DH_NEW(3)                  Library Functions Manual                  DH_NEW(3)

NAME
     DH_new, DH_up_ref, DH_free - allocate and free DH objects

SYNOPSIS
     library "libcrypto"
     #include <openssl/dh.h>

     DH*
     DH_new(void);

     int
     DH_up_ref(DH *dh);

     void
     DH_free(DH *dh);

DESCRIPTION
     The DH functions implement the Diffie-Hellman key agreement protocol.

     DH_new() allocates and initializes a DH structure, setting the reference
     count to 1.  It is equivalent to DH_new_method(3) with a NULL argument.

     DH_up_ref() increments the reference count by 1.

     DH_free() decrements the reference count by 1.  If it reaches 0, it frees
     the DH structure and its components.  The values are erased before the
     memory is returned to the system.  If dh is a NULL pointer, no action
     occurs.

RETURN VALUES
     If the allocation fails, DH_new() returns NULL and sets an error code
     that can be obtained by ERR_get_error(3).  Otherwise it returns a pointer
     to the newly allocated structure.

     DH_up_ref() returns 1 for success or 0 for failure.

SEE ALSO
     BN_new(3), crypto(3), d2i_DHparams(3), DH_generate_key(3),
     DH_generate_parameters(3), DH_get0_pqg(3), DH_get_ex_new_index(3),
     DH_security_bits(3), DH_set_method(3), DH_size(3), DHparams_print(3),
     DSA_dup_DH(3), EVP_PKEY_CTX_set_dh_paramgen_prime_len(3),
     EVP_PKEY_set1_DH(3)

HISTORY
     DH_new() and DH_free() first appeared in SSLeay 0.5.1 and have been
     available since OpenBSD 2.4.

     DH_up_ref() first appeared in OpenSSL 0.9.7 and has been available since
     OpenBSD 3.2.

Linux 6.18.6-arch1-1             June 8, 2025             Linux 6.18.6-arch1-1