depends: Add cxx crate to dependencies

Cargo.lock

@@ -463,6 +463,35 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "cxx"
+version = "1.0.68"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7e599641dff337570f6aa9c304ecca92341d30bf72e1c50287869ed6a36615a6"
+dependencies = [
+ "cc",
+ "cxxbridge-flags",
+ "cxxbridge-macro",
+ "link-cplusplus",
+]
+
+[[package]]
+name = "cxxbridge-flags"
+version = "1.0.68"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3894ad0c6d517cb5a4ce8ec20b37cd0ea31b480fe582a104c5db67ae21270853"
+
+[[package]]
+name = "cxxbridge-macro"
+version = "1.0.68"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34fa7e395dc1c001083c7eed28c8f0f0b5a225610f3b6284675f444af6fab86b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "dashmap"
 version = "4.0.2"
@@ -968,6 +997,7 @@ dependencies = [
  "bls12_381",
  "byteorder",
  "clearscreen",
+ "cxx",
  "ed25519-zebra",
  "group",
  "gumdrop",
@@ -1001,6 +1031,15 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "link-cplusplus"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8cae2cd7ba2f3f63938b9c724475dfb7b9861b545a90324476324ed21dbc8c8"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "lock_api"
 version = "0.4.7"

Cargo.toml

@@ -57,6 +57,9 @@ zcash_proofs = "0.6"
 ed25519-zebra = "3"
 zeroize = "1.4.2"
 
+# Rust/C++ interop
+cxx = { version = "1.0", features = ["c++17"] }
+
 # Rust threading
 rayon = "1.5"