Build protobufs for compact formats

zcash_client_backend/proto/compact_formats.proto

@@ -0,0 +1,47 @@
+syntax = "proto3";
+package cash.z.wallet.sdk.rpc;
+option go_package = "walletrpc";
+
+// Remember that proto3 fields are all optional. A field that is not present will be set to its zero value.
+// bytes fields of hashes are in canonical little-endian format.
+
+// CompactBlock is a packaging of ONLY the data from a block that's needed to:
+//   1. Detect a payment to your shielded Sapling address
+//   2. Detect a spend of your shielded Sapling notes
+//   3. Update your witnesses to generate new Sapling spend proofs.
+message CompactBlock {
+    uint32 protoVersion = 1; // the version of this wire format, for storage
+    uint64 height = 2; // the height of this block
+    bytes hash = 3;
+    uint32 time = 4;
+    bytes header = 5; // (hash and time) OR (full header)
+    repeated CompactTx vtx = 6; // compact transactions from this block
+}
+
+message CompactTx {
+    // Index and hash will allow the receiver to call out to chain
+    // explorers or other data structures to retrieve more information
+    // about this transaction.
+    uint64 index = 1;
+    bytes hash = 2;
+
+    // The transaction fee: present if server can provide. In the case of a
+    // stateless server and a transaction with transparent inputs, this will be
+    // unset because the calculation requires reference to prior transactions.
+    // in a pure-Sapling context, the fee will be calculable as:
+    //    valueBalance + (sum(vPubNew) - sum(vPubOld) - sum(tOut))
+    uint32 fee = 3;
+
+    repeated CompactSpend spends = 4;
+    repeated CompactOutput outputs = 5;
+}
+
+message CompactSpend {
+    bytes nf = 1;
+}
+
+message CompactOutput {
+    bytes cmu = 1;
+    bytes epk = 2;
+    bytes ciphertext = 3;
+}