From 509657bfef59221a6a113c49330ee06ed66c9da9 Mon Sep 17 00:00:00 2001
From: Thien-Thi Nguyen <ttn@gnuvola.org>
Date: Sun, 17 Apr 2022 19:53:17 -0400
Subject: [PATCH] Add abstraction: TALER_merchant_contract_sign
MIME-Version: 1.0
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Additionally, this change removes ‘struct TALER_ProposalDataPS’
from the public API.

* src/include/taler_crypto_lib.h
  (TALER_merchant_contract_sign): New func decl.

* src/include/taler_signatures.h
  (struct TALER_ProposalDataPS): Delete.

* src/util/merchant_signatures.c
  (struct TALER_ProposalDataPS): Move here from taler_signatures.h.
  (TALER_merchant_contract_sign): New func.
---
 src/include/taler_crypto_lib.h | 14 +++++++++++++
 src/include/taler_signatures.h | 19 -----------------
 src/util/merchant_signatures.c | 38 ++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 19 deletions(-)

diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index 6be9db9a4..554cb1a26 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -4601,6 +4601,20 @@ TALER_merchant_pay_verify (
   const struct TALER_MerchantSignatureP *merchant_sig);
 
 
+/**
+ * Sign contract sent by the merchant to the wallet.
+ *
+ * @param h_contract_terms hash of the contract terms
+ * @param merch_priv private key to sign with
+ * @param[out] merch_sig where to write the signature
+ */
+void
+TALER_merchant_contract_sign (
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  const struct TALER_MerchantPrivateKeyP *merch_priv,
+  struct GNUNET_CRYPTO_EddsaSignature *merch_sig);
+
+
 /* **************** /management/extensions offline signing **************** */
 
 /**
diff --git a/src/include/taler_signatures.h b/src/include/taler_signatures.h
index 249c01b68..0137ff65e 100644
--- a/src/include/taler_signatures.h
+++ b/src/include/taler_signatures.h
@@ -422,25 +422,6 @@ struct TALER_DepositTrackPS
 };
 
 
-/**
- * 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;
-};
-
-
 GNUNET_NETWORK_STRUCT_END
 
 #endif
diff --git a/src/util/merchant_signatures.c b/src/util/merchant_signatures.c
index 0a7489f71..84daca2c4 100644
--- a/src/util/merchant_signatures.c
+++ b/src/util/merchant_signatures.c
@@ -229,4 +229,42 @@ TALER_merchant_pay_verify (
                                 &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 */