Updated: 2022/Sep/29

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DH_size(3)                          OpenSSL                         DH_size(3)



NAME
       DH_size, DH_bits, DH_security_bits - get Diffie-Hellman prime size and
       security bits

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/dh.h>

       The following functions have been deprecated since OpenSSL 3.0, and 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.

COPYRIGHT
       Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.



3.0.12                            2023-05-07                        DH_size(3)