OSSL_PARAM_BLD(3ossl)

📦

version 3.5.9 · 8 versions

3.5.9 · fedora 43, fedora 44 (latest)
3.5.9 · centos-stream 9
3.5.9 · centos-stream 10
3.5.9 · alpine 3.22
3.5.9 · alpine 3.23, alpine 3.24
3.5.8 · fedora 43
3.5.1 · fedora 43
3.5.5 · fedora 44

✨ OSSL_PARAM_BLD ✨

bestie. you found the OSSL_PARAM_BLD(3ossl) page and honestly? you're about to have the easiest time of your life building OSSL_PARAM arrays. no cap. let's get into it 💖

🎀 NAME 🎀

OSSL_PARAM_BLD, OSSL_PARAM_BLD_new, OSSL_PARAM_BLD_to_param, OSSL_PARAM_BLD_free, OSSL_PARAM_BLD_push_int, OSSL_PARAM_BLD_push_uint, OSSL_PARAM_BLD_push_long, OSSL_PARAM_BLD_push_ulong, OSSL_PARAM_BLD_push_int32, OSSL_PARAM_BLD_push_uint32, OSSL_PARAM_BLD_push_int64, OSSL_PARAM_BLD_push_uint64, OSSL_PARAM_BLD_push_size_t, OSSL_PARAM_BLD_push_time_t, OSSL_PARAM_BLD_push_double, OSSL_PARAM_BLD_push_BN, OSSL_PARAM_BLD_push_BN_pad, OSSL_PARAM_BLD_push_utf8_string, OSSL_PARAM_BLD_push_utf8_ptr, OSSL_PARAM_BLD_push_octet_string, OSSL_PARAM_BLD_push_octet_ptr — a whole little squad of functions whose entire job is to help you create OSSL_PARAM arrays. 🫶

🌸 SYNOPSIS 🌸

#include <openssl/param_build.h>

typedef struct OSSL_PARAM_BLD;

OSSL_PARAM_BLD *OSSL_PARAM_BLD_new(void);
OSSL_PARAM *OSSL_PARAM_BLD_to_param(OSSL_PARAM_BLD *bld);
void OSSL_PARAM_BLD_free(OSSL_PARAM_BLD *bld);

int OSSL_PARAM_BLD_push_TYPE(OSSL_PARAM_BLD *bld, const char *key, TYPE val);

int OSSL_PARAM_BLD_push_BN(OSSL_PARAM_BLD *bld, const char *key,
                           const BIGNUM *bn);
int OSSL_PARAM_BLD_push_BN_pad(OSSL_PARAM_BLD *bld, const char *key,
                               const BIGNUM *bn, size_t sz);

int OSSL_PARAM_BLD_push_utf8_string(OSSL_PARAM_BLD *bld, const char *key,
                                    const char *buf, size_t bsize);
int OSSL_PARAM_BLD_push_utf8_ptr(OSSL_PARAM_BLD *bld, const char *key,
                                 char *buf, size_t bsize);
int OSSL_PARAM_BLD_push_octet_string(OSSL_PARAM_BLD *bld, const char *key,
                                     const void *buf, size_t bsize);
int OSSL_PARAM_BLD_push_octet_ptr(OSSL_PARAM_BLD *bld, const char *key,
                                  void *buf, size_t bsize);

💅 DESCRIPTION 💅

it's giving "utility functions that make your life so much easier". basically a lil collection of helpers that simplify creating OSSL_PARAM arrays. the TYPE names are exactly as per OSSL_PARAM_int(3). 🦋

OSSL_PARAM_BLD_new() — allocates and initialises a brand new OSSL_PARAM_BLD structure so you can start adding values to it. any existing values get cleared. fresh start, main character energy ✨
OSSL_PARAM_BLD_free() — deallocates the memory allocated by OSSL_PARAM_BLD_new(). and if the argument is NULL? nothing happens. it just chills. 💀
OSSL_PARAM_BLD_to_param() — converts your built-up OSSL_PARAM_BLD structure bld into an allocated OSSL_PARAM array. the OSSL_PARAM array and all associated storage must be freed by calling OSSL_PARAM_free() with the function's return value. and good news: OSSL_PARAM_BLD_free() can safely be called any time after this function is. 🎀
OSSL_PARAM_BLD_push_TYPE() — a whole series of functions that create OSSL_PARAM objects of the specified size and the correct type for the val argument. val is stored by value, so an expression or an auto variable can be used. easy. ✨
when TYPE denotes an integer type: signed integer types will normally get the OSSL_PARAM type OSSL_PARAM_INTEGER. when TYPE denotes an unsigned integer type, it gets the OSSL_PARAM type OSSL_PARAM_UNSIGNED_INTEGER. signed vs unsigned, bestie, they are not the same 💅
OSSL_PARAM_BLD_push_BN() — creates an OSSL_PARAM object holding the specified BIGNUM bn. when bn is zero or positive, its OSSL_PARAM type becomes OSSL_PARAM_UNSIGNED_INTEGER. when bn is negative, its OSSL_PARAM type becomes OSSL_PARAM_INTEGER. if bn is marked as being securely allocated, its OSSL_PARAM representation will also be securely allocated. the bn argument is stored by reference, so the underlying BIGNUM object must exist until after OSSL_PARAM_BLD_to_param() has been called. 👑
OSSL_PARAM_BLD_push_BN_pad() — creates an OSSL_PARAM object holding the specified BIGNUM bn. the object will be padded to occupy exactly sz bytes, and if insufficient space is specified an error results. when bn is zero or positive, its OSSL_PARAM type becomes OSSL_PARAM_UNSIGNED_INTEGER. when bn is negative, its OSSL_PARAM type becomes OSSL_PARAM_INTEGER. if bn is marked as being securely allocated, its OSSL_PARAM representation will also be securely allocated. the bn argument is stored by reference, so the underlying BIGNUM object must exist until after OSSL_PARAM_BLD_to_param() has been called. same deal, just padded 💖
OSSL_PARAM_BLD_push_utf8_string() — creates an OSSL_PARAM object that references the UTF8 string specified by buf. the length of the string bsize should not include the terminating NUL byte. if it is zero then it will be calculated. the string that buf points to is stored by reference and must remain in scope until after OSSL_PARAM_BLD_to_param() has been called. 🧚
OSSL_PARAM_BLD_push_octet_string() — creates an OSSL_PARAM object that references the octet string specified by buf and <bsize>. the memory that buf points to is stored by reference and must remain in scope until after OSSL_PARAM_BLD_to_param() has been called. 🌈
OSSL_PARAM_BLD_push_utf8_ptr() — creates an OSSL_PARAM object that references the UTF8 string specified by buf. the length of the string bsize should not include the terminating NUL byte. if it is zero then it will be calculated. the string buf points to is stored by reference and must remain in scope until the OSSL_PARAM array is freed. note that this one's scope promise goes allll the way to the free, not just to to_param() 👀
OSSL_PARAM_BLD_push_octet_ptr() — creates an OSSL_PARAM object that references the octet string specified by buf. the memory buf points to is stored by reference and must remain in scope until the OSSL_PARAM array is freed. same energy as above 💜

