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diff --git a/doc/man3/BN_security_bits.pod b/doc/man3/BN_security_bits.pod
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+=pod
+
+=head1 NAME
+
+BN_security_bits - returns bits of security based on given numbers
+
+=head1 SYNOPSIS
+
+ #include <openssl/bn.h>
+
+ int BN_security_bits(int L, int N);
+
+=head1 DESCRIPTION
+
+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 B<L> and B<N> are used to decide the bits of security, where
+B<L> is the size of the public key and B<N> is the size of the private
+key. For IFC, e.g., RSA, only B<L> is used and it's commonly considered
+to be the key size (modulus).
+
+=head1 RETURN VALUES
+
+Number of security bits.
+
+=head1 NOTES
+
+ECC (Elliptic Curve Cryptography) is not covered by the BN_security_bits()
+function. The symmetric algorithms are not covered neither.
+
+=head1 HISTORY
+
+BN_security_bits() was added in OpenSSL 1.1.0.
+
+=head1 SEE ALSO
+
+L<DH_security_bits(3)>, L<DSA_security_bits(3)>, L<RSA_security_bits(3)>
+
+=head1 COPYRIGHT
+
+Copyright 2017 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
+L<https://www.openssl.org/source/license.html>.
+
+=cut