diff --git a/include/mcl/she.h b/include/mcl/she.h
index 8a17150..c15fb0b 100644
--- a/include/mcl/she.h
+++ b/include/mcl/she.h
@@ -78,6 +78,14 @@ typedef struct {
 typedef struct {
 	mclBnFr d[2];
 } sheZkpDec;
+
+typedef struct {
+	mclBnGT d[4];
+} sheAuxiliaryForZkpDecGT;
+
+typedef struct {
+	mclBnFr d[4];
+} sheZkpDecGT;
 /*
 	initialize this library
 	call this once before using the other functions
@@ -101,6 +109,7 @@ MCLSHE_DLL_API mclSize sheZkpBinSerialize(void *buf, mclSize maxBufSize, const s
 MCLSHE_DLL_API mclSize sheZkpEqSerialize(void *buf, mclSize maxBufSize, const sheZkpEq *zkp);
 MCLSHE_DLL_API mclSize sheZkpBinEqSerialize(void *buf, mclSize maxBufSize, const sheZkpBinEq *zkp);
 MCLSHE_DLL_API mclSize sheZkpDecSerialize(void *buf, mclSize maxBufSize, const sheZkpDec *zkp);
+MCLSHE_DLL_API mclSize sheZkpDecGTSerialize(void *buf, mclSize maxBufSize, const sheZkpDecGT *zkp);
 
 // return read byte size if sucess else 0
 MCLSHE_DLL_API mclSize sheSecretKeyDeserialize(sheSecretKey* sec, const void *buf, mclSize bufSize);
@@ -112,6 +121,7 @@ MCLSHE_DLL_API mclSize sheZkpBinDeserialize(sheZkpBin* zkp, const void *buf, mcl
 MCLSHE_DLL_API mclSize sheZkpEqDeserialize(sheZkpEq* zkp, const void *buf, mclSize bufSize);
 MCLSHE_DLL_API mclSize sheZkpBinEqDeserialize(sheZkpBinEq* zkp, const void *buf, mclSize bufSize);
 MCLSHE_DLL_API mclSize sheZkpDecDeserialize(sheZkpDec* zkp, const void *buf, mclSize bufSize);
+MCLSHE_DLL_API mclSize sheZkpDecGTDeserialize(sheZkpDecGT* zkp, const void *buf, mclSize bufSize);
 
 /*
 	set secretKey if system has /dev/urandom or CryptGenRandom
@@ -121,6 +131,8 @@ MCLSHE_DLL_API int sheSecretKeySetByCSPRNG(sheSecretKey *sec);
 
 MCLSHE_DLL_API void sheGetPublicKey(shePublicKey *pub, const sheSecretKey *sec);
 
+MCLSHE_DLL_API void sheGetAuxiliaryForZkpDecGT(sheAuxiliaryForZkpDecGT *aux, const shePublicKey *pub);
+
 /*
 	make table to decode DLP
 	return 0 if success
@@ -203,6 +215,7 @@ MCLSHE_DLL_API int shePrecomputedPublicKeyEncWithZkpEq(sheCipherTextG1 *c1, sheC
 	return 0 if success
 */
 MCLSHE_DLL_API int sheDecWithZkpDecG1(mclInt *m, sheZkpDec *zkp, const sheSecretKey *sec, const sheCipherTextG1 *c, const shePublicKey *pub);
+MCLSHE_DLL_API int sheDecWithZkpDecGT(mclInt *m, sheZkpDecGT *zkp, const sheSecretKey *sec, const sheCipherTextGT *c, const sheAuxiliaryForZkpDecGT *aux);
 
 /*
 	decode c and set m
@@ -224,6 +237,7 @@ MCLSHE_DLL_API int shePrecomputedPublicKeyVerifyZkpBinG2(const shePrecomputedPub
 MCLSHE_DLL_API int shePrecomputedPublicKeyVerifyZkpEq(const shePrecomputedPublicKey *ppub, const sheCipherTextG1 *c1, const sheCipherTextG2 *c2, const sheZkpEq *zkp);
 MCLSHE_DLL_API int shePrecomputedPublicKeyVerifyZkpBinEq(const shePrecomputedPublicKey *ppub, const sheCipherTextG1 *c1, const sheCipherTextG2 *c2, const sheZkpBinEq *zkp);
 MCLSHE_DLL_API int sheVerifyZkpDecG1(const shePublicKey *pub, const sheCipherTextG1 *c1, mclInt m, const sheZkpDec *zkp);
+MCLSHE_DLL_API int sheVerifyZkpDecGT(const sheAuxiliaryForZkpDecGT *aux, const sheCipherTextGT *ct, mclInt m, const sheZkpDecGT *zkp);
 /*
 	decode c via GT and set m
 	return 0 if success
diff --git a/src/she_c_impl.hpp b/src/she_c_impl.hpp
index 6fcb2d3..2878163 100644
--- a/src/she_c_impl.hpp
+++ b/src/she_c_impl.hpp
@@ -44,6 +44,12 @@ static const ZkpBinEq *cast(const sheZkpBinEq *p) { return reinterpret_cast<cons
 static ZkpDec *cast(sheZkpDec *p) { return reinterpret_cast<ZkpDec*>(p); }
 static const ZkpDec *cast(const sheZkpDec *p) { return reinterpret_cast<const ZkpDec*>(p); }
 
