OCSP_RESP_FIND_STATUS(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💅 OCSP_resp_find_status — the OpenSSL 3ossl girlies' guide

okay so this is the 3ossl manual page for the OCSP response utility function squad, and honestly? it's giving "backstage pass to certificate status checking." let's get into it 🎀

✨ NAME ✨

The whole girl group is here — OCSP_resp_find_status, OCSP_resp_count, OCSP_resp_get0, OCSP_resp_find, OCSP_single_get0_status, OCSP_resp_get0_produced_at, OCSP_resp_get0_signature, OCSP_resp_get0_tbs_sigalg, OCSP_resp_get0_respdata, OCSP_resp_get0_certs, OCSP_resp_get0_signer, OCSP_resp_get0_id, OCSP_resp_get1_id, OCSP_check_validity, and OCSP_basic_verify — and they're all here doing OCSP response utility functions. iconic lineup, no skips 💖

🌸 SYNOPSIS 🌸

#include <openssl/ocsp.h>

int OCSP_resp_find_status(OCSP_BASICRESP *bs, OCSP_CERTID *id, int *status,
                          int *reason,
                          ASN1_GENERALIZEDTIME **revtime,
                          ASN1_GENERALIZEDTIME **thisupd,
                          ASN1_GENERALIZEDTIME **nextupd);

int OCSP_resp_count(OCSP_BASICRESP *bs);
OCSP_SINGLERESP *OCSP_resp_get0(OCSP_BASICRESP *bs, int idx);
int OCSP_resp_find(OCSP_BASICRESP *bs, OCSP_CERTID *id, int last);
int OCSP_single_get0_status(OCSP_SINGLERESP *single, int *reason,
                            ASN1_GENERALIZEDTIME **revtime,
                            ASN1_GENERALIZEDTIME **thisupd,
                            ASN1_GENERALIZEDTIME **nextupd);

const ASN1_GENERALIZEDTIME *OCSP_resp_get0_produced_at(
                            const OCSP_BASICRESP* single);

const ASN1_OCTET_STRING *OCSP_resp_get0_signature(const OCSP_BASICRESP *bs);
const X509_ALGOR *OCSP_resp_get0_tbs_sigalg(const OCSP_BASICRESP *bs);
const OCSP_RESPDATA *OCSP_resp_get0_respdata(const OCSP_BASICRESP *bs);
const STACK_OF(X509) *OCSP_resp_get0_certs(const OCSP_BASICRESP *bs);

int OCSP_resp_get0_signer(OCSP_BASICRESP *bs, X509 **signer,
                          STACK_OF(X509) *extra_certs);

int OCSP_resp_get0_id(const OCSP_BASICRESP *bs,
                      const ASN1_OCTET_STRING **pid,
                      const X509_NAME **pname);
int OCSP_resp_get1_id(const OCSP_BASICRESP *bs,
                      ASN1_OCTET_STRING **pid,
                      X509_NAME **pname);

int OCSP_check_validity(ASN1_GENERALIZEDTIME *thisupd,
                        ASN1_GENERALIZEDTIME *nextupd,
                        long sec, long maxsec);

int OCSP_basic_verify(OCSP_BASICRESP *bs, STACK_OF(X509) *certs,
                      X509_STORE *st, unsigned long flags);

🦋 DESCRIPTION 🦋

OCSP_resp_find_status() goes digging through bs looking for an OCSP response for id. found it? slay — the fields of that response get dropped into *status, *reason, *revtime, *thisupd and *nextupd. the *status value is gonna be one of V_OCSP_CERTSTATUS_GOOD, V_OCSP_CERTSTATUS_REVOKED or V_OCSP_CERTSTATUS_UNKNOWN. heads up tho: *reason and *revtime only get set if the status is V_OCSP_CERTSTATUS_REVOKED. and if *reason is set, it's the revocation reason, which will be one of:

  • OCSP_REVOKED_STATUS_NOSTATUS
  • OCSP_REVOKED_STATUS_UNSPECIFIED
  • OCSP_REVOKED_STATUS_KEYCOMPROMISE
  • OCSP_REVOKED_STATUS_CACOMPROMISE
  • OCSP_REVOKED_STATUS_AFFILIATIONCHANGED
  • OCSP_REVOKED_STATUS_SUPERSEDED
  • OCSP_REVOKED_STATUS_CESSATIONOFOPERATION
  • OCSP_REVOKED_STATUS_CERTIFICATEHOLD
  • OCSP_REVOKED_STATUS_REMOVEFROMCRL

OCSP_resp_count() just tells you how many OCSP_SINGLERESP structures are living in bs. headcount, basically 💅

OCSP_resp_get0() hands you the OCSP_SINGLERESP structure in bs at index idx, where idx runs from 0 to OCSP_resp_count(bs) - 1. zero-indexed besties, you know the drill.

OCSP_resp_find() searches bs for id and gives you back the index of the first matching entry after last — or starting from the beginning if last is -1.

OCSP_single_get0_status() extracts the fields of single into *reason, *revtime, *thisupd and *nextupd.

OCSP_resp_get0_produced_at() extracts the producedAt field from the single response bs. timestamp tea ☕

OCSP_resp_get0_signature() returns the signature from bs.

OCSP_resp_get0_tbs_sigalg() returns the signatureAlgorithm from bs.

OCSP_resp_get0_respdata() returns the tbsResponseData from bs.

OCSP_resp_get0_certs() returns any certificates included in bs.

OCSP_resp_get0_signer() tries to retrieve the certificate that directly signed bs. plot twist: the OCSP protocol does not require that this certificate is included in the certs field of the response 😭 so if you already know (via some out-of-band mechanism) which certificates might have signed the response, you can pass them in through extra_certs. very "bring your own proof" of it.

