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spirserver.cc
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spirserver.cc
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// Percy++ Copyright 2007,2012,2013 Ian Goldberg <iang@cs.uwaterloo.ca>,
// Casey Devet <cjdevet@cs.uwaterloo.ca>,
// Paul Hendry <pshdenry@uwaterloo.ca>,
// Ryan Henry <rhenry@cs.uwaterloo.ca>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of version 2 of the GNU General Public License as
// published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// There is a copy of the GNU General Public License in the COPYING file
// packaged with this plugin; if you cannot find it, write to the Free
// Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
// 02110-1301 USA
#include <sstream>
#include <algorithm>
#include "spirserver.h"
SPIRServerQuery::SPIRServerQuery () :
progress(PROGRESS_NONE),
z(true),
cvec_size(0),
cvec(NULL)
{}
SPIRServerQuery::~SPIRServerQuery ()
{
if (cvec != NULL) {
delete[] cvec;
}
}
SPIRServerQuery::SPIRServerQuery (const SPIRServerQuery &other) :
progress(other.progress),
commitvec(other.commitvec), witness(other.witness),
witness_prime(other.witness_prime), a_r(other.a_r), z(other.z),
C_a_prime(other.C_a_prime), D(other.D), D_prime(other.D_prime),
eta_1(other.eta_1), eta_2(other.eta_2), eta_3(other.eta_3),
eta_4(other.eta_4), eta_5(other.eta_5), eta_6(other.eta_6),
v_0(other.v_0), v_1(other.v_1), v_2(other.v_2), v_3(other.v_3),
muvec(other.muvec), nuvec(other.nuvec), chivec(other.chivec),
cvec_size(other.cvec_size), cvec(NULL),
ephemeral_block(other.ephemeral_block), finalshare(other.finalshare)
{
if (cvec_size > 0) {
cvec = new uint64_t[cvec_size];
}
for (dbsize_t i = 0; i < cvec_size; ++i) {
cvec[i] = other.cvec[i];
}
}
SPIRServerQuery& SPIRServerQuery::operator= (SPIRServerQuery other)
{
progress = other.progress;
commitvec = other.commitvec;
witness = other.witness;
witness_prime = other.witness_prime;
a_r = other.a_r;
z = other.z;
C_a_prime = other.C_a_prime;
D = other.D;
D_prime = other.D_prime;
eta_1 = other.eta_1;
eta_2 = other.eta_2;
eta_3 = other.eta_3;
eta_4 = other.eta_4;
eta_5 = other.eta_5;
eta_5 = other.eta_6;
v_0 = other.v_0;
v_1 = other.v_1;
v_2 = other.v_2;
v_3 = other.v_3;
muvec = other.muvec;
nuvec = other.nuvec;
chivec = other.chivec;
cvec_size = other.cvec_size;
std::swap(cvec, other.cvec);
ephemeral_block = other.ephemeral_block;
finalshare = other.finalshare;
return *this;
}
bool SPIRServerQuery::read_spir_input (PercyServerParams ¶ms, std::istream &is)
{
PolyCommitParams * pcparamsp = params.get_pcparamsp();
// Set the appropriate modulus
unsigned int modulus_bytes;
if (params.hybrid()) {
params.mod_modulussq();
modulus_bytes = params.modulussq_bytes();
} else {
params.mod_modulus();
modulus_bytes = params.modulus_bytes();
}
// Read some values from the params
dbsize_t num_blocks = params.num_blocks();
const Pairing &e = pcparamsp->get_pairing();
// Read in the vector of commitments
commitvec.SetLength(num_blocks);
muvec.SetLength(num_blocks);
nuvec.SetLength(num_blocks);
for(unsigned int i = 0; i < num_blocks; ++i) {
commitvec[i] = G1(e);
muvec[i] = G1(e);
nuvec[i] = GT(e);
is >> commitvec[i] >> muvec[i] >> nuvec[i];
if (is.eof()) {
return false;
}
}
// Read in the witness
witness = G1(e);
is >> witness;
if (is.eof()) {
return false;
}
// Read in eta_1,..., eta_6, C_a_prime, witness_prime, D, D_prime
eta_1 = G1(e);
eta_2 = G1(e);
eta_3 = G1(e);
eta_4 = GT(e);
eta_5 = GT(e);
