
available in other repositories, set two values of SinglePubInfo for
pubInfos: one with x500, web or ldap value and one with dontCare.

The pubLocation field, if supplied, indicates where the requester
would like the certificate to be found (note that the CHOICE within
GeneralName includes a URL and an IP address, for example).

6.4 Archive Options Control

The pkiArchiveOptions control enables subscribers to supply
information needed to establish an archive of the private key
corresponding to the public key of the certification request. It is
defined by the following syntax:

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PKIArchiveOptions ::= CHOICE {
encryptedPrivKey [0] EncryptedKey,
-- the actual value of the private key
keyGenParameters [1] KeyGenParameters,
-- parameters which allow the private key to be re-generated
archiveRemGenPrivKey [2] BOOLEAN }
-- set to TRUE if sender wishes receiver to archive the private
-- key of a key pair which the receiver generates in response to
-- this request; set to FALSE if no archival is desired.

EncryptedKey ::= CHOICE {
encryptedValue EncryptedValue,
envelopedData [0] EnvelopedData }
-- The encrypted private key MUST be placed in the envelopedData
-- encryptedContentInfo encryptedContent OCTET STRING.

EncryptedValue ::= SEQUENCE {
intendedAlg [0] AlgorithmIdentifier OPTIONAL,
-- the intended algorithm for which the value will be used
symmAlg [1] AlgorithmIdentifier OPTIONAL,
-- the symmetric algorithm used to encrypt the value
encSymmKey [2] BIT STRING OPTIONAL,
-- the (encrypted) symmetric key used to encrypt the value
keyAlg [3] AlgorithmIdentifier OPTIONAL,
-- algorithm used to encrypt the symmetric key
valueHint [4] OCTET STRING OPTIONAL,
-- a brief description or identifier of the encValue content
-- (may be meaningful only to the sending entity, and used only
-- if EncryptedValue might be re-examined by the sending entity
-- in the future)
encValue BIT STRING }

KeyGenParameters ::= OCTET STRING

An alternative to sending the key is to send the information about
how to re-generate the key using the KeyGenParameters choice (e.g.,
for many RSA implementations one could send the first random numbers
tested for primality). The actual syntax for this parameter may be
defined in a subsequent version of this document or in another
standard.

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6.5 OldCert ID Control

If present, the OldCertID control specifies the certificate to be
updated by the current certification request. The syntax of its
value is:

CertId ::= SEQUENCE {
issuer GeneralName,
serialNumber INTEGER
}

6.6 Protocol Encryption Key Control

If present, the protocolEncrKey control specifies a key the CA is to
use in encrypting a response to CertReqMessages.

This control can be used when a CA has information to send to the
subscriber that needs to be encrypted. Such information includes a
private key generated by the CA for use by the subscriber.

The encoding of protocolEncrKey SHALL be SubjectPublicKeyInfo.

7. Object Identifiers

The OID id-pkix has the value

id-pkix OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7) }

-- arc for Internet X.509 PKI protocols and their components
id-pkip OBJECT IDENTIFIER :: { id-pkix pkip(5) }

-- Registration Controls in CRMF
id-regCtrl OBJECT IDENTIFIER ::= { id-pkip regCtrl(1) }
id-regCtrl-regToken OBJECT IDENTIFIER ::= { id-regCtrl 1 }
id-regCtrl-authenticator OBJECT IDENTIFIER ::= { id-regCtrl 2 }
id-regCtrl-pkiPublicationInfo OBJECT IDENTIFIER ::= { id-regCtrl 3 }
id-regCtrl-pkiArchiveOptions OBJECT IDENTIFIER ::= { id-regCtrl 4 }
id-regCtrl-oldCertID OBJECT IDENTIFIER ::= { id-regCtrl 5 }
id-regCtrl-protocolEncrKey OBJECT IDENTIFIER ::= { id-regCtrl 6 }

