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SEC LAMPS Working Group Public Key Infrastructure Cryptographic Message Syntax Certificate Management Compliance This document provides a set of compliance statements about the CMC (Certificate Management over CMS) enrollment protocol. The ASN.1 structures and the transport mechanisms for the CMC enrollment protocol are covered in other documents. This document provides the information needed to make a compliant version of CMC. This document obsoletes RFCs 5274 and 6402. Status information for this document may be found at . Discussion of this document takes place on the WG LAMPS mailing list (), which is archived at . Subscribe at . Source for this draft and an issue tracker can be found at .

Introduction The CMC (Certificate Management over CMS) protocol is designed in terms of a client/server relationship. In the simplest case, the client is the requestor of the certificate (i.e., the End Entity (EE)) and the server is the issuer of the certificate (i.e., the Certification Authority (CA)). The introduction of a Registration Authority (RA) into the set of agents complicates the picture only slightly. The RA becomes the server with respect to the certificate requestor, and it becomes the client with respect to the certificate issuer. Any number of RAs can be inserted into the picture in this manner. The RAs may serve specialized purposes that are not currently covered by this document. One such purpose would be a Key Escrow agent. As such, all certificate requests for encryption keys would be directed through this RA and it would take appropriate action to do the key archival. Key recovery requests could be defined in the CMC methodology allowing for the Key Escrow agent to perform that operation acting as the final server in the chain of agents. If there are multiple RAs in the system, it is considered normal that not all RAs will see all certificate requests. The routing between the RAs may be dependent on the content of the certificate requests involved. This document is divided into six sections, each section specifying the requirements that are specific to a class of agents in the CMC model. These are 1) All agents, 2) all servers, 3) all clients, 4) all End-Entities, 5) all Registration Entities, 6) all Certificate Authorities. This document obsoletes and .

Terminology There are several different terms, abbreviations, and acronyms used in this document that we define here for convenience and consistency of usage:

End-Entity (EE):

Refers to the entity that owns a key pair and for whom a certificate is issued.

Registration Authority (RA) or Local RA (LRA):

Refers to an entity that acts as an intermediary between the EE and the CA. Multiple RAs can exist between the End-Entity and the Certification Authority. RAs may perform additional services such as key generation or key archival. This document uses the term RA for both RA and LRA.

Certification Authority (CA):

Refers to the entity that issues certificates.

Client:

Refers to an entity that creates a PKI Request. In this document, both RAs and EEs can be clients.

Server:

Refers to the entities that process PKI Requests and create PKI Responses. In this document both CAs and RAs can be servers.

PKCS #10:

Refers to the Public Key Cryptography Standard #10 , which defines a certification request syntax.

CRMF:

Refers to the Certificate Request Message Format RFC . CMC uses this certification request syntax defined in this document as part of the protocol.

CMS:

Refers to the Cryptographic Message Syntax RFC . This document provides for basic cryptographic services including encryption and signing with and without key management.

PKI Request/Response:

Refers to the requests/responses described in this document. PKI Requests include certification requests, revocation requests, etc. PKI Responses include certs-only messages, failure messages, etc.

Proof-of-Identity:

Refers to the client proving they are who they say that they are to the server.

Proof-of-Possession (POP):

Refers to a value that can be used to prove that the private key corresponding to a public key is in the possession and can be used by an end-entity.

Transport wrapper:

Refers to the outermost CMS wrapping layer.

Requirements Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Changes since RFC 5274 and 6402 TODO for -01: Update TLS text Update SHA-1 text Merge requirements terminology and terminology sections Make sure section count in s1 is correct Update references to 5272bis and 5273bis -00 version changes: Added "Changes Since 5274 and 6402" section Updated references Merged text Updated and moved Acknowledgments

Requirements for All Entities All and compliance statements MUST be adhered to unless specifically stated otherwise in this document. All entities MUST support Full PKI Requests, Simple PKI Responses, and Full PKI Responses. Servers SHOULD support Simple PKI Requests. All entities MUST support the use of the CRMF syntax for certification requests. Support for the PKCS #10 syntax for certification requests SHOULD be implemented by servers. The extendedFailInfo field SHOULD NOT be populated in the CMCStatusInfoV2 object; the failInfo field SHOULD be used to relay this information. If the extendedFailInfo field is used, it is suggested that an additional CMCStatusInfoV2 item exist for the same body part with a failInfo field. All entities MUST implement the HTTP transport mechanism as defined in . Other transport mechanisms MAY be implemented.

