1 files changed, 27 insertions, 0 deletions
diff --git a/third_party/rust/cose/src/util.rs b/third_party/rust/cose/src/util.rs
new file mode 100644
index 0000000000..8f1cf7e954
--- /dev/null
+++ b/third_party/rust/cose/src/util.rs
@@ -0,0 +1,27 @@
+use cbor::CborType;
+
+/// Sig_structure is a CBOR array:
+///
+/// Sig_structure = [
+///   context : "Signature" / "Signature1" / "CounterSignature",
+///   body_protected : empty_or_serialized_map,
+///   ? sign_protected : empty_or_serialized_map,
+///   external_aad : bstr,
+///   payload : bstr
+/// ]
+///
+/// In this case, the context is "Signature". There is no external_aad, so this defaults to a
+/// zero-length bstr.
+pub fn get_sig_struct_bytes(
+    protected_body_header_serialized: CborType,
+    protected_signature_header_serialized: CborType,
+    payload: &[u8],
+) -> Vec<u8> {
+    let sig_structure_array: Vec<CborType> = vec![CborType::String(String::from("Signature")),
+                                                  protected_body_header_serialized,
+                                                  protected_signature_header_serialized,
+                                                  CborType::Null,
+                                                  CborType::Bytes(payload.to_vec())];
+
+    CborType::Array(sig_structure_array).serialize()
+}