school_archives/OSU Coursework/CS 444 - Operating Systems II/Kernel Assignments/Project 3/design.tex

\section{Design}
The framework for the device driver was taken from the "simple block device" from the website: http://blog.superpat.com/2010/05/04/a-simple-block-driver-for-linux-kernel-2-6-31/. The following changes were then needed to add crypto functionality:
\begin{itemize}
\item Addition of cipher
\item Addition of cipher key
\item Addition of module parameter for the key
\item Change the read and write functionality so that the encryption and decryption occurs as the reads and writes happen
\end{itemize}

The following psuedocode describes how the read and write functionality with encryption and decryption was implemented:
\begin{lstlisting}[lineskip=3pt,keywords={if,else,while}]
if (write) {
	for(iterate through desired length) {
		encrypt using crypto_cipher_encrypt_one()
	}	
}
else {
	for(iterate through desired length) {
		decrypt using crypto_cipher_decrypt_one()
	}	
}		
\end{lstlisting}