Cryptographic Algorithm Requirements All entities MUST verify DSA-SHA1 and RSA-SHA1 signatures in SignedData (see ). Entities MAY verify other signature algorithms. It is strongly suggested that RSA-PSS with SHA-1 be verified (see ). It is strongly suggested that SHA-256 using RSA and RSA-PSS be verified (see ). All entities MUST generate either DSA-SHA1 or RSA-SHA1 signatures for SignedData (see ). Other signatures algorithms MAY be used for generation. All entities MUST support Advanced Encryption Standard (AES) as the content encryption algorithm for EnvelopedData (see ). Other content encryption algorithms MAY be implemented. All entities MUST support RSA as a key transport algorithm for EnvelopedData (see ). All entities SHOULD support RSA-OAEP (see ) as a key transport algorithm. Other key transport algorithms MAY be implemented. If an entity supports key agreement for EnvelopedData, it MUST support Diffie-Hellman (see ). If an entity supports PasswordRecipientInfo for EnvelopedData or AuthenticatedData, it MUST support PBKDF2 for key derivation algorithms. It MUST support AES key wrap (see as the key encryption algorithm. If AuthenticatedData is supported, PasswordRecipientInfo MUST be supported. Algorithm requirements for the Identity Proof Version 2 control are: SHA-1 MUST be implemented for hashAlgId. SHA-256 SHOULD be implemented for hashAlgId. HMAC-SHA1 MUST be implemented for macAlgId. HMAC-SHA256 SHOULD be implemented for macAlgId. Algorithm requirements for the Pop Link Witness Version 2 control are: SHA-1 MUST be implemented for keyGenAlgorithm. SHA-256 SHOULD be implemented for keyGenAlgorithm. PBKDF2 MAY be implemented for keyGenAlgorithm. HMAC-SHA1 MUST be implemented for macAlgorithm. HMAC-SHA256 SHOULD be implemented for macAlgorithm. Algorithm requirements for the Encrypted POP and Decrypted POP controls are: SHA-1 MUST be implemented for witnessAlgID. SHA-256 SHOULD be implemented for witnessAlgID. HMAC-SHA1 MUST be implemented for thePOPAlgID. HMAC-SHA256 SHOULD be implemented for thePOPAlgID. Algorithm requirements for Publish Trust Anchors control are: SHA-1 MUST be implemented for hashAlgorithm. SHA-256 SHOULD be implemented for hashAlgorithm. If an EE generates DH keys for certification, it MUST support . EEs MAY support . CAs and RAs that do POP verification MUST support and SHOULD support . EEs that need to use a signature algorithm for keys that cannot produce a signature MUST support Appendix C of and MUST support the Encrypted/Decrypted POP controls. CAs and RAs that do POP verification MUST support this signature algorithm and MUST support the Encrypted/Decrypted POP controls.

Controls The following table lists the name and level of support required for each control. Control EE RA CA Extended CMC Status Info MUST MUST MUST CMC Status Info SHOULD SHOULD SHOULD Identity Proof Version 2 MUST MUST MUST Identity Proof SHOULD SHOULD SHOULD Identification MUST MUST MUST POP Link Random MUST MUST MUST POP Link Witness Version 2 MUST MUST MUST POP Link Witness SHOULD MUST MUST Data Return MUST MUST MUST Modify Cert Request N/A MUST (2) Add Extensions N/A MAY (1) Transaction ID MUST MUST MUST Sender Nonce MUST MUST MUST Recipient Nonce MUST MUST MUST Encrypted POP (4) (5) SHOULD Decrypted POP (4) (5) SHOULD RA POP Witness N/A SHOULD (1) Get Certificate optional optional optional Get CRL optional optional optional Revocation Request SHOULD SHOULD MUST Registration Info SHOULD SHOULD SHOULD Response Information SHOULD SHOULD SHOULD Query Pending MUST MUST MUST Confirm Cert. Acceptance MUST MUST MUST Publish Trust Anchors (3) (3) (3) Authenticate Data (3) (3) (3) Batch Request N/A MUST (2) Batch Responses N/A MUST (2) Publication Information optional optional optional Control Processed N/A MUST (2) RA Identity Proof Witness N/A MUST (2) Response Body (6) (6) N/A. Notes: CAs SHOULD implement this control if designed to work with RAs. CAs MUST implement this control if designed to work with RAs. Implementation is optional for these controls. We strongly suggest that they be implemented in order to populate client trust anchors. EEs only need to implement this if (a) they support key agreement algorithms or (b) they need to operate in environments where the hardware keys cannot provide POP. RAs SHOULD implement this if they implement RA POP Witness. EE's SHOULD implement if designed to work with RAs and MUST implement if intended to be used in environments where RAs are used for identity validation or key generation. RAs SHOULD implement and validate responses for consistency. Strong consideration should be given to implementing the Authenticate Data and Publish Trust Anchors controls as this gives a simple method for distributing trust anchors into clients without user intervention.

CRMF Feature Requirements The following additional restrictions are placed on CRMF features: The registration control tokens id-regCtrl-regToken and id-regCtrl- authToken MUST NOT be used. No specific CMC feature is used to replace these items, but generally the CMC controls identification and identityProof will perform the same service and are more specifically defined. The control token id-regCtrl-pkiArchiveOptions SHOULD NOT be supported. An alternative method is under development to provide this functionality. The behavior of id-regCtrl-oldCertID is not presently used. It is replaced by issuing the new certificate and using the id-cmc- publishCert to remove the old certificate from publication. This operation would not normally be accompanied by an immediate revocation of the old certificate; however, that can be accomplished by the id-cmc-revokeRequest control. The id-regCtrl-protocolEncrKey is not used.

Requirements for Clients There are no additional requirements.

Requirements for Servers There are no additional requirements.

Requirements for EEs If an entity implements Diffie-Hellman, it MUST implement either the DH-POP Proof-of-Possession as defined in or the challenge-response POP controls id-cmc-encryptedPOP and id-cmc- decryptedPOP.

Requirements for RAs RAs SHOULD be able to do delegated POP. RAs implementing this feature MUST implement the id-cmc-lraPOPWitness control. All RAs MUST implement the promotion of the id-aa-cmc-unsignedData as covered in .

Requirements for CAs Providing for CAs to work in an environment with RAs is strongly suggested. Implementation of such support is strongly suggested as this permits the delegation of substantial administrative interaction onto an RA rather than at the CA. CAs MUST perform at least minimal checks on all public keys before issuing a certificate. At a minimum, a check for syntax would occur with the POP operation. Additionally, CAs SHOULD perform simple checks for known bad keys such as small subgroups for DSA-SHA1 and DH keys or known bad exponents for RSA keys. CAs MUST enforce POP checking before issuing any certificate. CAs MAY delegate the POP operation to an RA for those cases where 1) a challenge/response message pair must be used, 2) an RA performs escrow of a key and checks for POP in that manner, or 3) an unusual algorithm is used and that validation is done at the RA. CAs SHOULD implement both the DH-POP Proof-of-Possession as defined in and the challenge-response POP controls id- cmc-encryptedPOP and id-cmc-decryptedPOP.

Security Considerations This document uses and as building blocks to this document. The security sections of those two documents are included by reference. Knowledge of how an entity is expected to operate is vital in determining which sections of requirements are applicable to that entity. Care needs to be taken in determining which sections apply and fully implementing the necessary code. Cryptographic algorithms have and will be broken or weakened. Implementers and users need to check that the cryptographic algorithms listed in this document make sense from a security level. The IETF from time to time may issue documents dealing with the current state of the art. Two examples of such documents are and .

