diff options
Diffstat (limited to 'fp_pub.c')
| -rw-r--r-- | fp_pub.c | 690 |
1 files changed, 352 insertions, 338 deletions
@@ -32,97 +32,97 @@ void fp_pub_prep_outcome (struct BRANDT_Auction *ad) { - gcry_mpi_t coeff = gcry_mpi_copy (GCRYMPI_CONST_ONE); - gcry_mpi_point_t tmp = gcry_mpi_point_new (0); - gcry_mpi_point_t *tlta1; - gcry_mpi_point_t *tltb1; - gcry_mpi_point_t **tlta2; - gcry_mpi_point_t **tltb2; - - ad->gamma2 = smc_init2 (ad->n, ad->k); - brandt_assert (ad->gamma2); - - ad->delta2 = smc_init2 (ad->n, ad->k); - brandt_assert (ad->delta2); - - ad->tmpa1 = smc_init1 (ad->k); - brandt_assert (ad->tmpa1); - - ad->tmpb1 = smc_init1 (ad->k); - brandt_assert (ad->tmpb1); - - /* create temporary lookup tables with partial sums */ - tlta1 = smc_init1 (ad->k); - tltb1 = smc_init1 (ad->k); - tlta2 = smc_init2 (ad->n, ad->k); - tltb2 = smc_init2 (ad->n, ad->k); - - /* temporary lookup table for sum of bid vectors */ - for (uint16_t i = 0; i < ad->n; i++) - { - smc_sums_partial (tlta2[i], ad->alpha[i], ad->k, 1, 1); - smc_sums_partial (tltb2[i], ad->beta[i], ad->k, 1, 1); - for (uint16_t j = 0; j < ad->k; j++) - { - gcry_mpi_ec_sub (tlta2[i][j], - tlta2[i][ad->k - 1], - tlta2[i][j], - ec_ctx); - gcry_mpi_ec_sub (tltb2[i][j], - tltb2[i][ad->k - 1], - tltb2[i][j], - ec_ctx); - } - brandt_assert (!ec_point_cmp (ec_zero, tlta2[i][ad->k - 1])); - brandt_assert (!ec_point_cmp (ec_zero, tltb2[i][ad->k - 1])); - } - for (uint16_t j = 0; j < ad->k; j++) - { - smc_sum (tlta1[j], &tlta2[0][j], ad->n, ad->k); - smc_sum (tltb1[j], &tltb2[0][j], ad->n, ad->k); - } - smc_free2 (tlta2, ad->n, ad->k); - smc_free2 (tltb2, ad->n, ad->k); - brandt_assert (!ec_point_cmp (ec_zero, tlta1[ad->k - 1])); - brandt_assert (!ec_point_cmp (ec_zero, tltb1[ad->k - 1])); - - /* initialize tmp array with zeroes, since we are calculating a sum */ - for (uint16_t j = 0; j < ad->k; j++) - { - ec_point_copy (ad->tmpa1[j], ec_zero); - ec_point_copy (ad->tmpb1[j], ec_zero); - } - /* store the \sum_{i=1}^n2^{i-1}b_i in tmp1 until outcome determination, - * since it is needed each time a gamma,delta pair is received from another - * bidder */ - for (uint16_t i = 0; i < ad->n; i++) - { - for (uint16_t j = 0; j < ad->k; j++) - { - gcry_mpi_ec_mul (tmp, coeff, ad->alpha[i][j], ec_ctx); - gcry_mpi_ec_add (ad->tmpa1[j], ad->tmpa1[j], tmp, ec_ctx); - gcry_mpi_ec_mul (tmp, coeff, ad->beta[i][j], ec_ctx); - gcry_mpi_ec_add (ad->tmpb1[j], ad->tmpb1[j], tmp, ec_ctx); - } - gcry_mpi_lshift (coeff, coeff, 1); - } - - for (uint16_t j = 0; j < ad->k; j++) - { - /* copy unmasked outcome to all other bidder layers so they don't - * have to be recomputed to check the ZK proof_2dle's from other - * bidders when receiving their outcome messages */ - for (uint16_t a = 0; a < ad->n; a++) - { - ec_point_copy (ad->gamma2[a][j], tlta1[j]); - ec_point_copy (ad->delta2[a][j], tltb1[j]); - } - } - - gcry_mpi_release (coeff); - gcry_mpi_point_release (tmp); - smc_free1 (tlta1, ad->k); - smc_free1 (tltb1, ad->k); + gcry_mpi_t coeff = gcry_mpi_copy (GCRYMPI_CONST_ONE); + gcry_mpi_point_t tmp = gcry_mpi_point_new (0); + gcry_mpi_point_t *tlta1; + gcry_mpi_point_t *tltb1; + gcry_mpi_point_t **tlta2; + gcry_mpi_point_t **tltb2; + + ad->gamma2 = smc_init2 (ad->n, ad->k); + brandt_assert (ad->gamma2); + + ad->delta2 = smc_init2 (ad->n, ad->k); + brandt_assert (ad->delta2); + + ad->tmpa1 = smc_init1 (ad->k); + brandt_assert (ad->tmpa1); + + ad->tmpb1 = smc_init1 (ad->k); + brandt_assert (ad->tmpb1); + + /* create temporary lookup tables with partial sums */ + tlta1 = smc_init1 (ad->k); + tltb1 = smc_init1 (ad->k); + tlta2 = smc_init2 (ad->n, ad->k); + tltb2 = smc_init2 (ad->n, ad->k); + + /* temporary lookup table for sum of bid vectors */ + for (uint16_t i = 0; i < ad->n; i++) + { + smc_sums_partial (tlta2[i], ad->alpha[i], ad->k, 1, 1); + smc_sums_partial (tltb2[i], ad->beta[i], ad->k, 1, 1); + for (uint16_t j = 0; j < ad->k; j++) + { + gcry_mpi_ec_sub (tlta2[i][j], + tlta2[i][ad->k - 1], + tlta2[i][j], + ec_ctx); + gcry_mpi_ec_sub (tltb2[i][j], + tltb2[i][ad->k - 1], + tltb2[i][j], + ec_ctx); + } + brandt_assert (! ec_point_cmp (ec_zero, tlta2[i][ad->k - 1])); + brandt_assert (! ec_point_cmp (ec_zero, tltb2[i][ad->k - 1])); + } + for (uint16_t j = 0; j < ad->k; j++) + { + smc_sum (tlta1[j], &tlta2[0][j], ad->n, ad->k); + smc_sum (tltb1[j], &tltb2[0][j], ad->n, ad->k); + } + smc_free2 (tlta2, ad->n, ad->k); + smc_free2 (tltb2, ad->n, ad->k); + brandt_assert (! ec_point_cmp (ec_zero, tlta1[ad->k - 1])); + brandt_assert (! ec_point_cmp (ec_zero, tltb1[ad->k - 1])); + + /* initialize tmp array with zeroes, since we are calculating a sum */ + for (uint16_t j = 0; j < ad->k; j++) + { + ec_point_copy (ad->tmpa1[j], ec_zero); + ec_point_copy (ad->tmpb1[j], ec_zero); + } + /* store the \sum_{i=1}^n2^{i-1}b_i in tmp1 until outcome determination, + * since it is needed each time a gamma,delta pair is received from another + * bidder */ + for (uint16_t i = 0; i < ad->n; i++) + { + for (uint16_t j = 0; j < ad->k; j++) + { + gcry_mpi_ec_mul (tmp, coeff, ad->alpha[i][j], ec_ctx); + gcry_mpi_ec_add (ad->tmpa1[j], ad->tmpa1[j], tmp, ec_ctx); + gcry_mpi_ec_mul (tmp, coeff, ad->beta[i][j], ec_ctx); + gcry_mpi_ec_add (ad->tmpb1[j], ad->tmpb1[j], tmp, ec_ctx); + } + gcry_mpi_lshift (coeff, coeff, 1); + } + + for (uint16_t j = 0; j < ad->k; j++) + { + /* copy unmasked outcome to all other bidder layers so they don't + * have to be recomputed to check the ZK proof_2dle's from other + * bidders when receiving their outcome messages */ + for (uint16_t a = 0; a < ad->n; a++) + { + ec_point_copy (ad->gamma2[a][j], tlta1[j]); + ec_point_copy (ad->delta2[a][j], tltb1[j]); + } + } + + gcry_mpi_release (coeff); + gcry_mpi_point_release (tmp); + smc_free1 (tlta1, ad->k); + smc_free1 (tltb1, ad->k); } @@ -139,149 +139,149 @@ fp_pub_prep_outcome (struct BRANDT_Auction *ad) unsigned char * fp_pub_compute_outcome (struct BRANDT_Auction *ad, size_t *buflen) { - unsigned char *ret; - unsigned char *cur; - gcry_mpi_point_t tmpa = gcry_mpi_point_new (0); - gcry_mpi_point_t tmpb = gcry_mpi_point_new (0); - struct msg_head *head; - struct ec_mpi *gamma; - struct ec_mpi *delta; - struct proof_2dle *proof2; - - brandt_assert (ad && buflen); - - *buflen = (sizeof (*head) + - ad->k * (sizeof (*gamma) + - sizeof (*delta) + - sizeof (*proof2))); - ret = GNUNET_new_array (*buflen, unsigned char); - - head = (struct msg_head *)ret; - head->prot_version = htonl (0); - head->msg_type = htonl (msg_outcome); - cur = ret + sizeof (*head); - - for (uint16_t j = 0; j < ad->k; j++) - { - gamma = (struct ec_mpi *)cur; - delta = &((struct ec_mpi *)cur)[1]; - proof2 = (struct proof_2dle *)(cur + 2 * sizeof (struct ec_mpi)); - - ec_point_copy (tmpa, ad->gamma2[ad->i][j]); - ec_point_copy (tmpb, ad->delta2[ad->i][j]); - - /* apply random masking to first summand */ - smc_zkp_2dle (ad->gamma2[ad->i][j], - ad->delta2[ad->i][j], - tmpa, - tmpb, - NULL, - proof2); - - ec_point_serialize (gamma, ad->gamma2[ad->i][j]); - ec_point_serialize (delta, ad->delta2[ad->i][j]); - - /* add winner determination for own gamma,delta */ - gcry_mpi_ec_add (ad->gamma2[ad->i][j], - ad->gamma2[ad->i][j], - ad->tmpa1[j], - ec_ctx); - gcry_mpi_ec_add (ad->delta2[ad->i][j], - ad->delta2[ad->i][j], - ad->tmpb1[j], - ec_ctx); - - cur += sizeof (*gamma) + sizeof (*delta) + sizeof (*proof2); - } - - gcry_mpi_point_release (tmpa); - gcry_mpi_point_release (tmpb); - return ret; + unsigned char *ret; + unsigned char *cur; + gcry_mpi_point_t tmpa = gcry_mpi_point_new (0); + gcry_mpi_point_t tmpb = gcry_mpi_point_new (0); + struct msg_head *head; + struct ec_mpi *gamma; + struct ec_mpi *delta; + struct proof_2dle *proof2; + + brandt_assert (ad && buflen); + + *buflen = (sizeof (*head) + + ad->k * (sizeof (*gamma) + + sizeof (*delta) + + sizeof (*proof2))); + ret = GNUNET_new_array (*buflen, unsigned char); + + head = (struct msg_head *) ret; + head->prot_version = htonl (0); + head->msg_type = htonl (msg_outcome); + cur = ret + sizeof (*head); + + for (uint16_t j = 0; j < ad->k; j++) + { + gamma = (struct ec_mpi *) cur; + delta = &((struct ec_mpi *) cur)[1]; + proof2 = (struct proof_2dle *) (cur + 2 * sizeof (struct ec_mpi)); + + ec_point_copy (tmpa, ad->gamma2[ad->i][j]); + ec_point_copy (tmpb, ad->delta2[ad->i][j]); + + /* apply random masking to first summand */ + smc_zkp_2dle (ad->gamma2[ad->i][j], + ad->delta2[ad->i][j], + tmpa, + tmpb, + NULL, + proof2); + + ec_point_serialize (gamma, ad->gamma2[ad->i][j]); + ec_point_serialize (delta, ad->delta2[ad->i][j]); + + /* add