Library for the AES-CBC en/decryption of 4K blocks

The 'aes_cbc_4k' library is simple wrapper around libsparkcrypto to
serve as a backend for storage encryption. It operates on data chunks of
4 KiB and uses AES-CBC while incorporating the block number and the
private key as salt values.

repos/gems/include/aes_cbc_4k/aes_cbc_4k.h

@@ -0,0 +1,31 @@
+/*
+ * \brief  Interface for AES CBC encryption/decrytion of 4KiB data blocks
+ * \author Norman Feske
+ * \date   2018-12-20
+ */
+
+/*
+ * Copyright (C) 2018 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _AES_CBC_4K_H_
+#define _AES_CBC_4K_H_
+
+namespace Aes_cbc_4k {
+
+	struct Key   { char values[32];   };
+	struct Block { char values[4096]; };
+
+	struct Plaintext  : Block { };
+	struct Ciphertext : Block { };
+
+	struct Block_number { Genode::uint64_t value; };
+
+	void encrypt(Key const &, Block_number, Plaintext  const &, Ciphertext &);
+	void decrypt(Key const &, Block_number, Ciphertext const &, Plaintext  &);
+}
+
+#endif /* _AES_CBC_4K_H_ */