Add RSA signing support.

Change-Id: Icdcbd978d58c8764618b995571d1e8b649959ef0
diff --git a/google_keymaster_utils.cpp b/google_keymaster_utils.cpp
new file mode 100644
index 0000000..bd44cfd
--- /dev/null
+++ b/google_keymaster_utils.cpp
@@ -0,0 +1,74 @@
+/*
+ * 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 "google_keymaster_utils.h"
+
+namespace keymaster {
+
+Buffer::~Buffer() {
+    delete[] buffer_;
+}
+
+bool Buffer::Reinitialize(size_t size) {
+    delete[] buffer_;
+
+    buffer_ = new uint8_t[size];
+    if (buffer_ == NULL)
+        return false;
+    buffer_size_ = size;
+    read_position_ = 0;
+    write_position_ = 0;
+    return true;
+}
+
+bool Buffer::Reinitialize(const void* data, size_t data_len) {
+    delete[] buffer_;
+
+    buffer_ = new uint8_t[data_len];
+    if (buffer_ == NULL)
+        return false;
+    buffer_size_ = data_len;
+    memcpy(buffer_, data, data_len);
+    read_position_ = 0;
+    write_position_ = buffer_size_;
+    return true;
+}
+
+size_t Buffer::available_write() const {
+    return buffer_size_ - write_position_;
+}
+
+size_t Buffer::available_read() const {
+    return write_position_ - read_position_;
+}
+
+bool Buffer::write(const uint8_t* src, size_t write_length) {
+    if (available_write() < write_length)
+        return false;
+    memcpy(buffer_ + write_position_, src, write_length);
+    write_position_ += write_length;
+    return true;
+}
+
+bool Buffer::read(uint8_t* dest, size_t read_length) {
+    if (available_read() < read_length)
+        return false;
+    memcpy(dest, buffer_ + read_position_, read_length);
+    read_position_ += read_length;
+    return true;
+}
+
+}  // namespace keymaster