winner determination for own gamma,delta */ + gcry_mpi_ec_add (ad->gamma2[ad->i][j], + ad->gamma2[ad->i][j], + ad->tmpa1[j], + ec_ctx); + gcry_mpi_ec_add (ad->delta2[ad->i][j], + ad->delta2[ad->i][j], + ad->tmpb1[j], + ec_ctx); + + cur += sizeof (*gamma) + sizeof (*delta) + sizeof (*proof2); + } + + gcry_mpi_point_release (tmpa); + gcry_mpi_point_release (tmpb); + return ret; } int fp_pub_recv_outcome (struct BRANDT_Auction *ad, const unsigned char *buf, - size_t buflen, - uint16_t sender) + size_t buflen, + uint16_t sender) { - int ret = 0; - const unsigned char *cur = buf; - struct proof_2dle *proof2; - gcry_mpi_point_t gamma = gcry_mpi_point_new (0); - gcry_mpi_point_t delta = gcry_mpi_point_new (0); - - brandt_assert (ad && buf); - - if (buflen != (ad->k * (2 * sizeof (struct ec_mpi) + sizeof (*proof2)))) - { - GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, - "libbrandt", - "wrong size of received outcome\n"); - goto quit; - } - - for (uint16_t j = 0; j < ad->k; j++) - { - ec_point_parse (gamma, (struct ec_mpi *)cur); - ec_point_parse (delta, &((struct ec_mpi *)cur)[1]); - proof2 = (struct proof_2dle *)(cur + 2 * sizeof (struct ec_mpi)); - if (smc_zkp_2dle_check (gamma, - delta, - ad->gamma2[sender][j], - ad->delta2[sender][j], - proof2)) - { - GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, - "libbrandt", - "wrong zkp2 for gamma, delta received\n"); - goto quit; - } - ec_point_copy (ad->gamma2[sender][j], gamma); - ec_point_copy (ad->delta2[sender][j], delta); - - /* add winner determination summand */ - gcry_mpi_ec_add (ad->gamma2[sender][j], - ad->gamma2[sender][j], - ad->tmpa1[j], - ec_ctx); - gcry_mpi_ec_add (ad->delta2[sender][j], - ad->delta2[sender][j], - ad->tmpb1[j], - ec_ctx); - - cur += 2 * sizeof (struct ec_mpi) + sizeof (*proof2); - } - - ret = 1; + int ret = 0; + const unsigned char *cur = buf; + struct proof_2dle *proof2; + gcry_mpi_point_t gamma = gcry_mpi_point_new (0); + gcry_mpi_point_t delta = gcry_mpi_point_new (0); + + brandt_assert (ad && buf); + + if (buflen != (ad->k * (2 * sizeof (struct ec_mpi) + sizeof (*proof2)))) + { + GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, + "libbrandt", + "wrong size of received outcome\n"); + goto quit; + } + + for (uint16_t j = 0; j < ad->k; j++) + { + ec_point_parse (gamma, (struct ec_mpi *) cur); + ec_point_parse (delta, &((struct ec_mpi *) cur)[1]); + proof2 = (struct proof_2dle *) (cur + 2 * sizeof (struct ec_mpi)); + if (smc_zkp_2dle_check (gamma, + delta, + ad->gamma2[sender][j], + ad->delta2[sender][j], + proof2)) + { + GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, + "libbrandt", + "wrong zkp2 for gamma, delta received\n"); + goto quit; + } + ec_point_copy (ad->gamma2[sender][j], gamma); + ec_point_copy (ad->delta2[sender][j], delta); + + /* add winner determination summand */ + gcry_mpi_ec_add (ad->gamma2[sender][j], + ad->gamma2[sender][j], + ad->tmpa1[j], + ec_ctx); + gcry_mpi_ec_add (ad->delta2[sender][j], + ad->delta2[sender][j], + ad->tmpb1[j], + ec_ctx); + + cur += 2 * sizeof (struct ec_mpi) + sizeof (*proof2); + } + + ret = 1; quit: - gcry_mpi_point_release (gamma); - gcry_mpi_point_release (delta); - return ret; + gcry_mpi_point_release (gamma); + gcry_mpi_point_release (delta); + return ret; } void fp_pub_prep_decryption (struct BRANDT_Auction *ad) { - gcry_mpi_point_t tmp = gcry_mpi_point_new (0); + gcry_mpi_point_t tmp = gcry_mpi_point_new (0); - ad->phi2 = smc_init2 (ad->n, ad->k); - brandt_assert (ad->phi2); + ad->phi2 = smc_init2 (ad->n, ad->k); + brandt_assert (ad->phi2); - for (uint16_t j = 0; j < ad->k; j++) - { - smc_sum (tmp, &ad->delta2[0][j], ad->n, ad->k); + for (uint16_t j = 0; j < ad->k; j++) + { + smc_sum (tmp, &ad->delta2[0][j], ad->n, ad->k); - /* copy still encrypted outcome to all other bidder layers so they - * don't have to be recomputed to check the ZK proof_2dle's from - * other bidders when receiving their outcome decryption messages */ - for (uint16_t a = 0; a < ad->n; a++) - ec_point_copy (ad->phi2[a][j], tmp); - } + /* copy still encrypted outcome to all other bidder layers so they + * don't have to be recomputed to check the ZK proof_2dle's from + * other bidders when receiving their outcome decryption messages */ + for (uint16_t a = 0; a < ad->n; a++) + ec_point_copy (ad->phi2[a][j], tmp); + } - gcry_mpi_point_release (tmp); + gcry_mpi_point_release (tmp); } @@ -297,92 +297,92 @@ fp_pub_prep_decryption (struct BRANDT_Auction *ad) unsigned char * fp_pub_decrypt_outcome (struct BRANDT_Auction *ad, size_t *buflen) { - unsigned char *ret; - unsigned char *cur; - gcry_mpi_point_t tmp = gcry_mpi_point_new (0); - struct msg_head *head; - struct ec_mpi *phi; - struct proof_2dle *proof2; + unsigned char *ret; + unsigned char *cur; + gcry_mpi_point_t tmp = gcry_mpi_point_new (0); + struct msg_head *head; + struct ec_mpi *phi; + struct proof_2dle *proof2; - brandt_assert (ad && buflen); + brandt_assert (ad && buflen); - *buflen = (sizeof (*head) + ad->k * (sizeof (*phi) + sizeof (*proof2))); - ret = GNUNET_new_array (*buflen, unsigned char); + *buflen = (sizeof (*head) + ad->k * (sizeof (*phi) + sizeof (*proof2))); + ret = GNUNET_new_array (*buflen, unsigned char); - head = (struct msg_head *)ret; - head->prot_version = htonl (0); - head->msg_type = htonl (msg_decrypt); - cur = ret + sizeof (*head); + head = (struct msg_head *) ret; + head->prot_version = htonl (0); + head->msg_type = htonl (msg_decrypt); + cur = ret + sizeof (*head); - for (uint16_t j = 0; j < ad->k; j++) - { - phi = (struct ec_mpi *)cur; - proof2 = (struct proof_2dle *)(cur + sizeof (*phi)); + for (uint16_t j = 0; j < ad->k; j++) + { + phi = (struct ec_mpi *) cur; + proof2 = (struct proof_2dle *) (cur + sizeof (*phi)); - ec_point_copy (tmp, ad->phi2[ad->i][j]); + ec_point_copy (tmp, ad->phi2[ad->i][j]); - /* decrypt outcome component and prove the correct key was used */ - smc_zkp_2dle (ad->phi2[ad->i][j], - NULL, - tmp, - ec_gen, - ad->x, - proof2); + /* decrypt outcome component and prove the correct key was used */ + smc_zkp_2dle (ad->phi2[ad->i][j], + NULL, + tmp, + ec_gen, + ad->x, + proof2); - ec_point_serialize (phi, ad->phi2[ad->i][j]); + ec_point_serialize (phi, ad->phi2[ad->i][j]); - cur += sizeof (*phi) + sizeof (*proof2); - } + cur += sizeof (*phi) + sizeof (*proof2); + } - gcry_mpi_point_release (tmp); - return ret; + gcry_mpi_point_release (tmp); + return ret; } int fp_pub_recv_decryption (struct BRANDT_Auction *ad, const unsigned char *buf, - size_t buflen, - uint16_t sender) + size_t buflen, + uint16_t sender) { - int ret = 0; - const unsigned char *cur = buf; - struct proof_2dle *proof2; - gcry_mpi_point_t phi = gcry_mpi_point_new (0); - - brandt_assert (ad && buf); - - if (buflen != (ad->k * (sizeof (struct ec_mpi) + sizeof (*proof2)))) - { - GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, - "libbrandt", - "wrong size of received outcome decryption\n"); - goto quit; - } - - for (uint16_t j = 0; j < ad->k; j++) - { - ec_point_parse (phi, (struct ec_mpi *)cur); - proof2 = (struct proof_2dle *)(cur + sizeof (struct ec_mpi)); - if (smc_zkp_2dle_check (phi, - ad->y[sender], - ad->phi2[sender][j], - ec_gen, - proof2)) - { - GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, - "libbrandt", - "wrong zkp2 for phi, y received\n"); - goto quit; - } - ec_point_copy (ad->phi2[sender][j], phi); - cur += sizeof (struct ec_mpi) + sizeof (*proof2); - } - - ret = 1; + int ret = 0; + const unsigned char *cur = buf; + struct proof_2dle *proof2; + gcry_mpi_point_t phi = gcry_mpi_point_new (0); + + brandt_assert (ad && buf); + + if (buflen != (ad->k * (sizeof (struct ec_mpi) + sizeof (*proof2)))) + { + GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, + "libbrandt", + "wrong size of received outcome decryption\n"); + goto quit; + } + + for (uint16_t j = 0; j < ad->k; j++) + { + ec_point_parse (phi, (struct ec_mpi *) cur); + proof2 = (struct proof_2dle *) (cur + sizeof (struct ec_mpi)); + if (smc_zkp_2dle_check (phi, + ad->y[sender], + ad->phi2[sender][j], + ec_gen, + proof2)) + { + GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, + "libbrandt", + "wrong zkp2 for phi, y received\n"); + goto quit; + } + ec_point_copy (ad->phi2[sender][j], phi); + cur += sizeof (struct ec_mpi) + sizeof (*proof2); + } + + ret = 1; quit: - gcry_mpi_point_release (phi); - return ret; + gcry_mpi_point_release (phi); + return ret; } @@ -390,57 +390,71 @@ struct BRANDT_Result * fp_pub_determine_outcome (struct BRANDT_Auction *ad, uint16_t *len) { - struct BRANDT_Result *ret; - int32_t