-- Registration Info in CRMF
id-regInfo OBJECT IDENTIFIER ::= { id-pkip id-regInfo(2) }
id-regInfo-asciiPairs OBJECT IDENTIFIER ::= { id-regInfo 1 }
--with syntax OCTET STRING
id-regInfo-certReq OBJECT IDENTIFIER ::= { id-regInfo 2 }
--with syntax CertRequest

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8. Security Considerations

The security of CRMF delivery is reliant upon the security mechanisms
of the protocol or process used to communicate with CAs. Such
protocol or process needs to ensure the integrity, data origin
authenticity, and privacy of the message. Encryption of a CRMF is
strongly recommended if it contains subscriber-sensitive information
and if the CA has an encryption certificate that is known to the end
entity.

9. References

[HMAC] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, February 1997.

10. Acknowledgments

The authors gratefully acknowledge the contributions of Barbara Fox,
Warwick Ford, Russ Housley and John Pawling, whose review and
comments significantly clarified and improved the utility of this
specification.

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11. Authors' Addresses

Michael Myers
VeriSign, Inc.
1390 Shorebird Way
Mountain View, CA 94019

EMail: [email protected]

Carlisle Adams
Entrust Technologies
750 Heron Road, Suite E08
Ottawa, Canada, K1V 1A7

EMail: [email protected]

Dave Solo
Citicorp
666 Fifth Ave, 3rd Floor
New York, Ny 10103

EMail: [email protected]

David Kemp
National Security Agency
Suite 6734
9800 Savage Road
Fort Meade, MD 20755

EMail: [email protected]

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Appendix A. Constructing "dhMAC"

This Appendix describes the method for computing the bit string
"dhMAC" in the proof-of-possession POPOPrivKey structure for Diffie-
Hellman certificate requests.

1. The entity generates a DH public/private key-pair.

The DH parameters used to calculate the public SHOULD be those
specified in the CA's DH certificate.

From CA's DH certificate:
CApub = g^x mod p (where g and p are the established DH
parameters and x is the CA's private
DH component)
For entity E:
DH private value = y
Epub = DH public value = g^y mod p

2. The MACing process will then consist of the following steps.

a) The value of the certReq field is DER encoded, yielding a binary
string. This will be the 'text' referred to in [HMAC], the data to
which HMAC-SHA1 is applied.

b) A shared DH secret is computed, as follows,
shared secret = Kec = g^xy mod p

[This is done by the entity E as CApub^y and by the CA as Epub^x,
where CApub is retrieved from the CA's DH certificate and Epub is
retrieved from the actual certification request.]

c) A key K is derived from the shared secret Kec and the subject and
issuer names in the CA's certificate as follows:

K = SHA1(DER-encoded-subjectName | Kec | DER-encoded-issuerName)

where "|" means concatenation. If subjectName in the CA
certificate is an empty SEQUENCE then DER-encoded-subjectAltName
should be used instead; similarly, if issuerName is an empty
SEQUENCE then DER-encoded-issuerAltName should be used instead.

d) Compute HMAC-SHA1 over the data 'text' as per [RFC2104] as:
SHA1(K XOR opad, SHA1(K XOR ipad, text))

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where,
opad (outer pad) = the byte 0x36 repeated 64 times
and
ipad (inner pad) = the byte 0x5C repeated 64 times.

Namely,

(1) Append zeros to the end of K to create a 64 byte string
(e.g., if K is of length 16 bytes it will be appended with
48 zero bytes 0x00).
(2) XOR (bitwise exclusive-OR) the 64 byte string computed in
step (1) with ipad.
(3) Append the data stream 'text' to the 64 byte string
resulting from step (2).
(4) Apply SHA1 to the stream generated in step (3).
(5) XOR (bitwise exclusive-OR) the 64 byte string computed in
step (1) with opad.
(6) Append the SHA1 result from step (4) to the 64 byte string
resulting from step (5).
(7) Apply SHA1 to the stream generated in step (6) and output
the result.

Sample code is also provided in [RFC2104, RFC2202].

e) The output of (d) is encoded as a BIT STRING (the value "dhMAC").

