ringct: do not serialize what can be reconstructed

The mixRing (output keys and commitments) and II fields (key images)
can be reconstructed from vin data.
This saves some modest amount of space in the tx.
This commit is contained in:
moneromooo-monero 2016-06-29 18:18:18 +01:00
parent 106e3dc3d4
commit 20e50ec7f7
No known key found for this signature in database
GPG key ID: 686F07454D6CEFC3
8 changed files with 148 additions and 74 deletions

View file

@ -2461,6 +2461,13 @@ bool Blockchain::check_tx_inputs(const transaction& tx, tx_verification_context
else
{
// from version 2, check ringct signatures
rct::ctkeyM reconstructed_mixRing;
rct::keyV reconstructed_II;
// if the tx already has a non empty mixRing and/or II, use them,
// else reconstruct them
const rct::ctkeyM &mixRing = tx.rct_signatures.mixRing.empty() ? reconstructed_mixRing : tx.rct_signatures.mixRing;
const rct::keyV &II = tx.rct_signatures.MG.II.size() == 1 ? reconstructed_II : tx.rct_signatures.MG.II;
// RCT needs the same mixin for all inputs
for (size_t n = 1; n < pubkeys.size(); ++n)
@ -2472,35 +2479,74 @@ bool Blockchain::check_tx_inputs(const transaction& tx, tx_verification_context
}
}
bool size_matches = true;
for (size_t i = 0; i < pubkeys.size(); ++i)
size_matches &= pubkeys[i].size() == tx.rct_signatures.mixRing.size();
for (size_t i = 0; i < tx.rct_signatures.mixRing.size(); ++i)
size_matches &= pubkeys.size() == tx.rct_signatures.mixRing[i].size();
if (!size_matches)
if (tx.rct_signatures.mixRing.empty())
{
LOG_PRINT_L1("Failed to check ringct signatures: mismatched pubkeys/mixRing size");
return false;
}
for (size_t n = 0; n < pubkeys.size(); ++n)
{
for (size_t m = 0; m < pubkeys[n].size(); ++m)
reconstructed_mixRing.resize(pubkeys[0].size());
for (size_t n = 0; n < pubkeys.size(); ++n)
{
if (pubkeys[n][m].dest != rct::rct2pk(tx.rct_signatures.mixRing[m][n].dest))
for (size_t m = 0; m < pubkeys[n].size(); ++m)
{
LOG_PRINT_L1("Failed to check ringct signatures: mismatched pubkey at vin " << n << ", index " << m);
return false;
}
if (pubkeys[n][m].mask != rct::rct2pk(tx.rct_signatures.mixRing[m][n].mask))
{
LOG_PRINT_L1("Failed to check ringct signatures: mismatched commitment at vin " << n << ", index " << m);
return false;
reconstructed_mixRing[m].push_back(pubkeys[n][m]);
}
}
}
if (!rct::verRct(tx.rct_signatures))
if (tx.rct_signatures.MG.II.size() == 1)
{
reconstructed_II.resize(tx.vin.size());
for (size_t n = 0; n < tx.vin.size(); ++n)
{
reconstructed_II[n] = rct::ki2rct(boost::get<txin_to_key>(tx.vin[n]).k_image);
}
reconstructed_II.push_back(tx.rct_signatures.MG.II.back());
}
// check all this, either recontructed (so should really pass), or not
{
bool size_matches = true;
for (size_t i = 0; i < pubkeys.size(); ++i)
size_matches &= pubkeys[i].size() == mixRing.size();
for (size_t i = 0; i < tx.rct_signatures.mixRing.size(); ++i)
size_matches &= pubkeys.size() == mixRing[i].size();
if (!size_matches)
{
LOG_PRINT_L1("Failed to check ringct signatures: mismatched pubkeys/mixRing size");
return false;
}
for (size_t n = 0; n < pubkeys.size(); ++n)
{
for (size_t m = 0; m < pubkeys[n].size(); ++m)
{
if (pubkeys[n][m].dest != rct::rct2pk(mixRing[m][n].dest))
{
LOG_PRINT_L1("Failed to check ringct signatures: mismatched pubkey at vin " << n << ", index " << m);
return false;
}
if (pubkeys[n][m].mask != rct::rct2pk(mixRing[m][n].mask))
{
LOG_PRINT_L1("Failed to check ringct signatures: mismatched commitment at vin " << n << ", index " << m);
return false;
}
}
}
}
if (II.size() != 1 + tx.vin.size())
{
LOG_PRINT_L1("Failed to check ringct signatures: mismatched II/vin sizes");
return false;
}
for (size_t n = 0; n < tx.vin.size(); ++n)
{
if (memcmp(&boost::get<txin_to_key>(tx.vin[n]).k_image, &II[n], 32))
{
LOG_PRINT_L1("Failed to check ringct signatures: mismatched II/vin sizes");
return false;
}
}
if (!rct::verRct(tx.rct_signatures, mixRing, II, rct::hash2rct(tx_prefix_hash)))
{
LOG_PRINT_L1("Failed to check ringct signatures!");
return false;
@ -2613,7 +2659,8 @@ bool Blockchain::check_tx_input(size_t tx_version, const txin_to_key& txin, cons
}
else
{
CHECK_AND_ASSERT_MES(rct_signatures.mixRing.size() == output_keys.size(), false, "internal error: tx rct signatures count=" << sig.size() << " mismatch with outputs keys count for inputs=" << output_keys.size());
// rct signatures may be empty (and will be reconstructed later in the caller if so)
CHECK_AND_ASSERT_MES(rct_signatures.mixRing.empty() || rct_signatures.mixRing.size() == output_keys.size(), false, "internal error: tx rct signatures count=" << sig.size() << " mismatch with outputs keys count for inputs=" << output_keys.size());
}
return true;
}

