As with RSA, which was modified recently, this change makes it possible to

override key-generation implementations by placing handlers in the methods
for DSA and DH. Also, parameter generation for DSA and DH is possible by
another new handler for each method.

crypto/dsa/dsa_key.c

@@ -64,7 +64,16 @@
 #include <openssl/dsa.h>
 #include <openssl/rand.h>
 
+static int dsa_builtin_keygen(DSA *dsa);
+
 int DSA_generate_key(DSA *dsa)
+	{
+	if(dsa->meth->dsa_keygen)
+		return dsa->meth->dsa_keygen(dsa);
+	return dsa_builtin_keygen(dsa);
+	}
+
+static int dsa_builtin_keygen(DSA *dsa)
 	{
 	int ok=0;
 	BN_CTX *ctx=NULL;