OCSP_resp_get0_id() gets the responder id of bs. if the responder ID is a name, then <*pname> is set to the name and *pid is set to NULL. if the responder ID is by key ID, then *pid is set to the key ID and *pname is set to NULL. one or the other, never both, we don't do ambiguity here ✨

OCSP_resp_get1_id() is the same as OCSP_resp_get0_id() but it leaves ownership of *pid and *pname with the caller — and you're responsible for freeing them unless the function returns 0. so like, you own it now, congrats, also don't forget to clean up 🫶

OCSP_check_validity() checks the validity of its thisupd and nextupd arguments, which you'd typically get from OCSP_resp_find_status() or OCSP_single_get0_status(). if sec is nonzero it tells you how many seconds of leeway should be allowed in the check. if maxsec is positive it tells you the maximum age of thisupd, in seconds.

OCSP_basic_verify() is the big one — it checks that the basic response message bs is correctly signed and that the signer certificate can be validated. it takes st as the trusted store and certs as a set of untrusted intermediate certificates. here's the whole journey:

  1. First it tries to find the signer certificate of the response in certs.
  2. Then it searches the certificates the responder may have included in bs — unless flags contains OCSP_NOINTERN.
  3. It fails if the signer certificate cannot be found.
  4. Next, unless flags contains OCSP_NOSIGS, the function checks the signature of bs and fails on error.
  5. Then the function already returns success if flags contains OCSP_NOVERIFY, or if the signer certificate was found in certs and flags contains OCSP_TRUSTOTHER.
  6. Otherwise the function continues by validating the signer certificate.
  7. If flags contains OCSP_PARTIAL_CHAIN it takes intermediate CA certificates in st as trust anchors. for more details, see the description of X509_V_FLAG_PARTIAL_CHAIN in "VERIFICATION FLAGS" in X509_VERIFY_PARAM_set_flags(3).
  8. If flags contains OCSP_NOCHAIN it ignores all certificates in certs and in bs; else it takes them as untrusted intermediate CA certificates and uses them for constructing the validation path for the signer certificate.
  9. Certificate revocation status checks using CRLs is disabled during path validation if the signer certificate contains the id-pkix-ocsp-no-check extension.
  10. After successful path validation the function returns success if the OCSP_NOCHECKS flag is set.
  11. Otherwise it verifies that the signer certificate meets the OCSP issuer criteria, including potential delegation.
  12. If this does not succeed and the OCSP_NOEXPLICIT flag is not set, the function checks for explicit trust for OCSP signing in the root CA certificate.

that's a whole saga, honestly 💀 but it all makes sense, i promise.

🔥 RETURN VALUES 🔥

  • OCSP_resp_find_status() returns 1 if id is found in bs and 0 otherwise.
  • OCSP_resp_count() returns the total number of OCSP_SINGLERESP fields in bs or -1 on error.
  • OCSP_resp_get0() returns a pointer to an OCSP_SINGLERESP structure or NULL on error, such as idx being out of range.
  • OCSP_resp_find() returns the index of id in bs (which may be 0) or -1 on error, such as when id was not found.
  • OCSP_single_get0_status() returns the status of single or -1 if an error occurred.
  • OCSP_resp_get0_produced_at() returns the producedAt field from bs.
  • OCSP_resp_get0_signature() returns the signature from bs.
  • OCSP_resp_get0_tbs_sigalg() returns the signatureAlgorithm field from bs.
  • OCSP_resp_get0_respdata() returns the tbsResponseData field from bs.
  • OCSP_resp_get0_certs() returns any certificates included in bs.
  • OCSP_resp_get0_signer() returns 1 if the signing certificate was located, or 0 if not found or on error.
  • OCSP_resp_get0_id() and OCSP_resp_get1_id() return 1 on success, 0 on failure.
  • OCSP_check_validity() returns 1 if thisupd and nextupd are valid time values and the current time + sec is not before thisupd and, if maxsec >= 0, the current time - maxsec is not past nextupd. otherwise it returns 0 to indicate an error.
  • OCSP_basic_verify() returns 1 on success, 0 on verification not successful, or -1 on a fatal error such as malloc failure.
ngl, the -1 on OCSP_basic_verify() is the "something actually broke" signal, not just "the answer was no." don't mix them up bestie 🙈

💜 NOTES 💜

Applications will typically call OCSP_resp_find_status() with the certificate ID of interest, then check its validity using OCSP_check_validity(). after that they can take appropriate action based on the status of the certificate. the classic two-step 💅

An OCSP response for a certificate contains thisUpdate and nextUpdate fields. normally the current time should be between these two values. to account for clock skew, the maxsec field can be set to nonzero in OCSP_check_validity(). also real talk: some responders do not set the nextUpdate field, and this would otherwise mean an ancient response would be considered valid 😭 — the maxsec parameter to OCSP_check_validity() can be used to limit the permitted age of responses. use it, protect yourself.

The values written to *revtime, *thisupd and *nextupd by OCSP_resp_find_status() and OCSP_single_get0_status() are internal pointers which MUST NOT be freed up by the calling application. i cannot stress this enough — do not free them. any or all of these parameters can be set to NULL if their value is not required, which is honestly so convenient of them.

🌈 SEE ALSO 🌈

crypto(7), OCSP_cert_to_id(3), OCSP_request_add1_nonce(3), OCSP_REQUEST_new(3), OCSP_response_status(3), OCSP_sendreq_new(3), X509_VERIFY_PARAM_set_flags(3)

Copyright 2015-2022 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>.

and that's the page bestie! 💖 this was OpenSSL 3.5.0, dated 2026-09-25 — OCSP_resp_find_status(3ossl), going out with a slay. 🦋✨

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