eta_6 = GT(e);
C_a_prime = G1(e);
witness_prime = G1(e);
D = GT(e);
D_prime = GT(e);
is >> eta_1 >> eta_2 >> eta_3 >> eta_4 >> eta_5 >> eta_6
>> C_a_prime >> witness_prime >> D >> D_prime;
if (is.eof()) {
return false;
}
// Read in v_0,...,v_3
unsigned char * vbytes = new unsigned char[4 * modulus_bytes];
is.read((char *)vbytes, 4*modulus_bytes);
if (is.eof()) {
return false;
}
ZZ inputz[4];
for (unsigned int k=0; k<4; k++) {
ZZFromBytes(inputz[k], vbytes + k * modulus_bytes, modulus_bytes);
}
v_0 = to_ZZ_p(inputz[0]);
v_1 = to_ZZ_p(inputz[1]);
v_2 = to_ZZ_p(inputz[2]);
v_3 = to_ZZ_p(inputz[3]);
delete[] vbytes;
// Read in chivec
unsigned char * cbytes = new unsigned char[modulus_bytes];
ZZ cinputz;
chivec.SetLength(num_blocks);
for (dbsize_t i = 0; i < num_blocks; ++i) {
is.read((char *)cbytes, modulus_bytes);
if (is.eof()) {
delete[] cbytes;
return false;
}
ZZFromBytes(cinputz, cbytes, modulus_bytes);
chivec[i] = to_ZZ_p(cinputz);
}
delete[] cbytes;
// Read in cvec
cvec = new uint64_t[num_blocks];
cvec_size = num_blocks;
uint64_t * cvecarr = new uint64_t[num_blocks];
is.read((char *)cvecarr, num_blocks * sizeof(uint64_t));
if (is.eof()) {
delete[] cvecarr;
return false;
}
for (dbsize_t i = 0; i < num_blocks; ++i) {
cvec[i] = cvecarr[i];
}
delete[] cvecarr;
progress = PROGRESS_READ_INPUT;
return true;
}
bool SPIRServerQuery::query_verification (PercyServerParams ¶ms, vec_ZZ_p &inputvector)
{
if (progress < PROGRESS_READ_INPUT) {
return false;
}
PolyCommitParams * pcparamsp = params.get_pcparamsp();
// Read some values from the params
dbsize_t num_blocks = params.num_blocks();
const Pairing &e = pcparamsp->get_pairing();
const G1 &g = pcparamsp->get_galphai(0);
const G2 &ghat = pcparamsp->get_ghatalphai(0);
const G2 &ghatalpha = pcparamsp->get_ghatalphai(1);
const GT gt = e(g, ghat);
const G1 &h = pcparamsp->get_h();
const G1 &halpha = pcparamsp->get_halpha();
const GT ht = e(h, ghat);
const GPP<G1> h_pp(e, h);
const GPP<G1> halpha_pp(e, halpha);
const GPP<GT> gt_pp(e, gt);
const GPP<GT> ht_pp(e, ht);
const GPP<G2> ghat_pp(e, ghat);
// Query verification phase
//Compute avec
uint64_t * avec = new uint64_t[num_blocks];
stringbuf sb1;
iostream hash_stream1(&sb1);
hash_stream1 << commitvec[0];
avec[0] = hash_long(hash_stream1, KAPPA);
for (unsigned int i = 1; i < num_blocks; i++) {
stringbuf sb2;
iostream hash_stream2(&sb2);
hash_stream2 << avec[i-1] << commitvec[i];
avec[i] = hash_long(hash_stream2, KAPPA);
}
a_r = avec[num_blocks-1];
//Compute C_a
G1 C_a = G1(e, 1);
uint64_t mask = ((uint64_t) 1)<<(KAPPA-1);
for (unsigned int k = 0; k < KAPPA; ++k, mask >>= 1) {
C_a = C_a.square();
for (dbsize_t i = 0; i < num_blocks; i++) {
if ((avec[i] & mask)) {
C_a *= commitvec[i];
}
}
}
//Compute rho_a and verify the evaluation
ZZ_p rho_a = dot_product(inputvector, avec);
const Zr ir = to_Zr(e, params.get_sid());
const Zr fir = to_Zr(e, rho_a);
const GT LHS = e(C_a, ghat);
const GT RHS = e(witness, ghatalpha/(ghat^ir)) * e(g, ghat^fir);
if (!(LHS == RHS)) {
std::cerr << "Error: Query verification phase failed." << std::endl;
return false;
}
//Verify query proof phase, part I
const GT Y = e(C_a_prime, ghat) / e(witness_prime, ghatalpha);
stringbuf zeta_sb;
iostream zeta_hash_stream(&zeta_sb);
zeta_hash_stream << Y << eta_1 << eta_2 << eta_3 << eta_4 << eta_5 << eta_6; // << credential;
const ZZ_p zeta = to_ZZ_p(hash_ZZ(zeta_hash_stream));
const Zr zeta_Zr = to_Zr(e, zeta);
const Zr v_0_Zr = to_Zr(e, v_0);
