1 files changed, 33 insertions, 1 deletions

diff --git a/src/lib/libcrypto/ecdsa/ecs_ossl.c b/src/lib/libcrypto/ecdsa/ecs_ossl.c
index 547d3b59e1..251a938e2d 100644
--- a/src/lib/libcrypto/ecdsa/ecs_ossl.c
+++ b/src/lib/libcrypto/ecdsa/ecs_ossl.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ecs_ossl.c,v 1.36 2023/06/25 19:04:35 tb Exp $ */
+/* $OpenBSD: ecs_ossl.c,v 1.37 2023/06/25 19:33:39 tb Exp $ */
 /*
  * Written by Nils Larsch for the OpenSSL project
  */
@@ -580,3 +580,35 @@ ECDSA_verify(int type, const unsigned char *dgst, int dgst_len,
         ECDSAerror(EVP_R_METHOD_NOT_SUPPORTED);
         return 0;
 }
+
+int
+ECDSA_size(const EC_KEY *r)
+{
+        BIGNUM *order = NULL;
+        const EC_GROUP *group;
+        ECDSA_SIG signature;
+        int ret = 0;
+
+        if (r == NULL)
+                goto err;
+
+        if ((group = EC_KEY_get0_group(r)) == NULL)
+                goto err;
+
+        if ((order = BN_new()) == NULL)
+                goto err;
+
+        if (!EC_GROUP_get_order(group, order, NULL))
+                goto err;
+
+        signature.r = order;
+        signature.s = order;
+
+        if ((ret = i2d_ECDSA_SIG(&signature, NULL)) < 0)
+                ret = 0;
+
+ err:
+        BN_free(order);
+
+        return ret;
+}