3. The proof-of-possession process requires the CA to carry out
steps (a) through (d) and then simply compare the result of step
(d) with what it received as the "dhMAC" value. If they match then
the following can be concluded.

1) The Entity possesses the private key corresponding to the
public key in the certification request (because it needed the
private key to calculate the shared secret).

2) Only the intended CA can actually verify the request (because
the CA requires its own private key to compute the same shared
secret). This helps to protect from rogue CAs.

References

[RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: Keyed
Hashing for Message Authentication", RFC 2104, February
1997.

[RFC2202] Cheng, P. and R. Glenn, "Test Cases for HMAC-MD5 and HMAC-
SHA-1", RFC 2202, September 1997.

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Acknowledgements

The details of this Appendix were provided by Hemma Prafullchandra.

Appendix B. Use of RegInfo for Name-Value Pairs

The "value" field of the id-regInfo-utf8Pairs OCTET STRING (with
"tag" field equal to 12 and appropriate "length" field) will contain
a series of UTF8 name/value pairs.

This Appendix lists some common examples of such pairs for the
purpose of promoting interoperability among independent
implementations of this specification. It is recognized that this
list is not exhaustive and will grow with time and implementation
experience.

B.1. Example Name/Value Pairs

When regInfo is used to convey one or more name-value pairs (via id-
regInfo-utf8Pairs), the first and subsequent pairs SHALL be
structured as follows:

[name?value][%name?value]*%

This string is then encoded into an OCTET STRING and placed into the
regInfo SEQUENCE.

Reserved characters are encoded using the %xx mechanism of [RFC1738],
unless they are used for their reserved purposes.

The following table defines a recommended set of named elements.
The value in the column "Name Value" is the exact text string that
will appear in the regInfo.

Name Value
----------
version -- version of this variation of regInfo use
corp_company -- company affiliation of subscriber
org_unit -- organizational unit
mail_firstName -- personal name component
mail_middleName -- personal name component
mail_lastName -- personal name component
mail_email -- subscriber's email address
jobTitle -- job title of subscriber
employeeID -- employee identification number or string

mailStop -- mail stop
issuerName -- name of CA

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subjectName -- name of Subject
validity -- validity interval

For example:

version?1%corp_company?Acme, Inc.%org_unit?Engineering%
mail_firstName?John%mail_lastName?Smith%jobTitle?Team Leader%
[email protected]%

B.1.1. IssuerName, SubjectName and Validity Value Encoding

When they appear in id-regInfo-utf8Pairs syntax as named elements,
the encoding of values for issuerName, subjectName and validity SHALL
use the following syntax. The characters [] indicate an optional
field, ::= and | have their usual BNF meanings, and all other symbols
(except spaces which are insignificant) outside non-terminal names
are terminals. Alphabetics are case-sensitive.

issuerName ::= <names>
subjectName ::= <names>
<names> ::= <name> | <names>:<name>

<validity> ::= validity ? [<notbefore>]-[<notafter>]
<notbefore> ::= <time>
<notafter> ::= <time>

Where <time> is UTC time in the form YYYYMMDD[HH[MM[SS]]]. HH, MM,
and SS default to 00 and are omitted if at the and of value 00.

Example validity encoding:

validity?-19991231%

is a validity interval with no value for notBefore and a value of
December 31, 1999 for notAfter.

Each name comprises a single character name form identifier followed
by a name value of one or UTF8 characters. Within a name value, when
it is necessary to disambiguate a character which has formatting
significance at an outer level, the escape sequence %xx SHALL be
used, where xx represents the hex value for the encoding concerned.
The percent symbol is represented by %%.

