OSSL_CMP_EXEC_CERTREQ(3ossl) OpenSSL OSSL_CMP_EXEC_CERTREQ(3ossl)
NAME
OSSL_CMP_exec_certreq, 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_get1_caCerts,
OSSL_CMP_get1_rootCaKeyUpdate, OSSL_CMP_get1_crlUpdate,
OSSL_CMP_get1_certReqTemplate - functions implementing CMP client
transactions
SYNOPSIS
#include <openssl/cmp.h>
X509 *OSSL_CMP_exec_certreq(OSSL_CMP_CTX *ctx, int req_type,
const OSSL_CRMF_MSG *crm);
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,
const OSSL_CRMF_MSG *crm, int *checkAfter);
int OSSL_CMP_exec_RR_ses(OSSL_CMP_CTX *ctx);
STACK_OF(OSSL_CMP_ITAV) *OSSL_CMP_exec_GENM_ses(OSSL_CMP_CTX *ctx);
int OSSL_CMP_get1_caCerts(OSSL_CMP_CTX *ctx, STACK_OF(X509) **out);
int OSSL_CMP_get1_rootCaKeyUpdate(OSSL_CMP_CTX *ctx,
const X509 *oldWithOld, X509 **newWithNew,
X509 **newWithOld, X509 **oldWithNew);
int OSSL_CMP_get1_crlUpdate(OSSL_CMP_CTX *ctx, const X509 *crlcert,
const X509_CRL *last_crl,
X509_CRL **crl);
int OSSL_CMP_get1_certReqTemplate(OSSL_CMP_CTX *ctx,
OSSL_CRMF_CERTTEMPLATE **certTemplate,
OSSL_CMP_ATAVS **keySpec);
=head1 DESCRIPTION
This is the OpenSSL main API for Certificate Management Protocol (CMP)
clients. Each of the OSSL_CMP_exec_*() functions performs a whole CMP
transaction, which is a sequence of related CMP request messages and
response messages.
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 server. In order to authenticate the server the client
typically needs a trust store. 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.
These four types of certificate enrollment are implemented as macros
calling OSSL_CMP_exec_certreq(3).
OSSL_CMP_exec_certreq(3) performs a certificate request of the type
specified by the req_type parameter, which may be IR, CR, P10CR, or KUR.
For IR, CR, and KUR, the certificate template to be used in the request
may be supplied via the crm parameter pointing to a CRMF structure.
Typically crm is NULL, then the template ingredients are taken from ctx
and need to be filled in using OSSL_CMP_CTX_set1_subjectName(3),
OSSL_CMP_CTX_set0_newPkey(3), OSSL_CMP_CTX_set1_oldCert(3), etc. For
P10CR, OSSL_CMP_CTX_set1_p10CSR(3) needs to be used instead. The
enrollment session may be blocked (with polling and sleeping in between)
until the server side can fully process and ultimately answer the
request.
OSSL_CMP_try_certreq() is an alternative to the above functions that is
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 constructed as stated above using the req_type and optional crm
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(3) 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_exec_RR_ses() requests the revocation of the certificate
specified in the ctx using the issuer DN and serial number set by
OSSL_CMP_CTX_set1_issuer(3) and OSSL_CMP_CTX_set1_serialNumber(3),
respectively, otherwise the issuer DN and serial number of the
certificate set by OSSL_CMP_CTX_set1_oldCert(3), otherwise the subject DN
and public key of the certificate signing request set by
OSSL_CMP_CTX_set1_p10CSR(3). RFC 9810 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. The revocation session may be
blocked (with polling and sleeping in between) until the server can fully
process and ultimately answer the request.
OSSL_CMP_exec_GENM_ses() sends a genm general message containing the
sequence of infoType and infoValue pairs (InfoTypeAndValue; short: ITAV)
optionally provided in the ctx using OSSL_CMP_CTX_push0_genm_ITAV(3).
The message exchange may be blocked (with polling and sleeping in
between) until the server can fully process and ultimately answer the
request. On success the function records in ctx status
OSSL_CMP_PKISTATUS_accepted and returns the list of ITAVs received in a
genp response message. This can be used, for instance, with infoType
"signKeyPairTypes" to obtain the set of signature algorithm identifiers
that the CA will certify for subject public keys. See RFC 9810 section
5.3.19 and appendix D.5 for details. Functions implementing more
specific genm/genp exchanges are described next.
OSSL_CMP_get1_caCerts() uses a genm/genp message exchange with infoType
caCerts to obtain a list of CA certificates from the CMP server
referenced by ctx. On success it assigns to *out the list of
certificates received, which must be freed by the caller. NULL output
means that no CA certificates were provided by the server.
