crypto.ecda: improvement the performance of PrivateKey.new by avoiding match+assignments (#23899)

Author: blackshirt

vlib/crypto/ecdsa/ecdsa.v

@@ -166,21 +166,6 @@ mut:
 // PrivateKey.new creates a new key pair. By default, it would create a prime256v1 based key.
 // Dont forget to call `.free()` after finish with your key.
 pub fn PrivateKey.new(opt CurveOptions) !PrivateKey {
-	// Default to prime256v1 based key
-	mut group_nid := nid_prime256v1
-	match opt.nid {
-		.prime256v1 {}
-		.secp384r1 {
-			group_nid = nid_secp384r1
-		}
-		.secp521r1 {
-			group_nid = nid_secp521r1
-		}
-		.secp256k1 {
-			group_nid = nid_secp256k1
-		}
-	}
-	// New high level keypair generator
 	evpkey := C.EVP_PKEY_new()
 	pctx := C.EVP_PKEY_CTX_new_id(nid_evp_pkey_ec, 0)
 	if pctx == 0 {
@@ -195,7 +180,7 @@ pub fn PrivateKey.new(opt CurveOptions) !PrivateKey {
 		return error('EVP_PKEY_keygen_init failed')
 	}
 	// set the group (curve)
-	cn := C.EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, group_nid)
+	cn := C.EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, int(opt.nid))
 	if cn <= 0 {
 		C.EVP_PKEY_free(evpkey)
 		C.EVP_PKEY_CTX_free(pctx)