diff --git a/symmetric_key.cpp b/symmetric_key.cpp
new file mode 100644
index 0000000..5105c7d
--- /dev/null
+++ b/symmetric_key.cpp
@@ -0,0 +1,111 @@
+/*
+ * Copyright 2014 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "symmetric_key.h"
+
+#include <assert.h>
+
+#include <openssl/err.h>
+#include <openssl/rand.h>
+
+#include "aes_key.h"
+#include "unencrypted_key_blob.h"
+
+namespace keymaster {
+
+/* static */
+SymmetricKey* SymmetricKey::GenerateKey(keymaster_algorithm_t algorithm,
+                                        const AuthorizationSet& key_description,
+                                        const Logger& logger, keymaster_error_t* error) {
+    if (!error)
+        return NULL;
+
+    *error = KM_ERROR_OK;
+
+    UniquePtr<SymmetricKey> key;
+    switch (algorithm) {
+    case KM_ALGORITHM_AES:
+        key.reset(new AesKey(key_description, logger));
+        break;
+    default:
+        *error = KM_ERROR_UNSUPPORTED_ALGORITHM;
+        return NULL;
+    };
+
+    uint32_t key_size_bits;
+    if (!key_description.GetTagValue(TAG_KEY_SIZE, &key_size_bits) || key_size_bits % 8 != 0) {
+        *error = KM_ERROR_UNSUPPORTED_KEY_SIZE;
+        return NULL;
+    }
+
+    key->key_data_size_ = key_size_bits / 8;
+    if (key->key_data_size_ > MAX_KEY_SIZE) {
+        *error = KM_ERROR_UNSUPPORTED_KEY_SIZE;
+        return NULL;
+    }
+    if (!RAND_bytes(key->key_data_, key->key_data_size_)) {
+        logger.error("Error %ul generating %d bit AES key", ERR_get_error(), key_size_bits);
+        *error = KM_ERROR_UNKNOWN_ERROR;
+        return NULL;
+    }
+
+    if (*error != KM_ERROR_OK)
+        return NULL;
+    return key.release();
+}
+
+/* static */
+SymmetricKey* SymmetricKey::CreateKey(keymaster_algorithm_t algorithm,
+                                      const UnencryptedKeyBlob& blob, const Logger& logger,
+                                      keymaster_error_t* error) {
+    switch (algorithm) {
+    case KM_ALGORITHM_AES:
+        return new AesKey(blob, logger, error);
+    default:
+        *error = KM_ERROR_UNSUPPORTED_ALGORITHM;
+        return NULL;
+    }
+}
+
+SymmetricKey::SymmetricKey(const UnencryptedKeyBlob& blob, const Logger& logger,
+                           keymaster_error_t* error)
+    : Key(blob, logger), key_data_size_(blob.unencrypted_key_material_length()) {
+    if (error)
+        *error = LoadKey(blob);
+}
+
+SymmetricKey::~SymmetricKey() {
+    memset_s(key_data_, 0, MAX_KEY_SIZE);
+}
+
+keymaster_error_t SymmetricKey::LoadKey(const UnencryptedKeyBlob& blob) {
+    assert(blob.unencrypted_key_material_length() == key_data_size_);
+    memcpy(key_data_, blob.unencrypted_key_material(), key_data_size_);
+
+    return KM_ERROR_OK;
+}
+
+keymaster_error_t SymmetricKey::key_material(UniquePtr<uint8_t[]>* key_material,
+                                             size_t* size) const {
+    *size = key_data_size_;
+    key_material->reset(new uint8_t[*size]);
+    if (!key_material->get())
+        return KM_ERROR_MEMORY_ALLOCATION_FAILED;
+    memcpy(key_material->get(), key_data_, *size);
+    return KM_ERROR_OK;
+}
+
+}  // namespace keymaster