DH_size.3ossl - Man Page

get Diffie-Hellman prime size and security bits

Synopsis

 #include <openssl/dh.h>

Deprecated since OpenSSL 3.0, can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

 int DH_bits(const DH *dh);

 int DH_size(const DH *dh);

 int DH_security_bits(const DH *dh);

Description

The functions described on this page are deprecated. Applications should instead use EVP_PKEY_get_bits(3), EVP_PKEY_get_security_bits(3) and EVP_PKEY_get_size(3).

DH_bits() returns the number of significant bits.

dh and dh->p must not be NULL.

DH_size() returns the Diffie-Hellman prime size in bytes. It can be used to determine how much memory must be allocated for the shared secret computed by DH_compute_key(3).

DH_security_bits() returns the number of security bits of the given dh key. See BN_security_bits(3).

Return Values

DH_bits() returns the number of bits in the key, or -1 if dh doesn't hold any key parameters.

DH_size() returns the prime size of Diffie-Hellman in bytes, or -1 if dh doesn't hold any key parameters.

DH_security_bits() returns the number of security bits, or -1 if dh doesn't hold any key parameters.

See Also

EVP_PKEY_get_bits(3), DH_new(3), DH_generate_key(3), BN_num_bits(3)

History

All functions were deprecated in OpenSSL 3.0.

Referenced By

BN_num_bytes.3ossl(3), DH_generate_key.3ossl(3), DH_get0_pqg.3ossl(3), DH_meth_new.3ossl(3).

The man pages DH_bits.3ossl(3) and DH_security_bits.3ossl(3) are aliases of DH_size.3ossl(3).

2021-09-09 3.0.0 OpenSSL