NAME¶

OSSL_CMP_exec_IR_ses, OSSL_CMP_exec_CR_ses, OSSL_CMP_exec_P10CR_ses, OSSL_CMP_exec_KUR_ses, OSSL_CMP_IR, OSSL_CMP_CR, OSSL_CMP_P10CR, OSSL_CMP_KUR, OSSL_CMP_try_certreq, OSSL_CMP_exec_RR_ses, OSSL_CMP_exec_GENM_ses, OSSL_CMP_certConf_cb - functions implementing CMP client transactions

SYNOPSIS¶

 #include <openssl/cmp.h>
 X509 *OSSL_CMP_exec_IR_ses(OSSL_CMP_CTX *ctx);
 X509 *OSSL_CMP_exec_CR_ses(OSSL_CMP_CTX *ctx);
 X509 *OSSL_CMP_exec_P10CR_ses(OSSL_CMP_CTX *ctx);
 X509 *OSSL_CMP_exec_KUR_ses(OSSL_CMP_CTX *ctx);
 #define OSSL_CMP_IR
 #define OSSL_CMP_CR
 #define OSSL_CMP_P10CR
 #define OSSL_CMP_KUR
 int OSSL_CMP_try_certreq(OSSL_CMP_CTX *ctx, int req_type, int *checkAfter);
 int OSSL_CMP_certConf_cb(OSSL_CMP_CTX *ctx, X509 *cert, int fail_info,
                          const char **text);
 X509 *OSSL_CMP_exec_RR_ses(OSSL_CMP_CTX *ctx);
 STACK_OF(OSSL_CMP_ITAV) *OSSL_CMP_exec_GENM_ses(OSSL_CMP_CTX *ctx);

DESCRIPTION¶

This is the OpenSSL API for doing CMP (Certificate Management Protocol) client-server transactions, i.e., sequences of CMP requests and responses.

All functions take a populated OSSL_CMP_CTX structure as their first argument. Usually the server name, port, and path ("CMP alias") need to be set, as well as credentials the client can use for authenticating itself to the client. In order to authenticate the server the client typically needs a trust store. For performing certificate enrollment requests the certificate template needs to be sufficiently filled in, giving at least the subject name and key. The functions return their respective main results directly, while there are also accessor functions for retrieving various results and status information from the ctx. See OSSL_CMP_CTX_new(3) etc. for details.

The default conveying protocol is HTTP. Timeout values may be given per request-response pair and per transaction. See OSSL_CMP_MSG_http_perform(3) for details.

OSSL_CMP_exec_IR_ses() requests an initial certificate from the given PKI.

OSSL_CMP_exec_CR_ses() requests an additional certificate.

OSSL_CMP_exec_P10CR_ses() conveys a legacy PKCS#10 CSR requesting a certificate.

OSSL_CMP_exec_KUR_ses() obtains an updated certificate.

All these four types of certificate enrollment may be blocked by sleeping until the CAs or an intermedate PKI component can fully process and answer the request.

OSSL_CMP_try_certreq() is an alternative to these four functions that is more uniform regarding the type of the certificate request to use and more flexible regarding what to do after receiving a checkAfter value. When called for the first time (with no certificate request in progress for the given ctx) it starts a new transaction by sending a certificate request of the given type, which may be IR, CR, P10CR, or KUR as specified by the req_type parameter. Otherwise (when according to ctx a 'waiting' status has been received before) it continues polling for the pending request unless the req_type argument is < 0, which aborts the request. If the requested certificate is available the function returns 1 and the caller can use OSSL_CMP_CTX_get0_newCert() to retrieve the new certificate. If no error occurred but no certificate is available yet then OSSL_CMP_try_certreq() remembers in the CMP context that it should be retried and returns -1 after assigning the received checkAfter value via the output pointer argument (unless it is NULL). The checkAfter value indicates the number of seconds the caller should let pass before trying again. The caller is free to sleep for the given number of seconds or for some other time and/or to do anything else before retrying by calling OSSL_CMP_try_certreq() again with the same parameter values as before. OSSL_CMP_try_certreq() then polls to see whether meanwhile the requested certificate is available. If the caller decides to abort the pending certificate request and provides a negative value as the req_type argument then OSSL_CMP_try_certreq() aborts the CMP transaction by sending an error message to the server.

OSSL_CMP_certConf_cb() is a basic certificate confirmation callback validating that the new certificate can be verified with the trusted/untrusted certificates in ctx. As there is no requirement in RFC 4210 that the certificate can be validated by the client, this callback is not set by default in the context.

OSSL_CMP_exec_RR_ses() requests the revocation of the certificate specified in the ctx using OSSL_CMP_CTX_set1_oldCert(3). RFC 4210 is vague in which PKIStatus should be returned by the server. We take "accepted" and "grantedWithMods" as clear success and handle "revocationWarning" and "revocationNotification" just as warnings because CAs typically return them as an indication that the certificate was already revoked. "rejection" is a clear error. The values "waiting" and "keyUpdateWarning" make no sense for revocation and thus are treated as an error as well.

OSSL_CMP_exec_GENM_ses() sends a general message containing the sequence of infoType and infoValue pairs (InfoTypeAndValue; short: ITAV) provided in the ctx using OSSL_CMP_CTX_push0_genm_ITAV(3). It returns the list of ITAVs received in the GenRep. This can be used, for instance, to poll for CRLs or CA Key Updates. See RFC 4210 section 5.3.19 and appendix E.5 for details.

NOTES¶

CMP is defined in RFC 4210 (and CRMF in RFC 4211).

So far the CMP client implementation is limited to one request per CMP message (and consequently to at most one response component per CMP message).

RETURN VALUES¶

OSSL_CMP_exec_IR_ses(), OSSL_CMP_exec_CR_ses(), OSSL_CMP_exec_P10CR_ses(), and OSSL_CMP_exec_KUR_ses() return a pointer to the newly obtained X509 certificate on success, NULL on error. This pointer will be freed implicitly by OSSL_CMP_CTX_free() or CSSL_CMP_CTX_reinit().

OSSL_CMP_try_certreq() returns 1 if the requested certificate is available via OSSL_CMP_CTX_get0_newCert() or on successfully aborting a pending certificate request, 0 on error, and -1 in case a 'waiting' status has been received and checkAfter value is available. In the latter case OSSL_CMP_CTX_get0_newCert() yields NULL and the output parameter checkAfter has been used to assign the received value unless checkAfter is NULL.

OSSL_CMP_certConf_cb() returns fail_info if it is not equal to 0, else 0 on successful validation, or else a bit field with the OSSL_CMP_PKIFAILUREINFO_incorrectData bit set.

OSSL_CMP_exec_RR_ses() returns the pointer to the revoked certificate on success, NULL on error. This pointer will be freed implicitly by OSSL_CMP_CTX_free().

OSSL_CMP_exec_GENM_ses() returns a pointer to the received ITAV sequence on success, NULL on error. This pointer must be freed by the caller.

EXAMPLES¶

See OSSL_CMP_CTX for examples on how to prepare the context for these functions.

SEE ALSO¶

OSSL_CMP_CTX_new(3), OSSL_CMP_MSG_http_perform(3)

HISTORY¶

The OpenSSL CMP support was added in OpenSSL 3.0.

COPYRIGHT¶

Copyright 2007-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.