DSA_dup_DH.3ssl man page

 #include <openssl/dsa.h>

 DH * DSA_dup_DH(const DSA *r);

DSA_dup_DH() duplicates DSA parameters/keys as DH parameters/keys. q is lost during that conversion, but the resulting DH parameters contain its length.

DSA_dup_DH() returns the new DH structure, and NULL on error. The error codes can be obtained by ERR_get_error(3).

Be careful to avoid small subgroup attacks when using this.

dh(3), dsa(3), ERR_get_error(3)

DSA_dup_DH() was added in OpenSSL 0.9.4.