PKCS12_CREATE(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💅 PKCS12_CREATE(3ossl) — create a PKCS#12 structure, bestie ✨

okay so this one is from the OpenSSL fam (the 3ossl manual, iykyk) and it's literally all about making a PKCS#12 structure. it's giving secure-vault energy and honestly? we're obsessed 🎀

✨ SYNOPSIS ✨

#include <openssl/pkcs12.h>

PKCS12 *PKCS12_create(const char *pass, const char *name, EVP_PKEY *pkey,
                      X509 *cert, STACK_OF(X509) *ca,
                      int nid_key, int nid_cert, int iter, int mac_iter, int keytype);
PKCS12 *PKCS12_create_ex(const char *pass, const char *name, EVP_PKEY *pkey,
                         X509 *cert, STACK_OF(X509) *ca, int nid_key, int nid_cert,
                         int iter, int mac_iter, int keytype,
                         OSSL_LIB_CTX *ctx, const char *propq);

typedef int PKCS12_create_cb(PKCS12_SAFEBAG *bag, void *cbarg);

PKCS12 *PKCS12_create_ex2(const char *pass, const char *name, EVP_PKEY *pkey,
                          X509 *cert, STACK_OF(X509) *ca, int nid_key, int nid_cert,
                          int iter, int mac_iter, int keytype,
                          OSSL_LIB_CTX *ctx, const char *propq,
                          PKCS12_create_cb *cb, void *cbarg);

🌸 DESCRIPTION 🌸

so PKCS12_create() does exactly what it says on the tin — it creates a PKCS#12 structure 💖

let's break down the cast of characters, because there are many:

  • pass is the passphrase to use 🔑
  • name is the friendlyName to use for the supplied certificate and key
  • pkey is the private key to include in the structure, and cert is its corresponding certificate
  • ca, if not NULL, is an optional set of certificates to also include in the structure 📚

now for the algorithm params:

  • nid_key and nid_cert are the encryption algorithms that should be used for the key and certificate respectively. quick heads up though: the modes GCM, CCM, XTS, and OCB are unsupported, so don't even try it bestie 🙈
  • iter is the encryption algorithm iteration count
  • mac_iter is the MAC iteration count
  • keytype is the type of key

PKCS12_create_ex() is literally identical to PKCS12_create() but it lets you use a library context ctx and property query propq to select algorithm implementations. slay for flexibility 💅

PKCS12_create_ex2() is identical to PKCS12_create_ex() but also lets you specify a user defined callback cb of type PKCS12_create_cb, plus an optional argument cbarg that gets passed back to the callback. main character energy fr fr 👑

and about that cb — if specified, it will be called for every safebag added to the PKCS12 structure, and it allows for optional application processing on the associated safebag. like, one such use could be adding attributes to the safebag. iconic, honestly 🦋

⭐ NOTES ⭐

big news: the parameters nid_key, nid_cert, iter, mac_iter and keytype can all be set to zero and sensible defaults will be used. no cap 🧚

and what are those defaults, you ask? let me spill:

  • AES password based encryption (PBES2 with PBKDF2 and AES-256-CBC) for private keys and certificates 💜
  • the PBKDF2 and MAC key derivation iteration count of PKCS12_DEFAULT_ITER (currently 2048)
  • MAC algorithm HMAC with SHA2-256
  • the MAC key derivation algorithm used for the outer PKCS#12 structure is PKCS12KDF

now, a little plot twist 🤭 the default MAC iteration count is 1 in order to retain compatibility with old software which did not interpret MAC iteration counts. so if you don't need that compatibility, set mac_iter to PKCS12_DEFAULT_ITER. periodt.

about keytype — it adds a flag to the store private key. this is a non standard extension that is only currently interpreted by MSIE 😭 so like:

  • if set to zero, the flag is omitted
  • if set to KEY_SIG, the key can be used for signing only
  • if set to KEY_EX, it can be used for signing and encryption

this option was useful for old export grade software which could use signing only keys of arbitrary size but had restrictions on the permissible sizes of keys which could be used for encryption. ancient lore, but we keep it 💀

more little details that matter:

  • if name is NULL and cert contains an alias, then that alias will be used for the corresponding friendlyName in the PKCS12 structure instead
  • similarly, if pkey is NULL and cert contains a keyid, then that will be used for the corresponding localKeyID in the PKCS12 structure instead of the id calculated from the pkey 🔍
  • for all certificates in ca, if a certificate contains an alias or keyid, then that will be used for the corresponding friendlyName or localKeyID in the PKCS12 structure 🎀
  • either pkey, cert or both can be NULL to indicate that no key or certificate is required. in previous versions both had to be present or a fatal error was returned — so yeah, glow-up moment ✨
  • nid_key or nid_cert can be set to -1 indicating that no encryption should be used
  • mac_iter can be set to -1 and the MAC will then be omitted entirely. this is lowkey useful when running with the FIPS provider, since the PKCS12KDF is not a FIPS approvable algorithm 🚨
real talk bestie: PKCS12_create() makes assumptions regarding the encoding of the given pass phrase. see passphrase-encoding(7) for more info, ok? don't skip it 💖

and if cb is specified, then it should return 1 for success and -1 for a fatal error. a return of 0 is intended to mean to not add the bag after all. iykyk 🌈

🔥 RETURN VALUES 🔥

PKCS12_create() returns a valid PKCS12 structure, or NULL if an error occurred. simple as that 💀

🦋 CONFORMING TO 🦋

IETF RFC 7292 (https://tools.ietf.org/html/rfc7292) — go read it if you're feeling fancy 📖

💜 SEE ALSO 💜

🌈 HISTORY 🌈

  • PKCS12_create_ex() was added in OpenSSL 3.0 ⭐
  • PKCS12_create_ex2() was added in OpenSSL 3.2 ⭐

also important: the defaults for encryption algorithms, MAC algorithm, and the MAC key derivation iteration count were changed in OpenSSL 3.0 to more modern standards. we love an upgrade 💅

Copyright 2002-2024 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 whole thing, bestie 🫶 this page is from OpenSSL 3.5.0, dated 2026-09-25 — go forth and create your PKCS#12 structures with confidence ✨💖🎀

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