OSSL_ESS_CHECK_SIGNING_CERTS(3ossl)

💅 OSSL_ESS_CHECK_SIGNING_CERTS 💅

okay so bestie, this is from the OpenSSL manual, section 3ossl, and it's all about the Enhanced Security Services (ESS) functions. it's giving "niche but iconic" and honestly the way these three functions work together?? obsessed. let's get into it 🫶

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✨ NAME ✨

OSSL_ESS_signing_cert_new_init, OSSL_ESS_signing_cert_v2_new_init, OSSL_ESS_check_signing_certs — the Enhanced Security Services (ESS) functions 💖

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🌸 SYNOPSIS 🌸

#include <openssl/ess.h>

ESS_SIGNING_CERT *OSSL_ESS_signing_cert_new_init(const X509 *signcert,
                                                 const STACK_OF(X509) *certs,
                                                 int set_issuer_serial);
ESS_SIGNING_CERT_V2 *OSSL_ESS_signing_cert_v2_new_init(const EVP_MD *hash_alg,
                                                       const X509 *signcert,
                                                       const
                                                       STACK_OF(X509) *certs,
                                                       int set_issuer_serial);
int OSSL_ESS_check_signing_certs(const ESS_SIGNING_CERT *ss,
                                 const ESS_SIGNING_CERT_V2 *ssv2,
                                 const STACK_OF(X509) *chain,
                                 int require_signing_cert);

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🦋 DESCRIPTION 🦋

🎀 OSSL_ESS_signing_cert_new_init()

so this one generates a brand new ESS_SIGNING_CERT structure ✨ and it references the given signcert plus any given further certs — and it does that using their SHA-1 fingerprints. classic.

now, the tea ☕: if set_issuer_serial is nonzero, then also the issuer and serial number of signcert get included in the ESS_CERT_ID as the issuerSerial field. and for all members of certs, the issuerSerial field is always included. no exceptions, periodt. 👑

🧚 OSSL_ESS_signing_cert_v2_new_init()

literally the same as OSSL_ESS_signing_cert_new_init() — except it uses the given hash_alg and generates a ESS_SIGNING_CERT_V2 structure with ESS_CERT_ID_V2 elements instead. it's the upgraded version, iykyk 💅

⭐ OSSL_ESS_check_signing_certs()

this one's the vibe check 🔥 — it checks if the validation chain contains the certificates required by the identifiers given in ss and/or ssv2.

• if require_signing_cert is nonzero, then ss or ssv2 must not be NULL. like, non-negotiable.
• if both ss and ssv2 are not NULL, they are evaluated independently (main character energy for each of them, respectfully).
• the list of certificate identifiers in ss is of type ESS_CERT_ID, while the list contained in ssv2 is of type ESS_CERT_ID_V2.
• as far as these lists are present, they must be nonempty — an empty list is not the move, bestie.
• the certificate identified by their first entry must be the first element of chain, i.e. the signer certificate. 💖
• any further certificates referenced in the list must also be found in chain.
• the matching is done using the given certificate hash algorithm and value.

and in addition to the checks required by RFCs 2624 and 5035, if the issuerSerial field is included in an ESSCertID or ESSCertIDv2, it must match the certificate issuer and serial number attributes. no cap. 🎯

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🌈 NOTES 🌈

ESS has been defined in RFC 2634, which has been updated in RFC 5035 (ESS version 2) to support hash algorithms other than SHA-1. so like, glow-up behavior honestly ✨

this is used for TSP (RFC 3161) and CAdES-BES (informational RFC 5126). slay.

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💜 RETURN VALUES 💜

• OSSL_ESS_signing_cert_new_init() and OSSL_ESS_signing_cert_v2_new_init() return a pointer to the new structure, or NULL on malloc failure 😭 (we've all been there).
• OSSL_ESS_check_signing_certs() returns:
  • 1 on success 🎉
  • 0 if a required certificate cannot be found 🙈
  • -1 on other error 💀

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🔥 SEE ALSO 🔥

• TS_VERIFY_CTX_set_certs(3)
• CMS_verify(3)

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👑 HISTORY 👑

OSSL_ESS_signing_cert_new_init(), OSSL_ESS_signing_cert_v2_new_init(), and OSSL_ESS_check_signing_certs() were added in OpenSSL 3.0. they're not new new, but they're still that girl.

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🍓 COPYRIGHT 🍓

Copyright 2021-2022 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>.

okay so bestie, that's the whole thing 💖 read the License before you go off using this, fr fr — legal girlies are still girlies 🫶

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and that's a wrap! ✨ this page is from OpenSSL 3.5.0, dated 2026-09-2, and honestly? iconic. go forth and verify those signing certs, queen 👑💅🦋