View file

@ -37,6 +37,8 @@
#include <boost/serialization/map.hpp>
#include <boost/foreach.hpp>
#include <boost/serialization/is_bitwise_serializable.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include "cryptonote_basic.h"
#include "common/unordered_containers_boost_serialization.h"
#include "crypto/crypto.h"
@ -196,12 +198,19 @@ namespace boost
a & x.s;
}
template <class Archive>
inline void serialize(Archive &a, rct::mgSig &x, const boost::serialization::version_type ver)
inline void serialize(boost::archive::binary_iarchive &a, rct::mgSig &x, const boost::serialization::version_type ver)
{
a & x.ss;
a & x.cc;
a & x.II;
x.II.resize(1);
a & x.II[0];
}
inline void serialize(boost::archive::binary_oarchive &a, rct::mgSig &x, const boost::serialization::version_type ver)
{
a & x.ss;
a & x.cc;
a & x.II.back();
}
template <class Archive>
@ -217,10 +226,11 @@ namespace boost
{
a & x.rangeSigs;
a & x.MG;
a & x.mixRing;
// a & x.mixRing; mixRing is not serialized, as it can be reconstructed from the offsets
a & x.ecdhInfo;
a & x.outPk;
a & x.txnFee;
// a & x.bash_hash; bash_hash is not serialized, as it can be reconstructed from the tx data
}
}
}

