1 files changed, 128 insertions, 0 deletions
diff --git a/dom/webauthn/WebAuthnCBORUtil.cpp b/dom/webauthn/WebAuthnCBORUtil.cpp
new file mode 100644
index 0000000000..51255e80d8
--- /dev/null
+++ b/dom/webauthn/WebAuthnCBORUtil.cpp
@@ -0,0 +1,128 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "cbor-cpp/src/cbor.h"
+#include "mozilla/dom/WebAuthnCBORUtil.h"
+#include "mozilla/dom/WebAuthnUtil.h"
+
+namespace mozilla::dom {
+
+nsresult CBOREncodePublicKeyObj(const CryptoBuffer& aPubKeyBuf,
+                                /* out */ CryptoBuffer& aPubKeyObj) {
+  mozilla::dom::CryptoBuffer xBuf, yBuf;
+  nsresult rv = U2FDecomposeECKey(aPubKeyBuf, xBuf, yBuf);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // COSE_Key object. See https://tools.ietf.org/html/rfc8152#section-7
+  cbor::output_dynamic cborPubKeyOut;
+  cbor::encoder encoder(cborPubKeyOut);
+  encoder.write_map(5);
+  {
+    encoder.write_int(1);   // kty
+    encoder.write_int(2);   // EC2
+    encoder.write_int(3);   // alg
+    encoder.write_int(-7);  // ES256
+
+    // See https://tools.ietf.org/html/rfc8152#section-13.1
+    encoder.write_int(-1);  // crv
+    encoder.write_int(1);   // P-256
+    encoder.write_int(-2);  // x
+    encoder.write_bytes(xBuf.Elements(), xBuf.Length());
+    encoder.write_int(-3);  // y
+    encoder.write_bytes(yBuf.Elements(), yBuf.Length());
+  }
+
+  if (!aPubKeyObj.Assign(cborPubKeyOut.data(), cborPubKeyOut.size())) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  return NS_OK;
+}
+
+nsresult CBOREncodeFidoU2FAttestationObj(
+    const CryptoBuffer& aAuthDataBuf, const CryptoBuffer& aAttestationCertBuf,
+    const CryptoBuffer& aSignatureBuf,
+    /* out */ CryptoBuffer& aAttestationObj) {
+  /*
+  Attestation Object, encoded in CBOR (description is CDDL)
+
+  attObj = {
+              authData: bytes,
+              $$attStmtType
+           }
+  $$attStmtType //= (
+                        fmt: "fido-u2f",
+                        attStmt: u2fStmtFormat
+                    )
+  u2fStmtFormat = {
+                      x5c: [ attestnCert: bytes, * (caCert: bytes) ],
+                      sig: bytes
+                  }
+  */
+  cbor::output_dynamic cborAttOut;
+  cbor::encoder encoder(cborAttOut);
+  encoder.write_map(3);
+  {
+    encoder.write_string("fmt");
+    encoder.write_string("fido-u2f");
+
+    encoder.write_string("attStmt");
+    encoder.write_map(2);
+    {
+      encoder.write_string("sig");
+      encoder.write_bytes(aSignatureBuf.Elements(), aSignatureBuf.Length());
+
+      encoder.write_string("x5c");
+      // U2F wire protocol can only deliver 1 certificate, so it's never a chain
+      encoder.write_array(1);
+      encoder.write_bytes(aAttestationCertBuf.Elements(),
+                          aAttestationCertBuf.Length());
+    }
+
+    encoder.write_string("authData");
+    encoder.write_bytes(aAuthDataBuf.Elements(), aAuthDataBuf.Length());
+  }
+
+  if (!aAttestationObj.Assign(cborAttOut.data(), cborAttOut.size())) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  return NS_OK;
+}
+
+nsresult CBOREncodeNoneAttestationObj(const CryptoBuffer& aAuthDataBuf,
+                                      /* out */ CryptoBuffer& aAttestationObj) {
+  /*
+  Attestation Object, encoded in CBOR (description is CDDL)
+
+  $$attStmtType //= (
+                          fmt: "none",
+                          attStmt: emptyMap
+                      )
+
+  emptyMap = {}
+  */
+  cbor::output_dynamic cborAttOut;
+  cbor::encoder encoder(cborAttOut);
+  encoder.write_map(3);
+  {
+    encoder.write_string("fmt");
+    encoder.write_string("none");
+
+    encoder.write_string("attStmt");
+    encoder.write_map(0);
+
+    encoder.write_string("authData");
+    encoder.write_bytes(aAuthDataBuf.Elements(), aAuthDataBuf.Length());
+  }
+
+  if (!aAttestationObj.Assign(cborAttOut.data(), cborAttOut.size())) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  return NS_OK;
+}
+
+}  // namespace mozilla::dom