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BN_security_bits.3ossl - Man Page

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).

Return Values

Number of security bits.


ECC (Elliptic Curve Cryptography) is not covered by the BN_security_bits() function. The symmetric algorithms are not covered neither.

See Also

DH_security_bits(3), DSA_security_bits(3), RSA_security_bits(3)


The BN_security_bits() function was added in OpenSSL 1.1.0.

Referenced By

DH_size.3ossl(3), DSA_size.3ossl(3), RSA_size.3ossl(3).

2024-04-04 3.2.1 OpenSSL