Add AEAD parameters and key types to C++ library.

PiperOrigin-RevId: 531532517

4 files changed, 130 insertions, 11 deletions

diff --git a/cc/aead/BUILD.bazel b/cc/aead/BUILD.bazel
index db654c4e3..7d2813453 100644
--- a/cc/aead/BUILD.bazel
+++ b/cc/aead/BUILD.bazel
@@ -330,6 +330,23 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "aead_key",
+    hdrs = ["aead_key.h"],
+    include_prefix = "tink/aead",
+    deps = [
+        ":aead_parameters",
+        "//:key",
+    ],
+)
+
+cc_library(
+    name = "aead_parameters",
+    hdrs = ["aead_parameters.h"],
+    include_prefix = "tink/aead",
+    deps = ["//:parameters"],
+)
+
 # tests
 
 cc_test(
diff --git a/cc/aead/CMakeLists.txt b/cc/aead/CMakeLists.txt
index 485cd557f..ce0816181 100644
--- a/cc/aead/CMakeLists.txt
+++ b/cc/aead/CMakeLists.txt
@@ -308,6 +308,34 @@ tink_cc_library(
   TESTONLY
 )
 
+tink_cc_library(
+  NAME failing_aead
+  SRCS
+    failing_aead.cc
+    failing_aead.h
+  DEPS
+    absl::strings
+    tink::core::aead
+  TESTONLY
+)
+
+tink_cc_library(
+  NAME aead_key
+  SRCS
+    aead_key.h
+  DEPS
+    tink::aead::aead_parameters
+    tink::core::key
+)
+
+tink_cc_library(
+  NAME aead_parameters
+  SRCS
+    aead_parameters.h
+  DEPS
+    tink::core::parameters
+)
+
 # tests
 
 tink_cc_test(
@@ -616,17 +644,6 @@ tink_cc_test(
     tink::proto::tink_cc_proto
 )
 
-tink_cc_library(
-  NAME failing_aead
-  SRCS
-    failing_aead.cc
-    failing_aead.h
-  DEPS
-    absl::strings
-    tink::core::aead
-  TESTONLY
-)
-
 tink_cc_test(
   NAME failing_aead_test
   SRCS
diff --git a/cc/aead/aead_key.h b/cc/aead/aead_key.h
new file mode 100644
index 000000000..64f7880b3
--- /dev/null
+++ b/cc/aead/aead_key.h
@@ -0,0 +1,53 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef TINK_AEAD_AEAD_KEY_H_
+#define TINK_AEAD_AEAD_KEY_H_
+
+#include <string>
+
+#include "tink/aead/aead_parameters.h"
+#include "tink/key.h"
+
+namespace crypto {
+namespace tink {
+
+// Represents a function to encrypt and decrypt data using authenticated
+// encryption with associated data (AEAD).
+class AeadKey : public Key {
+ public:
+  // Returns the bytes prefixed to every ciphertext generated by this key.
+  //
+  // In order to make key rotation more efficient, Tink allows every AEAD key to
+  // have an associated ciphertext output prefix. When decrypting a ciphertext,
+  // only keys with a matching prefix have to be tried.
+  //
+  // Note that a priori, the output prefix may not be unique in a keyset
+  // (i.e., different keys in a keyset may have the same prefix or one prefix
+  // may be a prefix of another). To avoid this, built-in Tink keys use the
+  // convention that the prefix is either '0x00<big endian key id>' or
+  // '0x01<big endian key id>'.
+  virtual std::string GetOutputPrefix() const = 0;
+
+  const AeadParameters& GetParameters() const override = 0;
+
+  bool operator==(const Key& other) const override = 0;
+};
+
+}  // namespace tink
+}  // namespace crypto
+
+#endif  // TINK_AEAD_AEAD_KEY_H_
diff --git a/cc/aead/aead_parameters.h b/cc/aead/aead_parameters.h
new file mode 100644
index 000000000..dc5caadbf
--- /dev/null
+++ b/cc/aead/aead_parameters.h
@@ -0,0 +1,32 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef TINK_AEAD_AEAD_PARAMETERS_H_
+#define TINK_AEAD_AEAD_PARAMETERS_H_
+
+#include "tink/parameters.h"
+
+namespace crypto {
+namespace tink {
+
+// Describes an `AeadKey` (e.g., key attributes), excluding the randomly chosen
+// key material.
+class AeadParameters : public Parameters {};
+
+}  // namespace tink
+}  // namespace crypto
+
+#endif  // TINK_AEAD_AEAD_PARAMETERS_H_