🦋 RETURN VALUES 🦋

OSSL_PARAM_BLD_new() returns the allocated OSSL_PARAM_BLD structure, or NULL on error.
OSSL_PARAM_BLD_to_param() returns the allocated OSSL_PARAM array, or NULL on error.
all of the OSSL_PARAM_BLD_push_TYPE functions return 1 on success and 0 on error.

⭐ NOTES ⭐

okay so this one's important, listen up bestie: OSSL_PARAM_BLD_push_BN() and OSSL_PARAM_BLD_push_BN_pad() only support nonnegative BIGNUMs. they return an error on negative BIGNUMs. to pass signed BIGNUMs, use OSSL_PARAM_BLD_push_signed_BN(). periodt. 🫶

🌟 EXAMPLES 🌟

both examples create an OSSL_PARAM array that contains an RSA key. for both, the predefined key variables are:

BIGNUM *n;           /* modulus */
unsigned int e;      /* public exponent */
BIGNUM *d;           /* private exponent */
BIGNUM *p, *q;       /* first two prime factors */
BIGNUM *dmp1, *dmq1; /* first two CRT exponents */
BIGNUM *iqmp;        /* first CRT coefficient */

💖 Example 1 💖

this example shows how to create an OSSL_PARAM array that contains an RSA private key.

OSSL_PARAM_BLD *bld = OSSL_PARAM_BLD_new();
OSSL_PARAM *params = NULL;

if (bld == NULL
    || !OSSL_PARAM_BLD_push_BN(bld, "n", n)
    || !OSSL_PARAM_BLD_push_uint(bld, "e", e)
    || !OSSL_PARAM_BLD_push_BN(bld, "d", d)
    || !OSSL_PARAM_BLD_push_BN(bld, "rsa-factor1", p)
    || !OSSL_PARAM_BLD_push_BN(bld, "rsa-factor2", q)
    || !OSSL_PARAM_BLD_push_BN(bld, "rsa-exponent1", dmp1)
    || !OSSL_PARAM_BLD_push_BN(bld, "rsa-exponent2", dmq1)
    || !OSSL_PARAM_BLD_push_BN(bld, "rsa-coefficient1", iqmp)
    || (params = OSSL_PARAM_BLD_to_param(bld)) == NULL)
    goto err;
OSSL_PARAM_BLD_free(bld);
/* Use params */
...
OSSL_PARAM_free(params);

🎀 Example 2 🎀

this example shows how to create an OSSL_PARAM array that contains an RSA public key.

OSSL_PARAM_BLD *bld = OSSL_PARAM_BLD_new();
OSSL_PARAM *params = NULL;

if (nld == NULL
    || !OSSL_PARAM_BLD_push_BN(bld, "n", n)
    || !OSSL_PARAM_BLD_push_uint(bld, "e", e)
    || (params = OSSL_PARAM_BLD_to_param(bld)) == NULL)
    goto err;
OSSL_PARAM_BLD_free(bld);
/* Use params */
...
OSSL_PARAM_free(params);

🌈 HISTORY 🌈

the functions described here were all added in OpenSSL 3.0. glow up complete ✨

💜 COPYRIGHT 💜

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 page bestie, you ate that 💅 this was OSSL_PARAM_BLD(3ossl) from the OpenSSL 3.5.9 era, dated 2026-09-29 — go forth and build your param arrays, you're literally the main character now 🌸🦋💖

📦 where this page comes from

fedora 43: openssl-devel 1:3.5.9-1.fc43 · Apache-2.0
fedora 43: openssl-devel 1:3.5.9-1.fc43 · Apache-2.0
fedora 44: openssl-devel 1:3.5.9-1.fc44 · Apache-2.0
fedora 44: openssl-devel 1:3.5.9-1.fc44 · Apache-2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-14: a language model's rewrite of the original, under its terms