1 files changed, 352 insertions, 0 deletions
diff --git a/src/util/merchant_signatures.c b/src/util/merchant_signatures.c
new file mode 100644
index 000000000..35e0b0e07
--- /dev/null
+++ b/src/util/merchant_signatures.c
@@ -0,0 +1,352 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2020 Taler Systems SA
+
+  TALER 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, or (at your option) any later version.
+
+  TALER 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
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file merchant_signatures.c
+ * @brief Utility functions for Taler merchant signatures
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler_util.h"
+#include "taler_signatures.h"
+
+
+GNUNET_NETWORK_STRUCT_BEGIN
+
+/**
+ * @brief Format used to generate the signature on a request to obtain
+ * the wire transfer identifier associated with a deposit.
+ */
+struct TALER_DepositTrackPS
+{
+  /**
+   * Purpose must be #TALER_SIGNATURE_MERCHANT_TRACK_TRANSACTION.
+   */
+  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+  /**
+   * Hash over the proposal data of the contract for which this deposit is made.
+   */
+  struct TALER_PrivateContractHashP h_contract_terms GNUNET_PACKED;
+
+  /**
+   * Hash over the wiring information of the merchant.
+   */
+  struct TALER_MerchantWireHashP h_wire GNUNET_PACKED;
+
+  /**
+   * The coin's public key.  This is the value that must have been
+   * signed (blindly) by the Exchange.
+   */
+  struct TALER_CoinSpendPublicKeyP coin_pub;
+
+};
+
+GNUNET_NETWORK_STRUCT_END
+
+
+void
+TALER_merchant_deposit_sign (
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  const struct TALER_MerchantWireHashP *h_wire,
+  const struct TALER_CoinSpendPublicKeyP *coin_pub,
+  const struct TALER_MerchantPrivateKeyP *merchant_priv,
+  struct TALER_MerchantSignatureP *merchant_sig)
+{
+  struct TALER_DepositTrackPS dtp = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_TRACK_TRANSACTION),
+    .purpose.size = htonl (sizeof (dtp)),
+    .h_contract_terms = *h_contract_terms,
+    .h_wire = *h_wire,
+    .coin_pub = *coin_pub
+  };
+
+  GNUNET_CRYPTO_eddsa_sign (&merchant_priv->eddsa_priv,
+                            &dtp,
+                            &merchant_sig->eddsa_sig);
+}
+
+
+enum GNUNET_GenericReturnValue
+TALER_merchant_deposit_verify (
+  const struct TALER_MerchantPublicKeyP *merchant,
+  const struct TALER_CoinSpendPublicKeyP *coin_pub,
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  const struct TALER_MerchantWireHashP *h_wire,
+  const struct TALER_MerchantSignatureP *merchant_sig)
+{
+  struct TALER_DepositTrackPS tps = {
+    .purpose.size = htonl (sizeof (tps)),
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_TRACK_TRANSACTION),
+    .coin_pub = *coin_pub,
+    .h_contract_terms = *h_contract_terms,
+    .h_wire = *h_wire
+  };
+
+  return
+    GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MERCHANT_TRACK_TRANSACTION,
+                                &tps,
+                                &merchant_sig->eddsa_sig,
+                                &merchant->eddsa_pub);
+}
+
+
+/**
+ * @brief Format used to generate the signature on a request to refund
+ * a coin into the account of the customer.
+ */
+struct TALER_RefundRequestPS
+{
+  /**
+   * Purpose must be #TALER_SIGNATURE_MERCHANT_REFUND.
+   */
+  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+  /**
+   * Hash over the proposal data to identify the contract
+   * which is being refunded.
+   */
+  struct TALER_PrivateContractHashP h_contract_terms GNUNET_PACKED;
+
+  /**
+   * The coin's public key.  This is the value that must have been
+   * signed (blindly) by the Exchange.
+   */
+  struct TALER_CoinSpendPublicKeyP coin_pub;
+
+  /**
+   * Merchant-generated transaction ID for the refund.
+   */
+  uint64_t rtransaction_id GNUNET_PACKED;
+
+  /**
+   * Amount to be refunded, including refund fee charged by the
+   * exchange to the customer.
+   */
+  struct TALER_AmountNBO refund_amount;
+};
+
+
+void
+TALER_merchant_refund_sign (
+  const struct TALER_CoinSpendPublicKeyP *coin_pub,
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  uint64_t rtransaction_id,
+  const struct TALER_Amount *amount,
+  const struct TALER_MerchantPrivateKeyP *merchant_priv,
+  struct TALER_MerchantSignatureP *merchant_sig)
+{
+  struct TALER_RefundRequestPS rr = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_REFUND),
+    .purpose.size = htonl (sizeof (rr)),
+    .h_contract_terms = *h_contract_terms,
+    .coin_pub = *coin_pub,
+    .rtransaction_id = GNUNET_htonll (rtransaction_id)
+  };
+
+  TALER_amount_hton (&rr.refund_amount,
+                     amount);
+  GNUNET_CRYPTO_eddsa_sign (&merchant_priv->eddsa_priv,
+                            &rr,
+                            &merchant_sig->eddsa_sig);
+}
+
+
+enum GNUNET_GenericReturnValue
+TALER_merchant_refund_verify (
+  const struct TALER_CoinSpendPublicKeyP *coin_pub,
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  uint64_t rtransaction_id,
+  const struct TALER_Amount *amount,
+  const struct TALER_MerchantPublicKeyP *merchant_pub,
+  const struct TALER_MerchantSignatureP *merchant_sig)
+{
+  struct TALER_RefundRequestPS rr = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_REFUND),
+    .purpose.size = htonl (sizeof (rr)),
+    .h_contract_terms = *h_contract_terms,
+    .coin_pub = *coin_pub,
+    .rtransaction_id = GNUNET_htonll (rtransaction_id)
+  };
+
+  TALER_amount_hton (&rr.refund_amount,
+                     amount);
+  return
+    GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MERCHANT_REFUND,
+                                &rr,
+                                &merchant_sig->eddsa_sig,
+                                &merchant_pub->eddsa_pub);
+}
+
+
+/**
+ * @brief Information signed by the exchange's master
+ * key affirming the IBAN details for the exchange.
