Updated: 2021/Apr/14

BN_security_bits(3) OpenSSL BN_security_bits(3)NAMEBN_security_bits - returns bits of security based on given numbersLIBRARYlibcrypto, -lcryptoSYNOPSIS#include <openssl/bn.h> int BN_security_bits(int L, int N);DESCRIPTIONBN_security_bits()returns the number of bits of security provided by a specific algorithm and a particular key size. The bits of security is defined in NIST SP800-57. Currently,BN_security_bits()support two types of asymmetric algorithms: the FFC (Finite Field Cryptography) and IFC (Integer Factorization Cryptography). For FFC, e.g., DSA and DH, both parametersLandNare used to decide the bits of security, whereLis the size of the public key andNis the size of the private key. For IFC, e.g., RSA, onlyLis used and it's commonly considered to be the key size (modulus).RETURNVALUESNumber of security bits.NOTESECC (Elliptic Curve Cryptography) is not covered by theBN_security_bits()function. The symmetric algorithms are not covered neither.SEEALSODH_security_bits(3),DSA_security_bits(3),RSA_security_bits(3)HISTORYTheBN_security_bits()function was added in OpenSSL 1.1.0.COPYRIGHTCopyright 2017-2019 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (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>. 1.1.1i 2019-06-09 BN_security_bits(3)