<name> ::= X<xname>|O<oname>|E<ename>|D<dname>|U<uname>|I<iname>

Name forms and value formats are as follows:

X.500 directory name form (identifier "X"):

Myers, et. al. Standards Track [Page 17]

RFC 2511 Internet X.509 CRMF March 1999

<xname> ::= <rdns>
<rdns> ::= <rdn> | <rdns> , <rdn>
<rdn> ::= <avas>
<avas> ::= <ava> | <avas> + <ava>
<ava> ::= <attyp> = <avalue>
<attyp> ::= OID.<oid> | <stdat>

Standard attribute type <stdat> is an alphabetic attribute type
identifier from the following set:

C (country)
L (locality)
ST (state or province)
O (organization)
OU (organizational unit)
CN (common name)
STREET (street address)
E (E-mail address).

<avalue> is a name component in the form of a UTF8 character string
of 1 to 64 characters, with the restriction that in the IA5 subset of
UTF8 only the characters of ASN.1 PrintableString may be used.

Other name form (identifier "O"):
<oname> ::= <oid> , <utf8string>

E-mail address (rfc822name) name form (identifier "E"):
<ename> ::= <ia5string>

DNS name form (identifier "D"):
<dname> ::= <ia5string>

URI name form (identifier "U"):
<uname> ::= <ia5string>

IP address (identifier "I"):
<iname> ::= <oid>

For example:

issuerName?XOU=Our CA,O=Acme,C=US%
subjectName?XCN=John Smith, O=Acme, C=US, [email protected]%

References

[RFC1738] Berners-Lee, T., Masinter, L. and M. McCahill,
"Uniform Resource Locators (URL)", RFC 1738, December 1994.

Myers, et. al. Standards Track [Page 18]

RFC 2511 Internet X.509 CRMF March 1999

Appendix C. ASN.1 Structures and OIDs

PKIXCRMF {iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-crmf(5)}

CRMF DEFINITIONS IMPLICIT TAGS ::=
BEGIN

IMPORTS
-- Directory Authentication Framework (X.509)
Version, AlgorithmIdentifier, Name, Time,
SubjectPublicKeyInfo, Extensions, UniqueIdentifier
FROM PKIX1Explicit88 {iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
id-pkix1-explicit-88(1)}

-- Certificate Extensions (X.509)
GeneralName
FROM PKIX1Implicit88 {iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
id-pkix1-implicit-88(2)}

-- Cryptographic Message Syntax
EnvelopedData
FROM CryptographicMessageSyntax { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16)
modules(0) cms(1) };

CertReqMessages ::= SEQUENCE SIZE (1..MAX) OF CertReqMsg

CertReqMsg ::= SEQUENCE {
certReq CertRequest,
pop ProofOfPossession OPTIONAL,
-- content depends upon key type
regInfo SEQUENCE SIZE(1..MAX) OF AttributeTypeAndValue OPTIONAL }

CertRequest ::= SEQUENCE {
certReqId INTEGER, -- ID for matching request and reply
certTemplate CertTemplate, -- Selected fields of cert to be issued
controls Controls OPTIONAL } -- Attributes affecting issuance

CertTemplate ::= SEQUENCE {
version [0] Version OPTIONAL,
serialNumber [1] INTEGER OPTIONAL,
signingAlg [2] AlgorithmIdentifier OPTIONAL,
issuer [3] Name OPTIONAL,
validity [4] OptionalValidity OPTIONAL,
subject [5] Name OPTIONAL,

Myers, et. al. Standards Track [Page 19]

RFC 2511 Internet X.509 CRMF March 1999

publicKey [6] SubjectPublicKeyInfo OPTIONAL,
issuerUID [7] UniqueIdentifier OPTIONAL,
subjectUID [8] UniqueIdentifier OPTIONAL,
extensions [9] Extensions OPTIONAL }

OptionalValidity ::= SEQUENCE {
notBefore [0] Time OPTIONAL,
notAfter [1] Time OPTIONAL } --at least one MUST be present

Controls ::= SEQUENCE SIZE(1..MAX) OF AttributeTypeAndValue

AttributeTypeAndValue ::= SEQUENCE {
type OBJECT IDENTIFIER,
value ANY DEFINED BY type }

