From be54124ccf649ace15ef0f90dbf04f01fab8ac3c Mon Sep 17 00:00:00 2001
From: MITSUNARI Shigeo <herumi@nifty.com>
Date: Thu, 13 Sep 2018 05:23:28 +0900
Subject: add bls*Sub functions

---
 include/bls/bls.h      |  5 +++++
 src/bls_c.cpp          | 14 ++++++++++++++
 test/bls_c384_test.cpp | 39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+)

diff --git a/include/bls/bls.h b/include/bls/bls.h
index 7188097..21cd5b0 100644
--- a/include/bls/bls.h
+++ b/include/bls/bls.h
@@ -122,6 +122,11 @@ BLS_DLL_API int blsPublicKeyIsValidOrder(const blsPublicKey *pub);
 
 #ifndef BLS_MINIMUM_API
 
+// sub
+BLS_DLL_API void blsSecretKeySub(blsSecretKey *sec, const blsSecretKey *rhs);
+BLS_DLL_API void blsPublicKeySub(blsPublicKey *pub, const blsPublicKey *rhs);
+BLS_DLL_API void blsSignatureSub(blsSignature *sig, const blsSignature *rhs);
+
 // not thread safe version (old blsInit)
 BLS_DLL_API int blsInitNotThreadSafe(int curve, int maxUnitSize);
 
diff --git a/src/bls_c.cpp b/src/bls_c.cpp
index 06a5b0a..75e5a44 100644
--- a/src/bls_c.cpp
+++ b/src/bls_c.cpp
@@ -267,6 +267,20 @@ int blsPublicKeyIsValidOrder(const blsPublicKey *pub)
 }
 
 #ifndef BLS_MINIMUM_API
+void blsSecretKeySub(blsSecretKey *sec, const blsSecretKey *rhs)
+{
+	mclBnFr_sub(&sec->v, &sec->v, &rhs->v);
+}
+
+void blsPublicKeySub(blsPublicKey *pub, const blsPublicKey *rhs)
+{
+	mclBnG2_sub(&pub->v, &pub->v, &rhs->v);
+}
+
+void blsSignatureSub(blsSignature *sig, const blsSignature *rhs)
+{
+	mclBnG1_sub(&sig->v, &sig->v, &rhs->v);
+}
 mclSize blsGetOpUnitSize() // FpUint64Size
 {
 	return Fp::getUnitSize() * sizeof(mcl::fp::Unit) / sizeof(uint64_t);
diff --git a/test/bls_c384_test.cpp b/test/bls_c384_test.cpp
index 984c9c3..ede3596 100644
--- a/test/bls_c384_test.cpp
+++ b/test/bls_c384_test.cpp
@@ -250,6 +250,44 @@ void blsVerifyOrderTest()
 	blsSignatureVerifyOrder(1);
 }
 
+void blsAddSubTest()
+{
+	blsSecretKey sec[3];
+	blsPublicKey pub[3];
+	blsSignature sig[3];
+	const char *msg = "this is a pen";
+	const size_t msgSize = strlen(msg);
+
+	const char *secHexStr[8] = { "12", "34" };
+	for (int i = 0; i < 2; i++) {
+		blsSecretKeySetHexStr(&sec[i], secHexStr[i], strlen(secHexStr[i]));
+		blsGetPublicKey(&pub[i], &sec[i]);
+		blsSign(&sig[i], &sec[i], msg, msgSize);
+	}
+	sec[2] = sec[0];
+	blsSecretKeyAdd(&sec[2], &sec[1]);
+	char buf[1024];
+	size_t n = blsSecretKeyGetHexStr(buf, sizeof(buf), &sec[2]);
+	CYBOZU_TEST_EQUAL(n, 2);
+	CYBOZU_TEST_EQUAL(buf, "46"); // "12" + "34"
+
+	pub[2] = pub[0];
+	blsPublicKeyAdd(&pub[2], &pub[1]);
+	sig[2] = sig[0];
+	blsSignatureAdd(&sig[2], &sig[1]); // sig[2] = sig[0] + sig[1]
+	blsSignature sig2;
+	blsSign(&sig2, &sec[2], msg, msgSize); // sig2 = signature by sec[2]
+	CYBOZU_TEST_ASSERT(blsSignatureIsEqual(&sig2, &sig[2]));
+	CYBOZU_TEST_ASSERT(blsVerify(&sig[2], &pub[2], msg, msgSize)); // verify by pub[2]
+
+	blsSecretKeySub(&sec[2], &sec[1]);
+	CYBOZU_TEST_ASSERT(blsSecretKeyIsEqual(&sec[2], &sec[0]));
+	blsPublicKeySub(&pub[2], &pub[1]);
+	CYBOZU_TEST_ASSERT(blsPublicKeyIsEqual(&pub[2], &pub[0]));
+	blsSignatureSub(&sig[2], &sig[1]);
+	CYBOZU_TEST_ASSERT(blsSignatureIsEqual(&sig[2], &sig[0]));
+}
+
 CYBOZU_TEST_AUTO(all)
 {
 	const int tbl[] = {
@@ -277,5 +315,6 @@ CYBOZU_TEST_AUTO(all)
 		blsOrderTest(curveOrderTbl[i], fieldOrderTbl[i]);
 		blsSerializeTest();
 		if (tbl[i] == MCL_BLS12_381) blsVerifyOrderTest();
+		blsAddSubTest();
 	}
 }
-- 
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