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don't save hashSize and tryNum of secretKey

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MITSUNARI Shigeo 8 years ago
parent 354da256e6
commit f75f29e5ea
2 changed files with 31 additions and 28 deletions
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  1. 55
      include/mcl/bgn.hpp
  2. 4
      test/bgn_test.cpp

55
include/mcl/bgn.hpp
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@ -15,7 +15,6 @@
*/ */
#include <vector> #include <vector>
#include <iosfwd> #include <iosfwd>
#include <cybozu/itoa.hpp>
#ifdef MCL_USE_BN384 #ifdef MCL_USE_BN384
#include <mcl/bn384.hpp> #include <mcl/bn384.hpp>
#else #else
@ -47,7 +46,7 @@ class EcHashTable {
public: public:
EcHashTable() : hashSize(0), tryNum(0) {} EcHashTable() : hashSize(0), tryNum(0) {}
/* /*
compute log_P(xP) for |x| <= hashSize * (tryNum + 1) compute log_P(xP) for |x| <= hashSize * tryNum
*/ */
void init(const G& P, int hashSize, size_t tryNum = 0) void init(const G& P, int hashSize, size_t tryNum = 0)
{ {
@ -120,7 +119,7 @@ public:
} }
/* /*
compute log_P(xP) compute log_P(xP)
call basicLog at most 2 * tryNum + 1 call basicLog at most 2 * tryNum
*/ */
int64_t log(const G& xP) const int64_t log(const G& xP) const
{ {
@ -133,7 +132,7 @@ public:
int64_t posCenter = 0; int64_t posCenter = 0;
int64_t negCenter = 0; int64_t negCenter = 0;
int64_t next = hashSize * 2 + 1; int64_t next = hashSize * 2 + 1;
for (size_t i = 0; i < tryNum; i++) { for (size_t i = 1; i < tryNum; i++) {
posP -= nextP; posP -= nextP;
posCenter += next; posCenter += next;
c = basicLog(posP, &ok); c = basicLog(posP, &ok);
@ -163,7 +162,7 @@ class GTHashTable {
public: public:
GTHashTable() : hashSize(0), tryNum(0) {} GTHashTable() : hashSize(0), tryNum(0) {}
/* /*
compute log_P(g^x) for |x| <= hashSize * (tryNum + 1) compute log_P(g^x) for |x| <= hashSize * tryNum
*/ */
void init(const GT& g, int hashSize, size_t tryNum = 0) void init(const GT& g, int hashSize, size_t tryNum = 0)
{ {
@ -232,7 +231,7 @@ public:
} }
/* /*
compute log_P(g^x) compute log_P(g^x)
call basicLog at most 2 * tryNum + 1 call basicLog at most 2 * tryNum
*/ */
int64_t log(const GT& gx) const int64_t log(const GT& gx) const
{ {
@ -245,7 +244,7 @@ public:
int64_t posCenter = 0; int64_t posCenter = 0;
int64_t negCenter = 0; int64_t negCenter = 0;
int64_t next = hashSize * 2 + 1; int64_t next = hashSize * 2 + 1;
for (size_t i = 0; i < tryNum; i++) { for (size_t i = 1; i < tryNum; i++) {
pos *= nextgInv; pos *= nextgInv;
posCenter += next; posCenter += next;
c = basicLog(pos, &ok); c = basicLog(pos, &ok);
@ -399,13 +398,11 @@ public:
class SecretKey { class SecretKey {
Fr x1, y1, z1; Fr x1, y1, z1;
Fr x2, y2, z2; Fr x2, y2, z2;
size_t hashSize;
size_t tryNum;
G1 B1; // (x1 y1 - z1) P G1 B1; // (x1 y1 - z1) P
G2 B2; // (x2 y2 - z2) Q G2 B2; // (x2 y2 - z2) Q
Fr x1x2; Fr x1x2;
GT g; // e(B1, B2) GT g; // e(B1, B2)
local::EcHashTable<G1> ecHashTbl; local::EcHashTable<G1> g1HashTbl;
local::GTHashTable<GT> gtHashTbl; local::GTHashTable<GT> gtHashTbl;
void initInner() void initInner()
{ {
@ -415,7 +412,6 @@ public:
BN::pairing(g, B1, B2); BN::pairing(g, B1, B2);
} }
public: public:
SecretKey() : hashSize(0), tryNum(0) {}