View file

@ -226,7 +226,7 @@ namespace rct {
// Gen creates a signature which proves that for some column in the keymatrix "pk"
// the signer knows a secret key for each row in that column
// Ver verifies that the MG sig was created correctly
bool MLSAG_Ver(key message, const keyM & pk, const mgSig & rv) {
bool MLSAG_Ver(key message, const keyM & pk, const mgSig & rv, const keyV &II) {
size_t cols = pk.size();
CHECK_AND_ASSERT_MES(cols >= 2, false, "Error! What is c if cols = 1!");
@ -235,7 +235,7 @@ namespace rct {
for (size_t i = 1; i < cols; ++i) {
CHECK_AND_ASSERT_MES(pk[i].size() == rows, false, "pk is not rectangular");
}
CHECK_AND_ASSERT_MES(rv.II.size() == rows, false, "Bad rv.II size");
CHECK_AND_ASSERT_MES(II.size() == rows, false, "Bad II size");
CHECK_AND_ASSERT_MES(rv.ss.size() == cols, false, "Bad rv.ss size");
for (size_t i = 0; i < cols; ++i) {
CHECK_AND_ASSERT_MES(rv.ss[i].size() == rows, false, "rv.ss is not rectangular");
@ -246,7 +246,7 @@ namespace rct {
key c_old = copy(rv.cc);
vector<geDsmp> Ip(rows);
for (i= 0 ; i< rows ; i++) {
precomp(Ip[i].k, rv.II[i]);
precomp(Ip[i].k, II[i]);
}
unsigned char m2[128];
memcpy(m2, message.bytes, 32);
@ -334,7 +334,7 @@ namespace rct {
// this shows that sum inputs = sum outputs
//Ver:
// verifies the above sig is created corretly
mgSig proveRctMG(const ctkeyM & pubs, const ctkeyV & inSk, const ctkeyV &outSk, const ctkeyV & outPk, unsigned int index, key txnFeeKey) {
mgSig proveRctMG(const ctkeyM & pubs, const ctkeyV & inSk, const ctkeyV &outSk, const ctkeyV & outPk, unsigned int index, key txnFeeKey, const key &base_hash) {
mgSig mg;
//setup vars
size_t cols = pubs.size();
@ -378,7 +378,9 @@ namespace rct {
for (size_t j = 0; j < outPk.size(); j++) {
sc_sub(sk[rows].bytes, sk[rows].bytes, outSk[j].mask.bytes); //subtract output masks in last row..
}
key message = cn_fast_hash(outPk);
ctkeyV signed_data = outPk;
signed_data.push_back(ctkey({base_hash, identity()}));
key message = cn_fast_hash(signed_data);
return MLSAG_Gen(message, M, sk, index);
}
@ -391,7 +393,7 @@ namespace rct {
// this shows that sum inputs = sum outputs
//Ver:
// verifies the above sig is created corretly
bool verRctMG(mgSig mg, const ctkeyM & pubs, const ctkeyV & outPk, key txnFeeKey) {
bool verRctMG(mgSig mg, const keyV &II, const ctkeyM & pubs, const ctkeyV & outPk, key txnFeeKey, const key &base_hash) {
//setup vars
size_t cols = pubs.size();
CHECK_AND_ASSERT_MES(cols >= 1, false, "Empty pubs");
@ -422,10 +424,12 @@ namespace rct {
//subtract txn fee output in last row
subKeys(M[i][rows], M[i][rows], txnFeeKey);
}
key message = cn_fast_hash(outPk);
ctkeyV signed_data = outPk;
signed_data.push_back(ctkey({base_hash, identity()}));
key message = cn_fast_hash(signed_data);
DP("message:");
DP(message);
return MLSAG_Ver(message, M, mg);
return MLSAG_Ver(message, M, mg, II);
}
//These functions get keys from blockchain
@ -470,7 +474,7 @@ namespace rct {
// must know the destination private key to find the correct amount, else will return a random number
// Note: For txn fees, the last index in the amounts vector should contain that
// Thus the amounts vector will be "one" longer than the destinations vectort
rctSig genRct(const ctkeyV & inSk, const keyV & destinations, const vector<xmr_amount> amounts, const ctkeyM &mixRing, unsigned int index) {
rctSig genRct(const ctkeyV & inSk, const keyV & destinations, const vector<xmr_amount> amounts, const ctkeyM &mixRing, const key &base_hash, unsigned int index) {
CHECK_AND_ASSERT_THROW_MES(amounts.size() == destinations.size() || amounts.size() == destinations.size() + 1, "Different number of amounts/destinations");
CHECK_AND_ASSERT_THROW_MES(index < mixRing.size(), "Bad index into mixRing");
for (size_t n = 0; n < mixRing.size(); ++n) {
@ -513,15 +517,16 @@ namespace rct {
key txnFeeKey = scalarmultH(d2h(rv.txnFee));
rv.mixRing = mixRing;
rv.MG = proveRctMG(rv.mixRing, inSk, outSk, rv.outPk, index, txnFeeKey);
rv.base_hash = base_hash;
rv.MG = proveRctMG(rv.mixRing, inSk, outSk, rv.outPk, index, txnFeeKey, base_hash);
return rv;
}
rctSig genRct(const ctkeyV & inSk, const ctkeyV & inPk, const keyV & destinations, const vector<xmr_amount> amounts, const int mixin) {
rctSig genRct(const ctkeyV & inSk, const ctkeyV & inPk, const keyV & destinations, const vector<xmr_amount> amounts, const key &base_hash, const int mixin) {
unsigned int index;
ctkeyM mixRing;
tie(mixRing, index) = populateFromBlockchain(inPk, mixin);
return genRct(inSk, destinations, amounts, mixRing, index);
return genRct(inSk, destinations, amounts, mixRing, base_hash, index);
}
//RingCT protocol
@ -534,7 +539,7 @@ namespace rct {
//decodeRct: (c.f. http://eprint.iacr.org/2015/1098 section 5.1.1)
// uses the attached ecdh info to find the amounts represented by each output commitment
// must know the destination private key to find the correct amount, else will return a random number
bool verRct(const rctSig & rv) {
bool verRct(const rctSig & rv, const ctkeyM &mixRing, const keyV &II, const key &base_hash) {
CHECK_AND_ASSERT_MES(rv.outPk.size() == rv.rangeSigs.size(), false, "Mismatched sizes of rv.outPk and rv.rangeSigs");
CHECK_AND_ASSERT_MES(rv.outPk.size() == rv.ecdhInfo.size(), false, "Mismatched sizes of rv.outPk and rv.ecdhInfo");
@ -552,7 +557,7 @@ namespace rct {
}
//compute txn fee
key txnFeeKey = scalarmultH(d2h(rv.txnFee));
bool mgVerd = verRctMG(rv.MG, rv.mixRing, rv.outPk, txnFeeKey);
bool mgVerd = verRctMG(rv.MG, II, mixRing, rv.outPk, txnFeeKey, base_hash);
DP("mg sig verified?");
DP(mgVerd);
@ -563,6 +568,9 @@ namespace rct {
return false;
}
}
bool verRct(const rctSig & rv) {
return verRct(rv, rv.mixRing, rv.MG.II, rv.base_hash);
}
//RingCT protocol
//genRct:

