crypto_ecdh_shared_secret(9)

✨ crypto_ecdh_shared_secret(9) ✨

okay so bestie, you're in the Kernel API Manual and today's main character is crypto_ecdh_shared_secret — the function that literally computes a shared secret for you. ECDH girlies rise 💅 this one's for you.

---

🎀 NAME 🎀

crypto_ecdh_shared_secret — compute a shared secret. that's it, that's the vibe ✨

---

🦋 SYNOPSIS 🦋

int crypto_ecdh_shared_secret (unsigned int curve_id , unsigned int
ndigits , const u64 *private_key , const u64 *public_key , u64 *secret
);

like, five arguments, returns an int, super chill, no cap 🫶

---

🌸 ARGUMENTS 🌸

• curve_id — the id that represents which curve you're using, iykyk. pick your curve, bestie 🎀
• ndigits — the curve's number of digits. yes, you gotta know it, it's giving "read the docs" energy but here we are 💀
• private_key — the private key of part A (that's you, main character 👑)
• public_key — the public key of your counterpart, part B 🫶
• secret — the buffer where the calculated shared secret gets stored. this is the moment, this is the slay 🌈

---

💜 NOTE 💜

genuinely important, not just vibes: it is recommended that you hash the result of crypto_ecdh_shared_secret before you use it for symmetric encryption or HMAC. like, don't raw-dog the shared secret into your cipher, bestie, hash it first 😭✨

---

⭐ RETURN ⭐

returns 0 if the shared secret was generated successfully 🎉 — and a negative value if an error occurred 💀 so like, check your return values, fr fr.

---

🧚 SEE ALSO 🧚

Kernel file ./include/crypto/internal/ecc.h — and honestly the whole ECC friend group showed up:

ecc_swap_digits(9), ecc_digits_from_bytes(9), ecc_is_key_valid(9), ecc_gen_privkey(9), ecc_make_pub_key(9), ecc_is_pubkey_valid_partial(9), ecc_is_pubkey_valid_full(9), vli_is_zero(9), vli_cmp(9), vli_sub(9), vli_from_be64(9), vli_from_le64(9), vli_mod_inv(9), vli_mod_mult_slow(9), vli_num_bits(9), ecc_alloc_point(9), ecc_free_point(9), ecc_point_is_zero(9), ecc_point_mult_shamir(9)

like, that's the whole group chat, they all ate 🔥

---

and that's the page, babes 🫶 shoutout to the source ./include/crypto/internal, dated October 2026, filed under crypto_ecdh_shared_secret(9) — iconic, no notes, periodt 💖