ProofOfPossession ::= CHOICE {
raVerified [0] NULL,
-- used if the RA has already verified that the requester is in
-- possession of the private key
signature [1] POPOSigningKey,
keyEncipherment [2] POPOPrivKey,
keyAgreement [3] POPOPrivKey }

POPOSigningKey ::= SEQUENCE {
poposkInput [0] POPOSigningKeyInput OPTIONAL,
algorithmIdentifier AlgorithmIdentifier,
signature BIT STRING }
-- The signature (using "algorithmIdentifier") is on the
-- DER-encoded value of poposkInput. NOTE: If the CertReqMsg
-- certReq CertTemplate contains the subject and publicKey values,
-- then poposkInput MUST be omitted and the signature MUST be
-- computed on the DER-encoded value of CertReqMsg certReq. If
-- the CertReqMsg certReq CertTemplate does not contain the public
-- key and subject values, then poposkInput MUST be present and
-- MUST be signed. This strategy ensures that the public key is
-- not present in both the poposkInput and CertReqMsg certReq
-- CertTemplate fields.

POPOSigningKeyInput ::= SEQUENCE {
authInfo CHOICE {
sender [0] GeneralName,
-- used only if an authenticated identity has been
-- established for the sender (e.g., a DN from a
-- previously-issued and currently-valid certificate
publicKeyMAC PKMACValue },
-- used if no authenticated GeneralName currently exists for
-- the sender; publicKeyMAC contains a password-based MAC
-- on the DER-encoded value of publicKey

Myers, et. al. Standards Track [Page 20]

RFC 2511 Internet X.509 CRMF March 1999

publicKey SubjectPublicKeyInfo } -- from CertTemplate

PKMACValue ::= SEQUENCE {
algId AlgorithmIdentifier,
-- algorithm value shall be PasswordBasedMac {1 2 840 113533 7 66 13}
-- parameter value is PBMParameter
value BIT STRING }

PBMParameter ::= SEQUENCE {
salt OCTET STRING,
owf AlgorithmIdentifier,
-- AlgId for a One-Way Function (SHA-1 recommended)
iterationCount INTEGER,
-- number of times the OWF is applied
mac AlgorithmIdentifier
-- the MAC AlgId (e.g., DES-MAC, Triple-DES-MAC [PKCS11],
} -- or HMAC [RFC2104, RFC2202])

POPOPrivKey ::= CHOICE {
thisMessage [0] BIT STRING,
-- posession is proven in this message (which contains the private
-- key itself (encrypted for the CA))
subsequentMessage [1] SubsequentMessage,
-- possession will be proven in a subsequent message
dhMAC [2] BIT STRING }
-- for keyAgreement (only), possession is proven in this message
-- (which contains a MAC (over the DER-encoded value of the
-- certReq parameter in CertReqMsg, which MUST include both subject
-- and publicKey) based on a key derived from the end entity's
-- private DH key and the CA's public DH key);
-- the dhMAC value MUST be calculated as per the directions given
-- in Appendix A.

SubsequentMessage ::= INTEGER {
encrCert (0),
-- requests that resulting certificate be encrypted for the
-- end entity (following which, POP will be proven in a
-- confirmation message)
challengeResp (1) }
-- requests that CA engage in challenge-response exchange with
-- end entity in order to prove private key possession

-- Object identifier assignments --

id-pkix OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) 7 }

-- arc for Internet X.509 PKI protocols and their components

Myers, et. al. Standards Track [Page 21]

RFC 2511 Internet X.509 CRMF March 1999

id-pkip OBJECT IDENTIFIER ::= { id-pkix 5 }

-- Registration Controls in CRMF
id-regCtrl OBJECT IDENTIFIER ::= { id-pkip 1 }

-- The following definition may be uncommented for use with
-- ASN.1 compilers which do not understand UTF8String.