View file

@ -91,7 +91,7 @@ namespace rct {
// Ver verifies that the MG sig was created correctly
keyV keyImageV(const keyV &xx);
mgSig MLSAG_Gen(key message, const keyM & pk, const keyV & xx, const unsigned int index);
bool MLSAG_Ver(key message, const keyM &pk, const mgSig &sig);
bool MLSAG_Ver(key message, const keyM &pk, const mgSig &sig, const keyV &II);
//mgSig MLSAG_Gen_Old(const keyM & pk, const keyV & xx, const int index);
//proveRange and verRange
@ -112,8 +112,8 @@ namespace rct {
// this shows that sum inputs = sum outputs
//Ver:
// verifies the above sig is created corretly
mgSig proveRctMG(const ctkeyM & pubs, const ctkeyV & inSk, const keyV &outMasks, const ctkeyV & outPk, unsigned int index, key txnFee);
bool verRctMG(mgSig mg, const ctkeyM & pubs, const ctkeyV & outPk, key txnFee);
mgSig proveRctMG(const ctkeyM & pubs, const ctkeyV & inSk, const keyV &outMasks, const ctkeyV & outPk, unsigned int index, key txnFee, const key &base_hash);
bool verRctMG(mgSig mg, const ctkeyM & pubs, const ctkeyV & outPk, key txnFee, const key &base_hash);
//These functions get keys from blockchain
//replace these when connecting blockchain
@ -133,9 +133,10 @@ namespace rct {
//decodeRct: (c.f. http://eprint.iacr.org/2015/1098 section 5.1.1)
// uses the attached ecdh info to find the amounts represented by each output commitment
// must know the destination private key to find the correct amount, else will return a random number
rctSig genRct(const ctkeyV & inSk, const keyV & destinations, const vector<xmr_amount> amounts, const ctkeyM &mixRing, unsigned int index);
rctSig genRct(const ctkeyV & inSk, const ctkeyV & inPk, const keyV & destinations, const vector<xmr_amount> amounts, const int mixin);
rctSig genRct(const ctkeyV & inSk, const keyV & destinations, const vector<xmr_amount> amounts, const ctkeyM &mixRing, const key &bash_hash, unsigned int index);
rctSig genRct(const ctkeyV & inSk, const ctkeyV & inPk, const keyV & destinations, const vector<xmr_amount> amounts, const key &bash_hash, const int mixin);
bool verRct(const rctSig & rv);
bool verRct(const rctSig & rv, const ctkeyM &mixRing, const keyV &II, const key &base_hash);
xmr_amount decodeRct(const rctSig & rv, const key & sk, unsigned int i, key & mask);
xmr_amount decodeRct(const rctSig & rv, const key & sk, unsigned int i);