This document defines the base syntax for CMC, a Certificate Management protocol using the Cryptographic Message Syntax (CMS). This protocol addresses two immediate needs within the Internet Public Key Infrastructure (PKI) community: 1. The need for an interface to public key certification products and services based on CMS and PKCS #10 (Public Key Cryptography Standard), and 2. The need for a PKI enrollment protocol for encryption only keys due to algorithm or hardware design. CMC also requires the use of the transport document and the requirements usage document along with this document for a full definition. [STANDARDS-TRACK] This document defines a number of transport mechanisms that are used to move CMC (Certificate Management over CMS (Cryptographic Message Syntax)) messages. The transport mechanisms described in this document are HTTP, file, mail, and TCP. [STANDARDS-TRACK] This document describes the Cryptographic Message Syntax (CMS). This syntax is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. [STANDARDS-TRACK] This document specifies the conventions for using the Advanced Encryption Standard (AES) algorithm for encryption with the Cryptographic Message Syntax (CMS). [STANDARDS-TRACK] This document standardizes one particular Diffie-Hellman variant, based on the ANSI X9.42 draft, developed by the ANSI X9F1 working group. [STANDARDS-TRACK] This document describes the Certificate Request Message Format (CRMF) syntax and semantics. 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 the associated registration information. This document does not define a certificate request protocol. [STANDARDS-TRACK] This document describes the conventions for using the RSAES-OAEP key transport algorithm with the Cryptographic Message Syntax (CMS). The CMS specifies the enveloped-data content type, which consists of an encrypted content and encrypted content-encryption keys for one or more recipients. The RSAES-OAEP key transport algorithm can be used to encrypt content-encryption keys for intended recipients. [STANDARDS-TRACK] This document specifies the conventions for using the RSASSA-PSS (RSA Probabilistic Signature Scheme) digital signature algorithm with the Cryptographic Message Syntax (CMS). [STANDARDS-TRACK] This document describes two methods for producing an integrity check value from a Diffie-Hellman key pair and one method for producing an integrity check value from an Elliptic Curve key pair. This behavior is needed for such operations as creating the signature of a Public-Key Cryptography Standards (PKCS) #10 Certification Request. These algorithms are designed to provide a Proof-of-Possession of the private key and not to be a general purpose signing algorithm. This document obsoletes RFC 2875. This document supplements RFC 3279. It describes the conventions for using the RSA Probabilistic Signature Scheme (RSASSA-PSS) signature algorithm, the RSA Encryption Scheme - Optimal Asymmetric Encryption Padding (RSAES-OAEP) key transport algorithm and additional one-way hash functions with the Public-Key Cryptography Standards (PKCS) #1 version 1.5 signature algorithm in the Internet X.509 Public Key Infrastructure (PKI). Encoding formats, algorithm identifiers, and parameter formats are specified. [STANDARDS-TRACK] This document provides recommendations for the implementation of password-based cryptography, covering key derivation functions, encryption schemes, message-authentication schemes, and ASN.1 syntax identifying the techniques. This memo provides information for the Internet community. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This memo represents a republication of PKCS #10 v1.7 from RSA Laboratories' Public-Key Cryptography Standards (PKCS) series, and change control is retained within the PKCS process. The body of this document, except for the security considerations section, is taken directly from the PKCS #9 v2.0 or the PKCS #10 v1.7 document. This memo provides information for the Internet community. This document will describe the situations relevant to implementations of S/MIME version 3 in which protection is necessary and the methods that can be used to prevent these attacks. This memo provides information for the Internet community. Recent announcements of better-than-expected collision attacks in popular hash algorithms have caused some people to question whether common Internet protocols need to be changed, and if so, how. This document summarizes the use of hashes in many protocols, discusses how the collision attacks affect and do not affect the protocols, shows how to thwart known attacks on digital certificates, and discusses future directions for protocol designers. This memo provides information for the Internet community. This document provides a set of compliance statements about the CMC (Certificate Management over CMS) enrollment protocol. The ASN.1 structures and the transport mechanisms for the CMC enrollment protocol are covered in other documents. This document provides the information needed to make a compliant version of CMC. [STANDARDS-TRACK] This document contains a set of updates to the base syntax for CMC, a Certificate Management protocol using the Cryptographic Message Syntax (CMS). This document updates RFC 5272, RFC 5273, and RFC 5274. The new items in this document are: new controls for future work in doing server side key generation, definition of a Subject Information Access value to identify CMC servers, and the registration of a port number for TCP/IP for the CMC service to run on. [STANDARDS-TRACK]

Acknowledgements Obviously, the authors of this version of the document would like to thank Jim Schaad and Michael Myers for their work on the previous version of this document. The acknowledgment from the previous version of this document follows: The authors and the PKIX Working Group are grateful for the participation of Xiaoyi Liu and Jeff Weinstein in helping to author the original versions of this document. The authors would like to thank Brian LaMacchia for his work in developing and writing up many of the concepts presented in this document. The authors would also like to thank Alex Deacon and Barb Fox for their contributions.

Contributors August Cellars

TraceRoute Security, Inc.