completed test

.gitignore

@@ -0,0 +1,38 @@
+# Allowlisting gitignore template for GO projects prevents us
+# from adding various unwanted local files, such as generated
+# files, developer configurations or IDE-specific files etc.
+#
+# Recommended: Go.AllowList.gitignore
+
+# Ignore everything
+*
+/.idea/
+# But not these files...
+!/.gitignore
+!*.go
+!go.sum
+!go.mod
+!README.md
+!LICENSE
+!*.sh
+!Makefile
+!*.json
+!*.pdf
+!*.csv
+!*.py
+!*.mediawiki
+!*.did
+!*.rs
+!*.toml
+!*.png
+!*.svg
+!*.md
+!*.txt
+!*.jsonl
+!*.bin
+!*.tmpl
+!.gitmodules
+!*.yml
+!*.yaml
+# ...even if they are in subdirectories
+!*/

ecdh_test.go

@@ -0,0 +1,56 @@
+package ecdhtest
+
+import (
+	"testing"
+
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
+)
+
+func TestECDHWrongOddness(t *testing.T) {
+	var err error
+	var sk1, sk2 *btcec.PrivateKey
+	var pk1, pk2 *btcec.PublicKey
+	var pkb1, pkb2, mpkb1, mpkb2, sb1, sb2 []byte
+	var mpk1, mpk2 *btcec.PublicKey
+	for _ = range 100 {
+		if sk1, err = btcec.NewPrivateKey(); err != nil {
+			t.Error(err)
+		}
+		pk1 = sk1.PubKey()
+		pkb1 = pk1.SerializeCompressed()
+		if sk2, err = btcec.NewPrivateKey(); err != nil {
+			t.Error(err)
+		}
+		pk2 = sk2.PubKey()
+		pkb2 = pk2.SerializeCompressed()
+		if mpk1, err = secp256k1.ParsePubKey(append([]byte{0x02}, pkb1[1:]...)); err != nil {
+			return
+		}
+		if mpk2, err = secp256k1.ParsePubKey(append([]byte{0x02}, pkb2[1:]...)); err != nil {
+			return
+		}
+		mpkb1 = mpk1.SerializeCompressed()
+		mpkb2 = mpk2.SerializeCompressed()
+		sb1 = sk1.Serialize()
+		sb2 = sk2.Serialize()
+		ecdhab := btcec.GenerateSharedSecret(sk1, pk2)
+		ecdhba := btcec.GenerateSharedSecret(sk2, pk1)
+		ecdhbA := btcec.GenerateSharedSecret(sk1, mpk2)
+		ecdhaB := btcec.GenerateSharedSecret(sk2, mpk1)
+		// if !bytes.Equal(ecdhab, ecdhba) || !bytes.Equal(ecdhaB, ecdhbA) {
+		if pkb1[0] == 3 || pkb2[0] == 3 {
+			t.Logf(
+				"\nsa %0x | pa %0x = ECDHab %0x"+
+					"\nsb %0x | pb %0x = ECDHba %0x"+
+					"\nsa %0x | pA %0x = ECDHaB %0x"+
+					"\nsb %0x | pB %0x = ECDHbA %0x",
+				sb1, pkb1, ecdhab,
+				sb2, pkb2, ecdhba,
+				sb1, mpkb1, ecdhaB,
+				sb2, mpkb2, ecdhbA,
+			)
+		}
+		// }
+	}
+}

go.mod

@@ -0,0 +1,7 @@
+module github.com/mleku/ecdhtest
+
+go 1.23rc2
+
+require github.com/btcsuite/btcd/btcec/v2 v2.3.4
+
+require github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 // indirect

go.sum

@@ -0,0 +1,7 @@
+github.com/btcsuite/btcd/btcec/v2 v2.3.4 h1:3EJjcN70HCu/mwqlUsGK8GcNVyLVxFDlWurTXGPFfiQ=
+github.com/btcsuite/btcd/btcec/v2 v2.3.4/go.mod h1:zYzJ8etWJQIv1Ogk7OzpWjowwOdXY1W/17j2MW85J04=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/decred/dcrd/crypto/blake256 v1.0.0/go.mod h1:sQl2p6Y26YV+ZOcSTP6thNdn47hh8kt6rqSlvmrXFAc=
+github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 h1:YLtO71vCjJRCBcrPMtQ9nqBsqpA1m5sE92cU+pd5Mcc=
+github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1/go.mod h1:hyedUtir6IdtD/7lIxGeCxkaw7y45JueMRL4DIyJDKs=