View file

@ -148,7 +148,16 @@ namespace rct {
BEGIN_SERIALIZE_OBJECT()
FIELD(ss)
FIELD(cc)
FIELD(II)
if (II.size() == 0) {
// loading
FIELD(II)
}
else {
// saving
keyV II;
II.push_back(this->II.back());
FIELD(II)
}
END_SERIALIZE()
};
//contains the data for an asnl sig
@ -181,14 +190,16 @@ namespace rct {
vector<ecdhTuple> ecdhInfo;
ctkeyV outPk;
xmr_amount txnFee;
key base_hash;
BEGIN_SERIALIZE_OBJECT()
FIELD(rangeSigs)
FIELD(MG)
FIELD(mixRing)
// FIELD(mixRing) - not serialized, it can be reconstructed
FIELD(ecdhInfo)
FIELD(outPk)
FIELD(txnFee)
// FIELD(base_hash) - not serialized, it can be reconstructed
END_SERIALIZE()
};
@ -296,9 +307,11 @@ namespace rct {
static inline rct::key pk2rct(const crypto::public_key &pk) { rct::key k; memcpy(&k, &pk, 32); return k; }
static inline rct::key sk2rct(const crypto::secret_key &sk) { rct::key k; memcpy(&k, &sk, 32); return k; }
static inline rct::key ki2rct(const crypto::key_image &ki) { rct::key k; memcpy(&k, &ki, 32); return k; }
static inline rct::key hash2rct(const crypto::hash &h) { rct::key k; memcpy(&k, &h, 32); return k; }
static inline crypto::public_key rct2pk(const rct::key &k) { crypto::public_key pk; memcpy(&pk, &k, 32); return pk; }
static inline crypto::secret_key rct2sk(const rct::key &k) { crypto::secret_key sk; memcpy(&sk, &k, 32); return sk; }
static inline crypto::key_image rct2ki(const rct::key &k) { crypto::key_image ki; memcpy(&ki, &k, 32); return ki; }
static inline crypto::hash rct2hash(const rct::key &k) { crypto::hash h; memcpy(&h, &k, 32); return h; }
static inline bool operator==(const rct::key &k0, const crypto::public_key &k1) { return !memcmp(&k0, &k1, 32); }
static inline bool operator!=(const rct::key &k0, const crypto::public_key &k1) { return memcmp(&k0, &k1, 32); }
}