+static AuxiliaryForZkpDecGT *cast(sheAuxiliaryForZkpDecGT *p) { return reinterpret_cast<AuxiliaryForZkpDecGT*>(p); }
+static const AuxiliaryForZkpDecGT *cast(const sheAuxiliaryForZkpDecGT *p) { return reinterpret_cast<const AuxiliaryForZkpDecGT*>(p); }
+
+static ZkpDecGT *cast(sheZkpDecGT *p) { return reinterpret_cast<ZkpDecGT*>(p); }
+static const ZkpDecGT *cast(const sheZkpDecGT *p) { return reinterpret_cast<const ZkpDecGT*>(p); }
+
 int sheInit(int curve, int compiledTimeVar)
 	try
 {
@@ -124,6 +130,11 @@ mclSize sheZkpDecSerialize(void *buf, mclSize maxBufSize, const sheZkpDec *zkp)
 	return (mclSize)cast(zkp)->serialize(buf, maxBufSize);
 }
 
+mclSize sheZkpGTDecSerialize(void *buf, mclSize maxBufSize, const sheZkpDecGT *zkp)
+{
+	return (mclSize)cast(zkp)->serialize(buf, maxBufSize);
+}
+
 mclSize sheSecretKeyDeserialize(sheSecretKey* sec, const void *buf, mclSize bufSize)
 {
 	return (mclSize)cast(sec)->deserialize(buf, bufSize);
@@ -169,6 +180,11 @@ mclSize sheZkpDecDeserialize(sheZkpDec* zkp, const void *buf, mclSize bufSize)
 	return (mclSize)cast(zkp)->deserialize(buf, bufSize);
 }
 
+mclSize sheZkpDecGTDeserialize(sheZkpDecGT* zkp, const void *buf, mclSize bufSize)
+{
+	return (mclSize)cast(zkp)->deserialize(buf, bufSize);
+}
+
 int sheSecretKeySetByCSPRNG(sheSecretKey *sec)
 {
 	cast(sec)->setByCSPRNG();
@@ -180,6 +196,11 @@ void sheGetPublicKey(shePublicKey *pub, const sheSecretKey *sec)
 	cast(sec)->getPublicKey(*cast(pub));
 }
 
+void sheGetAuxiliaryForZkpDecGT(sheAuxiliaryForZkpDecGT *aux, const shePublicKey *pub)
+{
+	cast(pub)->getAuxiliaryForZkpDecGT(*cast(aux));
+}
+
 static int wrapSetRangeForDLP(void f(size_t), mclSize hashSize)
 	try
 {
@@ -788,8 +809,20 @@ int sheDecWithZkpDecG1(mclInt *m, sheZkpDec *zkp, const sheSecretKey *sec, const
 	return b ? 0 : -1;
 }
 
+int sheDecWithZkpDecGT(mclInt *m, sheZkpDecGT *zkp, const sheSecretKey *sec, const sheCipherTextGT *c, const sheAuxiliaryForZkpDecGT *aux)
+{
+	bool b;
+	*m = cast(sec)->decWithZkpDec(&b, *cast(zkp), *cast(c), *cast(aux));
+	return b ? 0 : -1;
+}
+
 int sheVerifyZkpDecG1(const shePublicKey *pub, const sheCipherTextG1 *c1, mclInt m, const sheZkpDec *zkp)
 {
 	return cast(pub)->verify(*cast(c1), m, *cast(zkp));
 }
 
+int sheVerifyZkpDecGT(const sheAuxiliaryForZkpDecGT *aux, const sheCipherTextGT *ct, mclInt m, const sheZkpDecGT *zkp)
+{
+	return cast(aux)->verify(*cast(ct), m, *cast(zkp));
+}
+
diff --git a/test/she_c_test.hpp b/test/she_c_test.hpp
index b00b6a2..9f48942 100644
--- a/test/she_c_test.hpp
+++ b/test/she_c_test.hpp
@@ -442,7 +442,7 @@ void ZkpEqTest(const sheSecretKey *sec, const PK *pub, encWithZkpFunc encWithZkp
 	}
 }
 
-CYBOZU_TEST_AUTO(ZkpEq)
+CYBOZU_TEST_AUTO(ZkpDecG1)
 {
 	sheSecretKey sec;
 	sheSecretKeySetByCSPRNG(&sec);
@@ -464,7 +464,31 @@ CYBOZU_TEST_AUTO(ZkpEq)
 	CYBOZU_TEST_EQUAL(sheVerifyZkpDecG1(&pub, &c1, m, &zkp), 0);
 }
 
-CYBOZU_TEST_AUTO(ZkpDec)
+CYBOZU_TEST_AUTO(ZkpDecGT)
+{
+	sheSecretKey sec;
+	sheSecretKeySetByCSPRNG(&sec);
+	shePublicKey pub;
+	sheGetPublicKey(&pub, &sec);
+	sheAuxiliaryForZkpDecGT aux;
+	sheGetAuxiliaryForZkpDecGT(&aux, &pub);
+	int m = 123;
+	sheCipherTextGT c1;
+	sheEncGT(&c1, &pub, m);
+	sheZkpDecGT zkp;
+	int64_t dec;
+	CYBOZU_TEST_EQUAL(sheDecWithZkpDecGT(&dec, &zkp, &sec, &c1, &aux), 0);
+	CYBOZU_TEST_EQUAL(m, dec);
+	CYBOZU_TEST_EQUAL(sheVerifyZkpDecGT(&aux, &c1, m, &zkp), 1);
+	CYBOZU_TEST_EQUAL(sheVerifyZkpDecGT(&aux, &c1, m + 1, &zkp), 0);
+	sheCipherTextGT c2;
+	sheEncGT(&c2, &pub, m);
+	CYBOZU_TEST_EQUAL(sheVerifyZkpDecGT(&aux, &c2, m, &zkp), 0);
+	zkp.d[0].d[0]++;
+	CYBOZU_TEST_EQUAL(sheVerifyZkpDecGT(&aux, &c1, m, &zkp), 0);
+}
+
+CYBOZU_TEST_AUTO(ZkpEq)
 {
 	sheSecretKey sec;
 	sheSecretKeySetByCSPRNG(&sec);