From 61e29716112677a5e560f60d596040f6f7c6d1d7 Mon Sep 17 00:00:00 2001
From: MITSUNARI Shigeo <herumi@nifty.com>
Date: Tue, 30 Jun 2020 12:17:44 +0900
Subject: [PATCH] add g1cofactor

---
 include/mcl/mapto_wb19.hpp | 17 +++++++++++++----
 test/mapto_wb19_test.cpp   | 22 ++++++++++++++++------
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/include/mcl/mapto_wb19.hpp b/include/mcl/mapto_wb19.hpp
index 42fd619..a35d79c 100644
--- a/include/mcl/mapto_wb19.hpp
+++ b/include/mcl/mapto_wb19.hpp
@@ -86,6 +86,7 @@ struct MapTo_WB19 {
 	Fp g1xden[11];
 	Fp g1ynum[16];
 	Fp g1yden[16];
+	mpz_class g1cofactor;
 	int g1Z;
 	int draftVersion_;
 	void setDraftVersion(int draftVersion)
@@ -156,6 +157,8 @@ struct MapTo_WB19 {
 			g1c2.setStr(&b, c2);
 			assert(b); (void)b;
 			g1Z = 11;
+			gmp::setStr(&b, g1cofactor, "d201000000010001", 16);
+			assert(b); (void)b;
 		}
 		init_iso11();
 	}
@@ -612,11 +615,9 @@ struct MapTo_WB19 {
 		}
 		map2curve_osswu2(out, msg, msgSize, dst, strlen(dst));
 	}
-	void msgToG1(G1& out, const void *msg, size_t msgSize) const
+	void msgToG1(G1& out, const void *msg, size_t msgSize, const char *dst, size_t dstSize) const
 	{
 		assert(draftVersion_ == 7);
-		const char *dst = "BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_";
-		const size_t dstSize = strlen(dst);
 		uint8_t md[128];
 		mcl::fp::expand_message_xmd(md, sizeof(md), msg, msgSize, dst, dstSize);
 		Fp u[2];
@@ -628,8 +629,16 @@ struct MapTo_WB19 {
 		E1 P1, P2;
 		sswuG1(P1, u[0]);
 		sswuG1(P2, u[1]);
-		ec::addJacobi(P1, P1, P2); // ok
+		ec::addJacobi(P1, P1, P2);
 		iso11(out, P1);
+		G1::mulGeneric(out, out, g1cofactor);
+	}
+	void msgToG1(G1& out, const void *msg, size_t msgSize) const
+	{
+		assert(draftVersion_ == 7);
+		const char *dst = "BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_";
+		const size_t dstSize = strlen(dst);
+		msgToG1(out, msg, msgSize, dst, dstSize);
 	}
 };
 
diff --git a/test/mapto_wb19_test.cpp b/test/mapto_wb19_test.cpp
index 1938cb9..cc278e1 100644
--- a/test/mapto_wb19_test.cpp
+++ b/test/mapto_wb19_test.cpp
@@ -1105,25 +1105,35 @@ void testMsgToG1(const T& mapto)
 {
 	const struct {
 		const char *msg;
+		const char *dst;
 		const char *x;
 		const char *y;
-		const char *z;
 	} tbl[] = {
 		{
 			"asdf",
-			"14f99d14fa81bad3cc6232c0dee394235fb61287be4a262085604684a20790fbc7954ae6b2d545f05f967c9f624a116a",
-			"acfaebe113b047b38d8eb3a37bbdf77ed0d392289f642e6e7b1611305ae537fa0a574a8235042672b49f44f54d00646",
-			"1",
+			"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_",
+			"bc73d15443009a8ff2ddce864136d892274dd8365c60d0d2d44cc543387348e366a8f1e1401427e37743c29ed2c939a",
+			"101e26428a1b78c05458cb1cc37d2d87876ad3437096d2827f376702d4451667fe1fa82e82795495d33d466133ed1862",
 		},
+		// https://www.ietf.org/id/draft-irtf-cfrg-hash-to-curve-09.txt
+		// H.9.1.  BLS12381G1_XMD:SHA-256_SSWU_RO_
+		{
+			"",
+			"QUUX-V01-CS02-with-BLS12381G1_XMD:SHA-256_SSWU_RO_",
+			"052926add2207b76ca4fa57a8734416c8dc95e24501772c814278700eed6d1e4e8cf62d9c09db0fac349612b759e79a1",
+			"08ba738453bfed09cb546dbb0783dbb3a5f1f566ed67bb6be0e8c67e2e81a4cc68ee29813bb7994998f3eae0c9c6a265",
+		}
 	};
 	for (size_t i = 0; i < CYBOZU_NUM_OF_ARRAY(tbl); i++) {
 		const char *msg = tbl[i].msg;
 		const size_t msgSize = strlen(msg);
+		const char *dst = tbl[i].dst;
+		const size_t dstSize = strlen(dst);
 		G1 P, Q;
-		mapto.msgToG1(P, msg, msgSize);
+		mapto.msgToG1(P, msg, msgSize, dst, dstSize);
 		Q.x.setStr(tbl[i].x, 16);
 		Q.y.setStr(tbl[i].y, 16);
-		Q.z.setStr(tbl[i].z, 16);
+		Q.z = 1;
 		CYBOZU_TEST_EQUAL(P, Q);
 	}
 }