OSSL_CMP_get1_rootCaKeyUpdate() uses a genm request message with infoType
rootCaCert to obtain from the CMP server referenced by ctx in a genp
response message with infoType rootCaKeyUpdate any update of the given
root CA certificate oldWithOld and verifies it as far as possible. See
RFC 9810 section 4.4 for details. On success it assigns to *newWithNew
the root certificate received. When the newWithOld and oldWithNew output
parameters are not NULL, it assigns to them the corresponding transition
certificates. NULL means that the respective certificate was not
provided by the server. All certificates obtained this way must be freed
by the caller.
WARNING: The newWithNew certificate is meant to be a certificate that
will be trusted. The trust placed in it cannot be stronger than the
trust placed in the oldwithold certificate if present, otherwise it
cannot be stronger than the weakest trust in any of the certificates in
the trust store of ctx.
OSSL_CMP_get1_crlUpdate() uses a genm request message with infoType
crlStatusList to obtain CRL from the CMP server referenced by ctx in a
genp response message with infoType crls. It uses last_crl and crlcert to
create a request with a status field as described for
OSSL_CMP_CRLSTATUS_create(3). On success it assigns to *crl the CRL
received. NULL means that no CRL was provided by the server. The CRL
obtained this way must be freed by the caller.
OSSL_CMP_get1_certReqTemplate() uses a genm request message with infoType
certReqTemplate to obtain a certificate request template from the CMP
server referenced by ctx. On success it assigns to *certTemplate the
certificate template received. NULL output means that no certificate
request template was provided by the server. The optional keySpec output
parameter is assigned the key specification if received, otherwise it set
to NULL. Both must be freed by the caller.
NOTES
CMP is defined in RFC 9810 (and CRMF in RFC 4211).
This CMP implementation focuses on the Lightweight CMP Profile (RFC
9483). Among other things, this implies that only commonly used CMP
message types are supported and that each CMP message may not contain
multiple certificate requests or responses.
When a client obtains from a CMP server CA certificates that it is going
to trust, for instance via the caPubs field of a certificate response or
using functions like OSSL_CMP_get1_caCerts() and
OSSL_CMP_get1_rootCaKeyUpdate(), authentication of the CMP server is
particularly critical. So special care must be taken setting up server
authentication in ctx using functions such as
OSSL_CMP_CTX_set0_trusted(3) (for certificate-based authentication) or
OSSL_CMP_CTX_set1_secretValue(3) (for MAC-based protection). If
authentication is certificate-based,
OSSL_CMP_CTX_get0_validatedSrvCert(3) should be used to obtain the server
validated certificate and perform an authorization check based on it.
RETURN VALUES
OSSL_CMP_exec_certreq(3), 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(3) 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(3) yields NULL and the output
parameter checkAfter has been used to assign the received value unless
checkAfter is NULL.
OSSL_CMP_exec_RR_ses(), OSSL_CMP_get1_caCerts(),
OSSL_CMP_get1_rootCaKeyUpdate(), OSSL_CMP_get1_crlUpdate() and
OSSL_CMP_get1_certReqTemplate() return 1 on success, 0 on error.
OSSL_CMP_exec_GENM_ses() returns NULL on error, otherwise a pointer to
the sequence of ITAV received, which may be empty. 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_CTX_free(3),
OSSL_CMP_CTX_set1_subjectName(3), OSSL_CMP_CTX_set0_newPkey(3),
OSSL_CMP_CTX_set1_p10CSR(3), OSSL_CMP_CTX_set1_oldCert(3),
OSSL_CMP_CTX_get0_newCert(3), OSSL_CMP_CTX_push0_genm_ITAV(3),
OSSL_CMP_MSG_http_perform(3), OSSL_CMP_CRLSTATUS_create(3)
HISTORY
The OpenSSL CMP functions were added in OpenSSL 3.0.
OSSL_CMP_get1_caCerts() and OSSL_CMP_get1_rootCaKeyUpdate() were added in
OpenSSL 3.2.
Support for delayed delivery of all types of response messages was added
in OpenSSL 3.3.
OSSL_CMP_get1_crlUpdate() and OSSL_CMP_get1_certReqTemplate() were added
in OpenSSL 3.4.
COPYRIGHT
Copyright 2007-2026 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>.
3.6.5 2026-09-29 OSSL_CMP_EXEC_CERTREQ(3ossl)
openssl 3.6.5 - Generated Sat Oct 3 07:23:31 CDT 2026