z = (eta_2 == ((h_pp^v_0_Zr) * (eta_1^zeta_Zr)));
if (!z)
{
cerr << "Error: verification of query proof phase (part I, line 1) failed.\n";
delete[] avec;
return false;
}
z = (eta_3 == G1::pow2(e, C_a, v_0_Zr, C_a_prime, zeta_Zr));
if (!z)
{
cerr << "Error: verification of query proof phase (part I, line 2) failed.\n";
delete[] avec;
return false;
}
z = (D == ((gt_pp^to_Zr(e, v_1)) * (ht_pp^to_Zr(e, v_2)) * (eta_4^zeta_Zr)));
if (!z)
{
cerr << "Error: verification of query proof phase (part I, line 3) failed.\n";
delete[] avec;
return false;
}
z = (eta_5 == GT::pow2(e, D, v_0_Zr, D_prime, zeta_Zr));
if (!z)
{
cerr << "Error: verification of query proof phase (part I, line 4) failed.\n";
delete[] avec;
return false;
}
z = (eta_6 == ((ht_pp^to_Zr(e, v_3)) * ((D_prime/Y)^zeta_Zr)));
if (!z)
{
cerr << "Error: verification of query proof phase (part I, line 5) failed.\n";
delete[] avec;
return false;
}
//Verify query proof phase, part II
uint64_t * bvec = new uint64_t[num_blocks];
for(dbsize_t i = 0; i < num_blocks; i++) {
bvec[i] = RandomBits_long(KAPPA);
}
G1 lhs1 = G1(e, 1);
GT lhs2 = GT(e, 1);
uint64_t lhs3 = 0;
ZZ_p rhs_exp1 = to_ZZ_p(0);
ZZ_p rhs1_exp2 = to_ZZ_p(0);
ZZ_p rhs2_exp2 = to_ZZ_p(0);
mask = ((uint64_t) 1)<<(KAPPA-1);
for (unsigned int k = 0; k < KAPPA; ++k, mask >>= 1) {
lhs1 = lhs1.square();
lhs2 = lhs2.square();
for (dbsize_t j = 0; j < num_blocks; ++j)
{
if ((bvec[j] & mask)) {
lhs1 *= muvec[j];
lhs2 *= nuvec[j];
}
}
}
stringbuf c_sb;
iostream c_hash_stream(&c_sb);
for (dbsize_t j = 0; j < num_blocks; ++j)
{
rhs_exp1 += chivec[j] * bvec[j];
rhs1_exp2 += to_ZZ_p(avec[j]) * bvec[j] * cvec[j];
rhs2_exp2 += to_ZZ_p(bvec[j]) * cvec[j];
lhs3 += cvec[j];
c_hash_stream << muvec[j] << nuvec[j];
}
const uint64_t c = hash_long(c_hash_stream, KAPPA);
Zr rhs_exp1_Zr = to_Zr(e, rhs_exp1);
delete[] avec;
delete[] bvec;
z = (lhs1 == ((h_pp^rhs_exp1_Zr) * (eta_1^to_Zr(e, rhs1_exp2))));
if (!z)
{
cerr << "Error: verification of query proof phase (part II, line 1) failed.\n";
return false;
}
z = (lhs2 == ((gt_pp^rhs_exp1_Zr) * (Y^to_Zr(e, rhs2_exp2))));
if (!z)
{
cerr << "Error: verification of query proof phase (part II, line 2) failed.\n";
return false;
}
lhs3 = (lhs3 << (64-KAPPA)) >> (64-KAPPA);
z = (lhs3 == c);
if (!z)
{
cerr << "Error: verification of query proof phase (part II, line 3) failed.\n";
return false;
}
progress = PROGRESS_VERIFICATION;
fprintf(stderr, "Query verified\n");
return true;
}
bool SPIRServerQuery::init_randomization (PercyServerParams ¶ms, unsigned char * prng_seed)
{
if (progress < PROGRESS_VERIFICATION) {
return false;
}
// Read some values from the params
dbsize_t words_per_block = params.words_per_block();
//Set the NTL PRNG seed
for(unsigned int i=0; i<8; i++) {
prng_seed[16+i] = 0xff & (a_r >> (8*i));
}
NTL::SetSeed(ZZFromBytes(prng_seed, 24));
//Compute the ephemeral (r+1)th database record for the query
ephemeral_block.SetLength(words_per_block);
for (unsigned int c = 0; c < words_per_block; c++) {
ephemeral_block[c] = random_ZZ_p();
}
//Compute the final share, a pseudorandom polynomial g where g(0)=0
ZZ_pX randpoly = random_ZZ_pX(params.tau());
SetCoeff(randpoly,0,0);
finalshare = eval(randpoly, to_ZZ_p(params.get_sid()));
progress = PROGRESS_INIT_RANDOM;
return true;
}
bool SPIRServerQuery::randomize_response (vec_ZZ_p &response)
{
if (progress < PROGRESS_INIT_RANDOM) {
return false;
}
// Add randomness to the response vector
response += finalshare * ephemeral_block;
return true;
}