+ */
+struct TALER_MerchantWireDetailsPS
+{
+
+  /**
+   * Purpose is #TALER_SIGNATURE_MERCHANT_WIRE_DETAILS.
+   */
+  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+  /**
+   * Salted hash over the account holder's payto:// URL and
+   * the salt, as done by #TALER_merchant_wire_signature_hash().
+   */
+  struct TALER_MerchantWireHashP h_wire_details GNUNET_PACKED;
+
+};
+
+
+enum GNUNET_GenericReturnValue
+TALER_merchant_wire_signature_check (
+  const char *payto_uri,
+  const struct TALER_WireSaltP *salt,
+  const struct TALER_MerchantPublicKeyP *merch_pub,
+  const struct TALER_MerchantSignatureP *merch_sig)
+{
+  struct TALER_MerchantWireDetailsPS wd = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_WIRE_DETAILS),
+    .purpose.size = htonl (sizeof (wd))
+  };
+
+  TALER_merchant_wire_signature_hash (payto_uri,
+                                      salt,
+                                      &wd.h_wire_details);
+  return GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MERCHANT_WIRE_DETAILS,
+                                     &wd,
+                                     &merch_sig->eddsa_sig,
+                                     &merch_pub->eddsa_pub);
+}
+
+
+void
+TALER_merchant_wire_signature_make (
+  const char *payto_uri,
+  const struct TALER_WireSaltP *salt,
+  const struct TALER_MerchantPrivateKeyP *merch_priv,
+  struct TALER_MerchantSignatureP *merch_sig)
+{
+  struct TALER_MerchantWireDetailsPS wd = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_WIRE_DETAILS),
+    .purpose.size = htonl (sizeof (wd))
+  };
+
+  TALER_merchant_wire_signature_hash (payto_uri,
+                                      salt,
+                                      &wd.h_wire_details);
+  GNUNET_CRYPTO_eddsa_sign (&merch_priv->eddsa_priv,
+                            &wd,
+                            &merch_sig->eddsa_sig);
+}
+
+
+/**
+ * Used by merchants to return signed responses to /pay requests.
+ * Currently only used to return 200 OK signed responses.
+ */
+struct TALER_PaymentResponsePS
+{
+  /**
+   * Set to #TALER_SIGNATURE_MERCHANT_PAYMENT_OK. Note that
+   * unsuccessful payments are usually proven by some exchange's signature.
+   */
+  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+  /**
+   * Hash of the proposal data associated with this confirmation
+   */
+  struct TALER_PrivateContractHashP h_contract_terms;
+};
+
+void
+TALER_merchant_pay_sign (
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  const struct TALER_MerchantPrivateKeyP *merch_priv,
+  struct TALER_MerchantSignatureP *merch_sig)
+{
+  struct TALER_PaymentResponsePS mr = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_PAYMENT_OK),
+    .purpose.size = htonl (sizeof (mr)),
+    .h_contract_terms = *h_contract_terms
+  };
+
+  GNUNET_CRYPTO_eddsa_sign (&merch_priv->eddsa_priv,
+                            &mr,
+                            &merch_sig->eddsa_sig);
+}
+
+
+enum GNUNET_GenericReturnValue
+TALER_merchant_pay_verify (
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  const struct TALER_MerchantPublicKeyP *merchant_pub,
+  const struct TALER_MerchantSignatureP *merchant_sig)
+{
+  struct TALER_PaymentResponsePS pr = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_PAYMENT_OK),
+    .purpose.size = htonl (sizeof (pr)),
+    .h_contract_terms = *h_contract_terms
+  };
+
+  return
+    GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MERCHANT_PAYMENT_OK,
+                                &pr,
+                                &merchant_sig->eddsa_sig,
+                                &merchant_pub->eddsa_pub);
+}
+
+
+/**
+ * The contract sent by the merchant to the wallet.
+ */
+struct TALER_ProposalDataPS
+{
+  /**
+   * Purpose header for the signature over the proposal data
+   * with purpose #TALER_SIGNATURE_MERCHANT_CONTRACT.
+   */
+  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+  /**
+   * Hash of the JSON contract in UTF-8 including 0-termination,
+   * using JSON_COMPACT | JSON_SORT_KEYS
+   */
+  struct TALER_PrivateContractHashP hash;
+};
+
+void
+TALER_merchant_contract_sign (
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  const struct TALER_MerchantPrivateKeyP *merch_priv,
+  struct GNUNET_CRYPTO_EddsaSignature *merch_sig)
+{
+  struct TALER_ProposalDataPS pdps = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_CONTRACT),
+    .purpose.size = htonl (sizeof (pdps)),
+    .hash = *h_contract_terms
+  };
+
+  GNUNET_CRYPTO_eddsa_sign (&merch_priv->eddsa_priv,
+                            &pdps,
+                            merch_sig);
+}
+
+
+// NB: "TALER_merchant_contract_verify" not (yet?) needed / not defined.
+
+/* end of merchant_signatures.c */