template<class RG> template<class RG>
void setByCSPRNG(RG& rg) void setByCSPRNG(RG& rg)
{ {
@ -428,16 +424,30 @@ public:
initInner(); initInner();
} }
/* /*
decode message m for |m| <= hasSize * (tryNum + 1) set range for G1-DLP
decode time = O(log(hasSize) * tryNum)
*/ */
void setDecodeRange(size_t hashSize, size_t tryNum = 0) void setRangeForG1DLP(size_t hashSize, size_t tryNum = 0)
{
g1HashTbl.init(B1, hashSize, tryNum);
}
/*
set range for GT-DLP
*/
void setRangeForGTDLP(size_t hashSize, size_t tryNum = 0)
{ {
this->hashSize = hashSize;
this->tryNum = tryNum;
ecHashTbl.init(B1, hashSize, tryNum);
gtHashTbl.init(g, hashSize, tryNum); gtHashTbl.init(g, hashSize, tryNum);
} }
/*
set range for G1/GT DLP
decode message m for |m| <= hasSize * tryNum
decode time = O(log(hasSize) * tryNum)
@note if tryNum = 0 then fast but require more memory(TBD)
*/
void setRangeForDLP(size_t hashSize, size_t tryNum = 0)
{
setRangeForG1DLP(hashSize, tryNum);
setRangeForGTDLP(hashSize, tryNum);
}
/* /*
set (xP, yP, zP) and (xQ, yQ, zQ) set (xP, yP, zP) and (xQ, yQ, zQ)
*/ */
@ -479,7 +489,7 @@ public:
G1 R; G1 R;
G1::mul(R, c.S, x1); G1::mul(R, c.S, x1);
R -= c.T; R -= c.T;
return ecHashTbl.log(R); return g1HashTbl.log(R);
} }
int64_t dec(const CipherTextA& c) const int64_t dec(const CipherTextA& c) const
{ {
@ -523,8 +533,6 @@ public:
x2.readStream(is, ioMode); x2.readStream(is, ioMode);
y2.readStream(is, ioMode); y2.readStream(is, ioMode);
z2.readStream(is, ioMode); z2.readStream(is, ioMode);
is >> hashSize >> tryNum;
setDecodeRange(hashSize, tryNum);
return is; return is;
} }
void getStr(std::string& str, int ioMode = 0) const void getStr(std::string& str, int ioMode = 0) const
@ -541,10 +549,6 @@ public:
str += y2.getStr(ioMode); str += y2.getStr(ioMode);
str += sep; str += sep;
str += z2.getStr(ioMode); str += z2.getStr(ioMode);
str += ' ';
str += cybozu::itoa(hashSize);
str += ' ';
str += cybozu::itoa(tryNum);
} }
void setStr(const std::string& str, int ioMode = 0) void setStr(const std::string& str, int ioMode = 0)
{ {
@ -568,8 +572,7 @@ public:
bool operator==(const SecretKey& rhs) const bool operator==(const SecretKey& rhs) const
{ {
return x1 == rhs.x1 && y1 == rhs.y1 && z1 == rhs.z1 return x1 == rhs.x1 && y1 == rhs.y1 && z1 == rhs.z1
&& x2 == rhs.x2 && y2 == rhs.y2 && z2 == rhs.z2 && x2 == rhs.x2 && y2 == rhs.y2 && z2 == rhs.z2;
&& hashSize == rhs.hashSize && tryNum == rhs.tryNum;
} }
bool operator!=(const SecretKey& rhs) const { return !operator==(rhs); } bool operator!=(const SecretKey& rhs) const { return !operator==(rhs); }
}; };

4
test/bgn_test.cpp
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@ -88,7 +88,7 @@ CYBOZU_TEST_AUTO(enc_dec)
{ {
SecretKey& sec = g_sec; SecretKey& sec = g_sec;
sec.setByCSPRNG(rg); sec.setByCSPRNG(rg);
sec.setDecodeRange(1024); sec.setRangeForDLP(1024);
PublicKey pub; PublicKey pub;
sec.getPublicKey(pub); sec.getPublicKey(pub);
CipherText c; CipherText c;
@ -182,7 +182,7 @@ CYBOZU_TEST_AUTO(io)
} }
SecretKey sec; SecretKey sec;
sec.setByCSPRNG(rg); sec.setByCSPRNG(rg);
sec.setDecodeRange(100, 2); sec.setRangeForDLP(100, 2);
testIo(sec); testIo(sec);
PublicKey pub; PublicKey pub;
sec.getPublicKey(pub); sec.getPublicKey(pub);

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