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 - functions to assist in
       the creation of 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

       A collection of utility functions that simplify the creation of OSSL_PARAM arrays.  The
       TYPE names are as per OSSL_PARAM_int(3).

       OSSL_PARAM_BLD_new() allocates and initialises a new OSSL_PARAM_BLD structure so that
       values can be added.  Any existing values are cleared.

       OSSL_PARAM_BLD_free() deallocates the memory allocates by OSSL_PARAM_BLD_new().

       OSSL_PARAM_BLD_to_param() converts a 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 functions return value.  OSSL_PARAM_BLD_free() can
       safely be called any time after this function is.

       OSSL_PARAM_BLD_push_TYPE() are a series of functions which will create OSSL_PARAM objects
       of the specified size and correct type for the val argument.  val is stored by value and
       an expression or auto variable can be used.

       OSSL_PARAM_BLD_push_BN() is a function that will create an OSSL_PARAM object that holds
       the specified BIGNUM bn.  If bn is marked as being securely allocated, its OSSL_PARAM
       representation will also be securely allocated.  The bn argument is stored by reference
       and the underlying BIGNUM object must exist until after OSSL_PARAM_BLD_to_param() has been
       called.

       OSSL_PARAM_BLD_push_BN_pad() is a function that will create an OSSL_PARAM object that
       holds the specified BIGNUM bn.  The object will be padded to occupy exactly sz bytes, if
       insufficient space is specified an error results.  If bn is marked as being securely
       allocated, its OSSL_PARAM representation will also be securely allocated.  The bn argument
       is stored by reference and the underlying BIGNUM object must exist until after
       OSSL_PARAM_BLD_to_param() has been called.

       OSSL_PARAM_BLD_push_utf8_string() is a function that will create 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() is a function that will create 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() is a function that will create 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.

       OSSL_PARAM_BLD_push_octet_ptr() is a function that will create 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.

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

       OSSL_PARAM_BLD_push_BN() and OSSL_PARAM_BLD_push_BN_pad() currently only support
       nonnegative BIGNUMs.  They return an error on negative BIGNUMs.

EXAMPLES

       Both examples creating an OSSL_PARAM array that contains an RSA key.  For both, the
       predefined key variables are:

           BIGNUM *p, *q;  /* both prime */
           BIGNUM *n;      /* = p * q */
           unsigned int e; /* exponent, usually 65537 */
           BIGNUM *d;      /* e^-1 */

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

SEE ALSO

       OSSL_PARAM_int(3), OSSL_PARAM(3), OSSL_PARAM_free(3)

HISTORY

       The functions described here were all added in OpenSSL 3.0.

COPYRIGHT

       Copyright 2019-2022 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>.