DSA: Add export of keys and domain parameters from provider

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10169)

providers/implementations/keymgmt/dsa_kmgmt.c

@@ -15,7 +15,9 @@
 #include "prov/implementations.h"
 
 static OSSL_OP_keymgmt_importdomparams_fn dsa_importdomparams;
+static OSSL_OP_keymgmt_exportdomparams_fn dsa_exportdomparams;
 static OSSL_OP_keymgmt_importkey_fn dsa_importkey;
+static OSSL_OP_keymgmt_exportkey_fn dsa_exportkey;
 
 static int params_to_domparams(DSA *dsa, const OSSL_PARAM params[])
 {
@@ -46,6 +48,28 @@ static int params_to_domparams(DSA *dsa, const OSSL_PARAM params[])
     return 0;
 }
 
+static int domparams_to_params(DSA *dsa, OSSL_PARAM params[])
+{
+    OSSL_PARAM *p;
+    const BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL;
+
+    if (dsa == NULL)
+        return 0;
+
+    DSA_get0_pqg(dsa, &dsa_p, &dsa_q, &dsa_g);
+    if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_FFC_P)) != NULL
+        && !OSSL_PARAM_set_BN(p, dsa_p))
+        return 0;
+    if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_FFC_Q)) != NULL
+        && !OSSL_PARAM_set_BN(p, dsa_q))
+        return 0;
+    if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_FFC_G)) != NULL
+        && !OSSL_PARAM_set_BN(p, dsa_g))
+        return 0;
+
+    return 1;
+}
+
 static int params_to_key(DSA *dsa, const OSSL_PARAM params[])
 {
     const OSSL_PARAM *param_priv_key, *param_pub_key;
@@ -86,6 +110,27 @@ static int params_to_key(DSA *dsa, const OSSL_PARAM params[])
     return 0;
 }
 
+static int key_to_params(DSA *dsa, OSSL_PARAM params[])
+{
+    OSSL_PARAM *p;
+    const BIGNUM *priv_key = NULL, *pub_key = NULL;
+
+    if (dsa == NULL)
+        return 0;
+    if (!domparams_to_params(dsa, params))
+        return 0;
+
+    DSA_get0_key(dsa, &pub_key, &priv_key);
+    if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_DSA_PRIV_KEY)) != NULL
+        && !OSSL_PARAM_set_BN(p, priv_key))
+        return 0;
+    if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_DSA_PUB_KEY)) != NULL
+        && !OSSL_PARAM_set_BN(p, pub_key))
+        return 0;
+
+    return 1;
+}
+
 static void *dsa_importdomparams(void *provctx, const OSSL_PARAM params[])
 {
     DSA *dsa;
@@ -98,6 +143,13 @@ static void *dsa_importdomparams(void *provctx, const OSSL_PARAM params[])
     return dsa;
 }
 
+static int dsa_exportdomparams(void *domparams, OSSL_PARAM params[])
+{
+    DSA *dsa = domparams;
+
+    return dsa != NULL && !domparams_to_params(dsa, params);
+}
+
 static void *dsa_importkey(void *provctx, const OSSL_PARAM params[])
 {
     DSA *dsa;
@@ -110,14 +162,23 @@ static void *dsa_importkey(void *provctx, const OSSL_PARAM params[])
     return dsa;
 }
 
+static int dsa_exportkey(void *key, OSSL_PARAM params[])
+{
+    DSA *dsa = key;
+
+    return dsa != NULL && !key_to_params(dsa, params);
+}
+
 const OSSL_DISPATCH dsa_keymgmt_functions[] = {
     /*
      * TODO(3.0) When implementing OSSL_FUNC_KEYMGMT_GENKEY, remember to also
      * implement OSSL_FUNC_KEYMGMT_EXPORTKEY.
      */
     { OSSL_FUNC_KEYMGMT_IMPORTDOMPARAMS, (void (*)(void))dsa_importdomparams },
+    { OSSL_FUNC_KEYMGMT_EXPORTDOMPARAMS, (void (*)(void))dsa_exportdomparams },
     { OSSL_FUNC_KEYMGMT_FREEDOMPARAMS, (void (*)(void))DSA_free },
     { OSSL_FUNC_KEYMGMT_IMPORTKEY, (void (*)(void))dsa_importkey },
+    { OSSL_FUNC_KEYMGMT_EXPORTKEY, (void (*)(void))dsa_exportkey },
     { OSSL_FUNC_KEYMGMT_FREEKEY, (void (*)(void))DSA_free },
     { 0, NULL }
 };