added generate shared keypair

README.md

@@ -68,6 +68,7 @@ View the generated [documentation](https://pkg.go.dev/github.com/bitcoinschema/g
   - [Create PrivateKey](private_key.go)
   - [PrivateKey (string) to Address (string)](address.go)
   - [PrivateKey from string](private_key.go)
+  - [Generate Shared Keypair](private_key.go)
   - [Get Private and Public keys](private_key.go)
   - [WIF to PrivateKey](private_key.go)
   - [PrivateKey to WIF](private_key.go)

private_key.go

@@ -11,6 +11,13 @@ import (
 	"github.com/bitcoinsv/bsvutil"
 )
 
+// GenerateSharedKeyPair creates shared keys that can be used to encrypt/decrypt data that can be decrypted by yourself (privkey) and also the owner of the given public key
+func GenerateSharedKeyPair(privKey *bsvec.PrivateKey, pubKey *bsvec.PublicKey) (sharedPrivKey *bsvec.PrivateKey, sharedPubKey *bsvec.PublicKey, err error) {
+	sharedSecret := bsvec.GenerateSharedSecret(privKey, pubKey)
+	sharedPrivKey, sharedPubKey = bsvec.PrivKeyFromBytes(bsvec.S256(), sharedSecret)
+	return
+}
+
 // PrivateKeyFromString turns a private key (hex encoded string) into an bsvec.PrivateKey
 func PrivateKeyFromString(privateKey string) (*bsvec.PrivateKey, error) {
 	if len(privateKey) == 0 {

private_key_test.go

@@ -4,8 +4,51 @@ import (
 	"encoding/hex"
 	"fmt"
 	"testing"
+
+	"github.com/bitcoinsv/bsvd/bsvec"
 )
 
+// TestGenerateSharedKeyPair will test creating a shared key that can be used to encrypt data that can be decrypted by yourself (privkey) and also the owner of the given public key
+func TestGenerateSharedKeyPair(t *testing.T) {
+
+	// The data that will be encrypted / shared
+	testString := "testing 1, 2, 3..."
+
+	// User 1
+	privKey1, _ := CreatePrivateKey()
+
+	// User 2
+	privKey2, _ := CreatePrivateKey()
+
+	_, user1SharedPubKey, err := GenerateSharedKeyPair(privKey1, privKey2.PubKey())
+	if err != nil {
+		t.Errorf("Failed to generate a shared key pair %s", err)
+	}
+
+	// encrypt something with the shared public key
+	eciesTest, err := bsvec.Encrypt(user1SharedPubKey, []byte(testString))
+	if err != nil {
+		t.Errorf("Failed to encrypt test data %s", err)
+	}
+
+	// user 2 decrypts it
+	user2SharedPrivKey, _, err := GenerateSharedKeyPair(privKey2, privKey1.PubKey())
+	if err != nil {
+		t.Errorf("Failed to generate a shared key pair %s", err)
+	}
+
+	decryptedTestData, err := bsvec.Decrypt(user2SharedPrivKey, eciesTest)
+	if err != nil {
+		t.Errorf("Failed to decrypt test data %s", err)
+	}
+
+	if string(decryptedTestData) != testString {
+		t.Errorf("Decrypted string doesnt match %s", decryptedTestData)
+	}
+
+	return
+}
+
 // TestCreatePrivateKey will test the method CreatePrivateKey()
 func TestCreatePrivateKey(t *testing.T) {
 	rawKey, err := CreatePrivateKey()