View file

@ -3237,16 +3237,19 @@ static size_t estimate_rct_tx_size(int n_inputs, int mixin, int n_outputs)
// rangeSigs
size += (2*64*32+32+64*32) * n_outputs;
// MG
size += 32 * (mixin+1) * n_inputs + 32 + 32 * n_inputs;
// mixRing
size += 2 * 32 * (mixin+1) * n_inputs;
// MG - only the last slot of II is saved, the rest can be reconstructed
size += 32 * (mixin+1) * n_inputs + 32 + 32 * (/*n_inputs+*/1) ;
// mixRing - not serialized, can be reconstructed
/* size += 2 * 32 * (mixin+1) * n_inputs; */
// ecdhInfo
size += 3 * 32 * n_outputs;
// outPk
size += 2 * 32 * n_outputs;
LOG_PRINT_L2("estimated rct tx size for " << n_inputs << " at mixin " << mixin << " and " << n_outputs << ": " << size);
LOG_PRINT_L2("estimated rct tx size for " << n_inputs << " at mixin " << mixin << " and " << n_outputs << ": " << size << " (" << (32 * n_inputs + 2 * 32 * (mixin+1) * n_inputs) << " saved)");
return size;
}

View file

@ -131,7 +131,7 @@ TEST(ringct, MG_sigs)
}
key message = identity();
mgSig IIccss = MLSAG_Gen(message, P, sk, ind);
ASSERT_TRUE(MLSAG_Ver(message, P, IIccss));
ASSERT_TRUE(MLSAG_Ver(message, P, IIccss, IIccss.II));
//#MG sig: false one
N = 3;// #cols
@ -152,7 +152,7 @@ TEST(ringct, MG_sigs)
}
sk[2] = skGen();//asume we don't know one of the private keys..
IIccss = MLSAG_Gen(message, P, sk, ind);
ASSERT_FALSE(MLSAG_Ver(message, P, IIccss));
ASSERT_FALSE(MLSAG_Ver(message, P, IIccss, IIccss.II));
}
TEST(ringct, range_proofs)

View file

@ -576,11 +576,10 @@ TEST(Serialization, serializes_ringct_types)
ASSERT_TRUE(mg0.ss[n] == mg1.ss[n]);
}
ASSERT_TRUE(mg0.cc == mg1.cc);
ASSERT_TRUE(mg0.II.size() == mg1.II.size());
for (size_t n = 0; n < mg0.II.size(); ++n)
{
ASSERT_TRUE(mg0.II[n] == mg1.II[n]);
}
// mixRing and II are not serialized, they are meant to be reconstructed
ASSERT_TRUE(mg1.II.size() == 1);
ASSERT_TRUE(mg1.II[0] == mg0.II.back());
rg0 = s0.rangeSigs.front();
ASSERT_TRUE(serialization::dump_binary(rg0, blob));
@ -600,20 +599,13 @@ TEST(Serialization, serializes_ringct_types)
ASSERT_TRUE(s0.MG.ss[n] == s1.MG.ss[n]);
}
ASSERT_TRUE(s0.MG.cc == s1.MG.cc);
ASSERT_TRUE(s0.MG.II.size() == s1.MG.II.size());
for (size_t n = 0; n < s0.MG.II.size(); ++n)
{
ASSERT_TRUE(s0.MG.II[n] == s1.MG.II[n]);
}
ASSERT_TRUE(s0.mixRing.size() == s1.mixRing.size());
for (size_t n = 0; n < s0.mixRing.size(); ++n)
{
ASSERT_TRUE(s0.mixRing[n].size() == s1.mixRing[n].size());
for (size_t i = 0; i < s0.mixRing[n].size(); ++i)
{
ASSERT_TRUE(!memcmp(&s0.mixRing[n][i], &s1.mixRing[n][i], sizeof(s0.mixRing[n][i])));
}
}
// mixRing and II are not serialized, they are meant to be reconstructed
ASSERT_TRUE(s1.MG.II.size() == 1);
ASSERT_TRUE(s1.MG.II[0] == s0.MG.II.back());
// mixRing and II are not serialized, they are meant to be reconstructed
ASSERT_TRUE(s1.mixRing.size() == 0);
ASSERT_TRUE(s0.ecdhInfo.size() == s1.ecdhInfo.size());
for (size_t n = 0; n < s0.ecdhInfo.size(); ++n)
{