DH_NEW(3)

💖 DH_NEW(3) — allocate and free DH objects 💖

okay so welcome to the DH_NEW(3) page from the Library Functions Manual, bestie 🫶 this is the little corner of libcrypto where DH objects get born, get their ref count bumped, and get freed. iconic behavior, honestly.

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🎀 NAME 🎀

DH_new, DH_up_ref, DH_free — allocate and free DH objects. periodt 💅

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✨ SYNOPSIS ✨

library “libcrypto” #include <openssl/dh.h>

DH*
DH_new(void);

int
DH_up_ref(DH *dh);

void
DH_free(DH *dh);

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🌸 DESCRIPTION 🌸

The DH functions implement the Diffie-Hellman key agreement protocol. yes, that Diffie-Hellman. main character crypto energy 🔥

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. no cap, that's the whole vibe.

DH_up_ref() increments the reference count by 1. little bump, bestie ⭐

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. 🧚 and if dh is a NULL pointer, no action occurs — literally nothing happens, and that's valid 💜

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🦋 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. so if it's cooked, check ERR_get_error(3) 👀

DH_up_ref() returns 1 for success or 0 for failure. simple as that, fr fr.

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🔥 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)

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👑 HISTORY 👑

DH_new() and DH_free() first appeared in SSLeay 0.5.1 and have been available since OpenBSD 2.4. vintage but still slaying 💖

DH_up_ref() first appeared in OpenSSL 0.9.7 and has been available since OpenBSD 3.2. glow-up era ✨

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💖 Debian • June 8, 2025 • DH_NEW(3) — byeee bestie, go forth and manage those ref counts 💅