--- /dev/null
+
+\chapter{Data Encryption}
+\label{DataEncryption}
+\index[general]{Data Encryption}
+\index[general]{Encryption!Data}
+\index[general]{Data Encryption}
+
+Bacula permits file data encryption and signing within the File Daemon (or
+Client) prior to sending data to the Storage Daemon. Upon restoration,
+file signatures are validated and any mismatches are reported. At no time
+does the Director or the Storage Daemon have access to unencrypted file
+contents.
+
+
+It is very important to specify what this implementation does NOT
+do:
+\begin{itemize}
+\item There is one important restore problem to be aware of, namely, it's
+ possible for the director to restore new keys or a Bacula configuration
+ file to the client, and thus force later backups to be made with a
+ compromised key and/or with no encryption at all. You can avoid this by
+ not changing the location of the keys in your Bacula File daemon
+ configuration file, and not changing your File daemon keys. If you do
+ change either one, you must ensure that no restore is done that restores
+ the old configuration or the old keys. In general, the worst effect of
+ this will be that you can no longer connect the File daemon.
+
+\item The implementation does not encrypt file metadata such as file path
+ names, permissions, and ownership. Extended attributes are also currently
+ not encrypted. However, Mac OS X resource forks are encrypted.
+\end{itemize}
+
+Encryption and signing are implemented using RSA private keys coupled with
+self-signed x509 public certificates. This is also sometimes known as PKI
+or Public Key Infrastructure.
+
+Each File Daemon should be given its own unique private/public key pair.
+In addition to this key pair, any number of "Master Keys" may be specified
+-- these are key pairs that may be used to decrypt any backups should the
+File Daemon key be lost. Only the Master Key's public certificate should
+be made available to the File Daemon. Under no circumstances should the
+Master Private Key be shared or stored on the Client machine.
+
+The Master Keys should be backed up to a secure location, such as a CD
+placed in a in a fire-proof safe or bank safety deposit box. The Master
+Keys should never be kept on the same machine as the Storage Daemon or
+Director if you are worried about an unauthorized party compromising either
+machine and accessing your encrypted backups.
+
+While less critical than the Master Keys, File Daemon Keys are also a prime
+candidate for off-site backups; burn the key pair to a CD and send the CD
+home with the owner of the machine.
+
+NOTE!!! If you lose your encryption keys, backups will be unrecoverable.
+{\bf ALWAYS} store a copy of your master keys in a secure, off-site location.
+
+The basic algorithm used for each backup session (Job) is:
+\begin{enumerate}
+\item The File daemon generates a session key.
+\item The FD encrypts that session key via PKE for all recipients (the file
+daemon, any master keys).
+\item The FD uses that session key to perform symmetric encryption on the data.
+\end{enumerate}
+
+
+\section{Building Bacula with Encryption Support}
+\index[general]{Building Bacula with Encryption Support}
+
+The configuration option for enabling OpenSSL encryption support has not changed
+since Bacula 1.38. To build Bacula with encryption support, you will need
+the OpenSSL libraries and headers installed. When configuring Bacula, use:
+
+\begin{verbatim}
+ ./configure --with-openssl ...
+\end{verbatim}
+
+\section{Encryption Technical Details}
+\index[general]{Encryption Technical Details}
+
+The implementation uses 128bit AES-CBC, with RSA encrypted symmetric
+session keys. The RSA key is user supplied.
+If you are running OpenSSL 0.9.8 or later, the signed file hash uses
+SHA-256 -- otherwise, SHA-1 is used.
+
+End-user configuration settings for the algorithms are not currently
+exposed -- only the algorithms listed above are used. However, the
+data written to Volume supports arbitrary symmetric, asymmetric, and
+digest algorithms for future extensibility, and the back-end
+implementation currently supports:
+
+\begin{verbatim}
+Symmetric Encryption:
+ - 128, 192, and 256-bit AES-CBC
+ - Blowfish-CBC
+
+Asymmetric Encryption (used to encrypt symmetric session keys):
+ - RSA
+
+Digest Algorithms:
+ - MD5
+ - SHA1
+ - SHA256
+ - SHA512
+\end{verbatim}
+
+The various algorithms are exposed via an entirely re-usable,
+OpenSSL-agnostic API (ie, it is possible to drop in a new encryption
+backend). The Volume format is DER-encoded ASN.1, modeled after the
+Cryptographic Message Syntax from RFC 3852. Unfortunately, using CMS
+directly was not possible, as at the time of coding a free software
+streaming DER decoder/encoder was not available.
+
+
+\section{Decrypting with a Master Key}
+\index[general]{Decrypting with a Master Key}
+
+It is preferable to retain a secure, non-encrypted copy of the
+client's own encryption keypair. However, should you lose the
+client's keypair, recovery with the master keypair is possible.
+
+You must:
+\begin{itemize}
+\item Concatenate the master private and public key into a single
+ keypair file, ie:
+ cat master.key master.cert \gt master.keypair
+
+\item Set the PKI Keypair statement in your bacula configuration file:
+
+\begin{verbatim}
+ PKI Keypair = master.keypair
+\end{verbatim}
+
+\item Start the restore. The master keypair will be used to decrypt
+ the file data.
+
+\end{itemize}
+
+
+\section{Generating Private/Public Encryption Keys}
+\index[general]{Generating Private/Public Encryption Keypairs}
+
+Generate a Master Key Pair with:
+
+\footnotesize
+\begin{verbatim}
+ openssl genrsa -out master.key 2048
+ openssl req -new -key master.key -x509 -out master.cert
+\end{verbatim}
+\normalsize
+
+Generate a File Daemon Key Pair for each FD:
+
+\footnotesize
+\begin{verbatim}
+ openssl genrsa -out fd-example.key 2048
+ openssl req -new -key fd-example.key -x509 -out fd-example.cert
+ cat fd-example.key fd-example.cert >fd-example.pem
+\end{verbatim}
+\normalsize
+
+Note, there seems to be a lot of confusion around the file extensions given
+to these keys. For example, a .pem file can contain all the following:
+private keys (RSA and DSA), public keys (RSA and DSA) and (x509) certificates.
+It is the default format for OpenSSL. It stores data Base64 encoded DER format,
+surrounded by ASCII headers, so is suitable for text mode transfers between
+systems. A .pem file may contain any number of keys either public or
+private. We use it in cases where there is both a public and a private
+key.
+
+Typically, above we have used the .cert extension to refer to X509
+certificate encoding that contains only a single public key.
+
+
+\section{Example Data Encryption Configuration}
+\index[general]{Example!File Daemon Configuration File}
+\index[general]{Example!Data Encryption Configuration File}
+\index[general]{Example Data Encryption Configuration}
+
+{\bf bacula-fd.conf}
+\footnotesize
+\begin{verbatim}
+FileDaemon {
+ Name = example-fd
+ FDport = 9102 # where we listen for the director
+ WorkingDirectory = /var/bacula/working
+ Pid Directory = /var/run
+ Maximum Concurrent Jobs = 20
+
+ PKI Signatures = Yes # Enable Data Signing
+ PKI Encryption = Yes # Enable Data Encryption
+ PKI Keypair = "/etc/bacula/fd-example.pem" # Public and Private Keys
+ PKI Master Key = "/etc/bacula/master.cert" # ONLY the Public Key
+}
+\end{verbatim}
+\normalsize
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