split different auction format algorithms into separate files

1 files changed, 438 insertions, 0 deletions

diff --git a/fp_pub.c b/fp_pub.c
new file mode 100644
index 0000000..eb0cfe1
--- /dev/null
+++ b/fp_pub.c
@@ -0,0 +1,438 @@
+/* This file is part of libbrandt.
+ * Copyright (C) 2016 GNUnet e.V.
+ *
+ * libbrandt is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later
+ * version.
+ *
+ * libbrandt 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * libbrandt.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * @file fp_pub.c
+ * @brief Implementation of the first price public outcome algorithm.
+ * @author Markus Teich
+ */
+
+#include "platform.h"
+
+#include <gcrypt.h>
+
+#include "crypto.h"
+#include "internals.h"
+#include "util.h"
+
+
+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);
+}
+
+
+/**
+ * fp_pub_compute_outcome computes the outcome for first price auctions with a
+ * public outcome and packs it into a message buffer together with proofs of
+ * correctnes.
+ *
+ * @param[in] ad Pointer to the BRANDT_Auction struct to operate on
+ * @param[out] buflen Size of the returned message buffer in bytes
+ * @return A buffer containing the encrypted outcome vectors
+ * which needs to be broadcast
+ */
+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 for losing bidders */
+		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)
+{
+	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))))
+	{
+		weprintf ("wrong size of received outcome");
+		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))
+		{
+			weprintf ("wrong zkp2 for gamma, delta received");
+			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;
+}
+
+
+void
+fp_pub_prep_decryption (struct BRANDT_Auction *ad)
+{
+	gcry_mpi_point_t tmp = gcry_mpi_point_new (0);
+
+	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);
+
+		/* 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);
+}
+
+
+/**
+ * fp_pub_decrypt_outcome decrypts part of the outcome and packs it into a
+ * message buffer together with proofs of correctnes.
+ *
+ * @param[in] ad Pointer to the BRANDT_Auction struct to operate on
+ * @param[out] buflen Size of the returned message buffer in bytes
+ * @return A buffer containing the own share of the decrypted outcome
+ * which needs to be broadcast
+ */
+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;
+
+	brandt_assert (ad && buflen);
+
+	*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);
+
+	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]);
+
+		/* 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]);
+
+		cur += sizeof (*phi) + sizeof (*proof2);
+	}
+
+	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)
+{
+	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))))
+	{
+		weprintf ("wrong size of received outcome decryption");
+		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))
+		{
+			weprintf ("wrong zkp2 for phi, y received");
+			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;
+}
+
+
+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 (ec_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 - 1 >= 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;
+}