BN_security_bits - returns bits of security based on given numbers
 #include <openssl/bn.h>
 int BN_security_bits(int L, int N);
BN_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 parameters
  L and N are used to decide the bits of security, where L
  is the size of the public key and N is the size of the private key. For
  IFC, e.g., RSA, only L is used and it's commonly considered to be the
  key size (modulus).
ECC (Elliptic Curve Cryptography) is not covered by the
  BN_security_bits() function. The symmetric algorithms are not covered
  neither.
DH_security_bits(3), DSA_security_bits(3),
  RSA_security_bits(3)
The BN_security_bits() function was added in OpenSSL 1.1.0.
Copyright 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>.