-- UTF8String ::= [UNIVERSAL 12] IMPLICIT OCTET STRING

id-regCtrl-regToken OBJECT IDENTIFIER ::= { id-regCtrl 1 }
--with syntax:
RegToken ::= UTF8String

id-regCtrl-authenticator OBJECT IDENTIFIER ::= { id-regCtrl 2 }
--with syntax:
Authenticator ::= UTF8String

id-regCtrl-pkiPublicationInfo OBJECT IDENTIFIER ::= { id-regCtrl 3 }
--with syntax:

PKIPublicationInfo ::= SEQUENCE {
action INTEGER {
dontPublish (0),
pleasePublish (1) },
pubInfos SEQUENCE SIZE (1..MAX) OF SinglePubInfo OPTIONAL }
-- pubInfos MUST NOT be present if action is "dontPublish"
-- (if action is "pleasePublish" and pubInfos is omitted,
-- "dontCare" is assumed)

SinglePubInfo ::= SEQUENCE {
pubMethod INTEGER {
dontCare (0),
x500 (1),
web (2),
ldap (3) },
pubLocation GeneralName OPTIONAL }

id-regCtrl-pkiArchiveOptions OBJECT IDENTIFIER ::= { id-regCtrl 4 }
--with syntax:
PKIArchiveOptions ::= CHOICE {
encryptedPrivKey [0] EncryptedKey,
-- the actual value of the private key
keyGenParameters [1] KeyGenParameters,
-- parameters which allow the private key to be re-generated
archiveRemGenPrivKey [2] BOOLEAN }
-- set to TRUE if sender wishes receiver to archive the private
-- key of a key pair which the receiver generates in response to

Myers, et. al. Standards Track [Page 22]

RFC 2511 Internet X.509 CRMF March 1999

-- this request; set to FALSE if no archival is desired.

EncryptedKey ::= CHOICE {
encryptedValue EncryptedValue,
envelopedData [0] EnvelopedData }
-- The encrypted private key MUST be placed in the envelopedData
-- encryptedContentInfo encryptedContent OCTET STRING.

EncryptedValue ::= SEQUENCE {
intendedAlg [0] AlgorithmIdentifier OPTIONAL,
-- the intended algorithm for which the value will be used
symmAlg [1] AlgorithmIdentifier OPTIONAL,
-- the symmetric algorithm used to encrypt the value
encSymmKey [2] BIT STRING OPTIONAL,
-- the (encrypted) symmetric key used to encrypt the value
keyAlg [3] AlgorithmIdentifier OPTIONAL,
-- algorithm used to encrypt the symmetric key
valueHint [4] OCTET STRING OPTIONAL,
-- a brief description or identifier of the encValue content
-- (may be meaningful only to the sending entity, and used only
-- if EncryptedValue might be re-examined by the sending entity
-- in the future)
encValue BIT STRING }
-- the encrypted value itself

KeyGenParameters ::= OCTET STRING

id-regCtrl-oldCertID OBJECT IDENTIFIER ::= { id-regCtrl 5 }
--with syntax:
OldCertId ::= CertId

CertId ::= SEQUENCE {
issuer GeneralName,
serialNumber INTEGER }

id-regCtrl-protocolEncrKey OBJECT IDENTIFIER ::= { id-regCtrl 6 }
--with syntax:
ProtocolEncrKey ::= SubjectPublicKeyInfo

-- Registration Info in CRMF
id-regInfo OBJECT IDENTIFIER ::= { id-pkip 2 }

id-regInfo-utf8Pairs OBJECT IDENTIFIER ::= { id-regInfo 1 }
--with syntax
UTF8Pairs ::= UTF8String

id-regInfo-certReq OBJECT IDENTIFIER ::= { id-regInfo 2 }

Myers, et. al. Standards Track [Page 23]

RFC 2511 Internet X.509 CRMF March 1999

--with syntax
CertReq ::= CertRequest

END

Myers, et. al. Standards Track [Page 24]

RFC 2511 Internet X.509 CRMF March 1999

Full Copyright Statement

Copyright (C) The Internet Society (1999). All Rights Reserved.

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Myers, et. al. Standards Track [Page 25]