price = -1; - int32_t winner = -1; - int dlogi = -1; - gcry_mpi_point_t sum_gamma = gcry_mpi_point_new (0); - gcry_mpi_point_t sum_phi = gcry_mpi_point_new (0); - - brandt_assert (ad); - - for (uint16_t j = ad->k - 1; j >= 0; j--) - { - smc_sum (sum_gamma, &ad->gamma2[0][j], ad->n, ad->k); - smc_sum (sum_phi, &ad->phi2[0][j], ad->n, ad->k); - gcry_mpi_ec_sub (sum_gamma, sum_gamma, sum_phi, ec_ctx); - /* first non-zero component determines the price */ - if (ec_point_cmp (sum_gamma, ec_zero)) - { - price = j; - break; - } - } - - dlogi = GNUNET_CRYPTO_ecc_dlog (ad->dlogctx, sum_gamma); - brandt_assert (dlogi > 0); - - /* all bidders participated with a multiplicative share */ - dlogi /= ad->n; - - /* can only support up to bits(dlogi) bidders */ - brandt_assert (sizeof (int) * 8 > ad->n); - for (uint16_t i = 0; i < ad->n; i++) - { - /* first set bit determines the winner */ - if (dlogi & (1 << i)) - { - winner = i; - break; - } - } - - gcry_mpi_point_release (sum_gamma); - gcry_mpi_point_release (sum_phi); - - if (-1 == winner || -1 == price) - return NULL; - - ret = GNUNET_new (struct BRANDT_Result); - ret->bidder = winner; - ret->price = price; - ret->status = BRANDT_bidder_won; - if (len) - *len = 1; - return ret; + struct BRANDT_Result *ret; + int32_t price = -1; + int32_t winner = -1; + int dlogi = -1; + gcry_mpi_point_t sum_gamma = gcry_mpi_point_new (0); + gcry_mpi_point_t sum_phi = gcry_mpi_point_new (0); + + brandt_assert (ad); + + for (uint16_t j = ad->k - 1; j >= 0; j--) + { + smc_sum (sum_gamma, &ad->gamma2[0][j], ad->n, ad->k); + smc_sum (sum_phi, &ad->phi2[0][j], ad->n, ad->k); + gcry_mpi_ec_sub (sum_gamma, sum_gamma, sum_phi, ec_ctx); + /* first non-zero component determines the price */ + if (ec_point_cmp (sum_gamma, ec_zero)) + { + price = j; + break; + } + } + + { + struct GNUNET_CRYPTO_EccPoint ec_point = {0}; + gcry_mpi_t q_y; + + GNUNET_assert (0 == gcry_mpi_ec_set_point ("q", sum_gamma, ec_ctx)); + q_y = gcry_mpi_ec_get_mpi ("q@eddsa", ec_ctx, 0); + GNUNET_assert (q_y); + GNUNET_CRYPTO_mpi_print_unsigned (ec_point.v, + sizeof(ec_point.v), + q_y); + dlogi = GNUNET_CRYPTO_ecc_dlog (ad->dlogctx, + &ec_point); + gcry_mpi_release (q_y); + } + + brandt_assert (dlogi > 0); + + /* all bidders participated with a multiplicative share */ + dlogi /= ad->n; + + /* can only support up to bits(dlogi) bidders */ + brandt_assert (sizeof (int) * 8 > ad->n); + for (uint16_t i = 0; i < ad->n; i++) + { + /* first set bit determines the winner */ + if (dlogi & (1 << i)) + { + winner = i; + break; + } + } + + gcry_mpi_point_release (sum_gamma); + gcry_mpi_point_release (sum_phi); + + if (-1 == winner || -1 == price) + return NULL; + + ret = GNUNET_new (struct BRANDT_Result); + ret->bidder = winner; + ret->price = price; + ret->status = BRANDT_bidder_won; + if (len) + *len = 1; + return ret; } |