Allow to use raw VKO in EVP_PKEY_derive

Suitable for tests. Use EVP_PKEY_CTRL_SET_VKO ctrl with appropriate
digest nid to enable VKO mode.

3 files changed, 40 insertions, 3 deletions

diff --git a/gost_ec_keyx.c b/gost_ec_keyx.c
index 89884ce..6762d4c 100644
--- a/gost_ec_keyx.c
+++ b/gost_ec_keyx.c
@@ -120,6 +120,7 @@ int VKO_compute_key(unsigned char *shared_key,
 }
 
 /*
+ * KEG Algorithm described in R 1323565.1.020-2018 6.4.5.1.
  * keyout expected to be 64 bytes
  * */
 static int gost_keg(const unsigned char *ukm_source, int pkey_nid,
@@ -175,6 +176,10 @@ static int gost_keg(const unsigned char *ukm_source, int pkey_nid,
  * EVP_PKEY_METHOD callback derive.
  * Implements VKO R 34.10-2001/2012 algorithms
  */
+/*
+ * Backend for EVP_PKEY_derive()
+ * It have KEG mode (default) and VKO mode (enable by EVP_PKEY_CTRL_SET_VKO).
+ */
 int pkey_gost_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
 {
     /*
@@ -191,11 +196,26 @@ int pkey_gost_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
         GOSTerr(GOST_F_PKEY_GOST_EC_DERIVE, GOST_R_UKM_NOT_SET);
         return 0;
     }
+
+    /* VKO */
+    if (data->vko_dgst_nid) {
+        if (!key) {
+            *keylen = data->vko_dgst_nid == NID_id_GostR3411_2012_256? 32 : 64;
+            return 1;
+        }
+        *keylen = VKO_compute_key(key,
+                                  EC_KEY_get0_public_key(EVP_PKEY_get0(peer_key)),
+                                  (EC_KEY *)EVP_PKEY_get0(my_key),
+                                  data->shared_ukm, data->shared_ukm_size,
+                                  data->vko_dgst_nid);
+        return (*keylen) ? 1 : 0;
+    }
+
     /*
      * shared_ukm_size = 8 stands for pre-2018 cipher suites
      * It means 32 bytes of key length, 8 byte UKM, 32-bytes hash
      *
-     * shared_ukm_size = 32 stands for pre-2018 cipher suites
+     * shared_ukm_size = 32 stands for post-2018 cipher suites
      * It means 64 bytes of shared_key, 16 bytes of UKM and either
      * 64 bytes of hash or 64 bytes of TLSTREE output
      * */
@@ -207,7 +227,6 @@ int pkey_gost_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
                 *keylen = 32;
                 return 1;
             }
-
             EVP_PKEY_get_default_digest_nid(my_key, &dgst_nid);
             if (dgst_nid == NID_id_GostR3411_2012_512)
                 dgst_nid = NID_id_GostR3411_2012_256;
@@ -702,3 +721,4 @@ int pkey_gost_decrypt(EVP_PKEY_CTX *pctx, unsigned char *key,
       return -1;
     }
 }
+/* vim: set expandtab cinoptions=\:0,l1,t0,g0,(0 sw=4 : */
diff --git a/gost_lcl.h b/gost_lcl.h
index c60d8d2..50446a3 100644
--- a/gost_lcl.h
+++ b/gost_lcl.h
@@ -64,6 +64,7 @@ int register_pmeth_gost(int id, EVP_PKEY_METHOD **pmeth, int flags);
 # define maclen_ctrl_string "size"
 # define EVP_PKEY_CTRL_GOST_MAC_HEXKEY (EVP_PKEY_ALG_CTRL+3)
 # define EVP_PKEY_CTRL_MAC_LEN (EVP_PKEY_ALG_CTRL+5)
+# define EVP_PKEY_CTRL_SET_VKO (EVP_PKEY_ALG_CTRL+11)
 /* Pmeth internal representation */
 struct gost_pmeth_data {
     int sign_param_nid;         /* Should be set whenever parameters are
@@ -73,6 +74,7 @@ struct gost_pmeth_data {
     size_t shared_ukm_size;
     int peer_key_used;
     int cipher_nid;             /* KExp15/KImp15 algs */
+    int vko_dgst_nid;
 };
 
 struct gost_mac_pmeth_data {
diff --git a/gost_pmeth.c b/gost_pmeth.c
index af92fbf..bceb50e 100644
--- a/gost_pmeth.c
+++ b/gost_pmeth.c
@@ -148,10 +148,25 @@ static int pkey_gost_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
         pctx->sign_param_nid = (int)p1;
         return 1;
     case EVP_PKEY_CTRL_SET_IV:
-        OPENSSL_assert(p2 != NULL);
+	if (p1 > sizeof(pctx->shared_ukm) || !p2) {
+	    GOSTerr(GOST_F_PKEY_GOST_CTRL, GOST_R_UKM_NOT_SET);
+	    return 0;
+	}
         memcpy(pctx->shared_ukm, p2, (int)p1);
         pctx->shared_ukm_size = p1;
         return 1;
+    case EVP_PKEY_CTRL_SET_VKO:
+	switch (p1) {
+	    case 0: /* switch to KEG */
+	    case NID_id_GostR3411_2012_256:
+	    case NID_id_GostR3411_2012_512:
+		break;
+	    default:
+		GOSTerr(GOST_F_PKEY_GOST_CTRL, GOST_R_INVALID_DIGEST_TYPE);
+		return 0;
+	}
+        pctx->vko_dgst_nid = p1;
+        return 1;
   case EVP_PKEY_CTRL_CIPHER:
         switch (p1) {
           case NID_magma_ctr_acpkm: