BN_SECURITY_BITS(3ossl)

📦
version 3.5.9 · 8 versions
, in fedora 43, fedora 44

💖 BN_SECURITY_BITS(3ossl) — the OpenSSL glow-up 💖

okay bestie, welcome to BN_SECURITY_BITS(3ossl), a lil OpenSSL page that answers the question every crypto girlie eventually asks: "how much security am I actually getting from this key??" 🦋

✨ NAME ✨

BN_security_bits — returns bits of security based on given numbers 💅

🌸 SYNOPSIS 🌸

#include <openssl/bn.h>

int BN_security_bits(int L, int N);

👑 DESCRIPTION 👑

so BN_security_bits() hands you back the number of bits of security that a specific algorithm with a particular key size is giving you. and the definition of "bits of security" here? that's straight from NIST SP800-57, no cap. 📜

right now BN_security_bits() supports two types of asymmetric algorithms:

  • FFC — Finite Field Cryptography 🌿
  • IFC — Integer Factorization Cryptography 🧩

for FFC, like DSA and DH, both parameters L and N get used to decide the bits of security:

  • L is the size of the public key
  • N is the size of the private key

for IFC, like RSA, only L is used, and honestly L is commonly considered to be the key size (the modulus). periodt. 💅

⭐ RETURN VALUES ⭐

Number of security bits. that's it, that's the whole vibe. ✨

🎀 NOTES 🎀

lowkey important stuff here, don't skip:

  • ECC (Elliptic Curve Cryptography) is not covered by the BN_security_bits() function 😭
  • the symmetric algorithms aren't covered either. neither. nope. not them. 💀
fr fr, if you came here looking for elliptic curve numbers or symmetric key numbers, this function is not the one. it said "not my job" and honestly, respect. 🫶

🦋 SEE ALSO 🦋

🌈 HISTORY 🌈

BN_security_bits() was added in OpenSSL 1.1.0. iconic debut, honestly. 🎬✨

Copyright 2017-2019 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>.

okay that's the whole page bestie, you ate that 🍓 go forth and compute your security bits responsibly 💅✨

mwah 💋 — this was OpenSSL 3.5.9, dated 2026-09-29, and yes the manual name up top was BN_SECURITY_BITS(3ossl) the whole time. slay. 👑

📦 where this page comes from