add blsDHKeyExchange

4 files changed, 30 insertions, 0 deletions

diff --git a/go/bls/bls.go b/go/bls/bls.go
index 2812697..61a96f5 100644
--- a/go/bls/bls.go
+++ b/go/bls/bls.go
@@ -288,3 +288,9 @@ func (sign *Sign) Verify(pub *PublicKey, m string) bool {
 func (sign *Sign) VerifyPop(pub *PublicKey) bool {
 	return C.blsVerifyPop(sign.getPointer(), pub.getPointer()) == 1
 }
+
+// DHKeyExchange --
+func DHKeyExchange(sec *SecretKey, pub *PublicKey) (out PublicKey) {
+	C.blsDHKeyExchange(out.getPointer(), sec.getPointer(), pub.getPointer())
+	return out
+}
diff --git a/go/bls/bls_test.go b/go/bls/bls_test.go
index 31f7f8a..998dd1f 100644
--- a/go/bls/bls_test.go
+++ b/go/bls/bls_test.go
@@ -305,6 +305,19 @@ func testOrder(t *testing.T, c int) {
 	}
 }
 
+func testDHKeyExchange(t *testing.T) {
+	var sec1, sec2 SecretKey
+	sec1.SetByCSPRNG()
+	sec2.SetByCSPRNG()
+	pub1 := sec1.GetPublicKey()
+	pub2 := sec2.GetPublicKey()
+	out1 := DHKeyExchange(&sec1, pub2)
+	out2 := DHKeyExchange(&sec2, pub1)
+	if !out1.IsEqual(&out2) {
+		t.Errorf("DH key is not equal")
+	}
+}
+
 func test(t *testing.T, c int) {
 	err := Init(c)
 	if err != nil {
@@ -321,6 +334,7 @@ func test(t *testing.T, c int) {
 	testData(t)
 	testStringConversion(t)
 	testOrder(t, c)
+	testDHKeyExchange(t)
 }
 
 func TestMain(t *testing.T) {
diff --git a/include/bls/bls.h b/include/bls/bls.h
index 37c337d..a56120c 100644
--- a/include/bls/bls.h
+++ b/include/bls/bls.h
@@ -170,6 +170,11 @@ BLS_DLL_API size_t blsPublicKeyGetHexStr(char *buf, size_t maxBufSize, const bls
 BLS_DLL_API int blsSignatureSetHexStr(blsSignature *sig, const char *buf, size_t bufSize);
 BLS_DLL_API size_t blsSignatureGetHexStr(char *buf, size_t maxBufSize, const blsSignature *sig);
 
+/*
+	Diffie Hellman key exchange
+	out = sec * pub
+*/
+BLS_DLL_API void blsDHKeyExchange(blsPublicKey *out, const blsSecretKey *sec, const blsPublicKey *pub);
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/bls_c.cpp b/src/bls_c.cpp
index 27cf226..64ff5bc 100644
--- a/src/bls_c.cpp
+++ b/src/bls_c.cpp
@@ -391,3 +391,8 @@ size_t blsSignatureGetHexStr(char *buf, size_t maxBufSize, const blsSignature *s
 {
 	return mclBnG1_getStr(buf, maxBufSize, &sig->v, 16);
 }
+void blsDHKeyExchange(blsPublicKey *out, const blsSecretKey *sec, const blsPublicKey *pub)
+{
+	mclBnG2_mul(&out->v, &pub->v, &sec->v);
+}
+