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HTML
229 lines
10 KiB
HTML
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Encryption</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="up" href="env.html" title="Chapter 9. The Berkeley DB Environment" />
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<link rel="prev" href="env_security.html" title="Security" />
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<link rel="next" href="env_remote.html" title="Remote filesystems" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.2</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Encryption</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="env_security.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 9.
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The Berkeley DB Environment
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="env_remote.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="env_encrypt"></a>Encryption</h2>
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</div>
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</div>
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</div>
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<p>
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Berkeley DB optionally supports encryption using the Rijndael/AES
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(also known as the Advanced Encryption Standard and Federal
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Information Processing Standard (FIPS) 197) algorithm for
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encryption or decryption. The algorithm is configured to use a
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128-bit key. Berkeley DB uses a 16-byte initialization vector
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generated using the Mersenne Twister. All encrypted information is
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additionally checksummed using the SHA1 Secure Hash Algorithm,
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using a 160-bit message digest.
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</p>
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<p>
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The encryption support provided with Berkeley DB is intended to
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protect applications from an attacker obtaining physical access to
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the media on which a Berkeley DB database is stored, or an attacker
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compromising a system on which Berkeley DB is running but who is
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unable to read system or process memory on that system.
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<span class="bold"><strong>
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The encryption support provided with Berkeley DB will not
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protect applications from attackers able to read system memory
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on the system where Berkeley DB is running.
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</strong></span>
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</p>
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<p>
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To encrypt a database, you must configure the database for
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encryption prior to creating it. If you are using a database
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environment, you must also configure the environment for
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encryption. In order to create an encrypted database within an
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environment, you:
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</p>
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<div class="orderedlist">
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<ol type="1">
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<li>
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<p>
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Configure the environment for encryption using the
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<a href="../api_reference/C/envset_encrypt.html" class="olink">DB_ENV->set_encrypt()</a> method.
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</p>
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</li>
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<li>
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<p>
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Open the database environment.
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</p>
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</li>
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<li>
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<p>
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Specify the <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_ENCRYPT" class="olink">DB_ENCRYPT</a> flag to the database handle.
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</p>
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</li>
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<li>
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<p>
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Open the database.
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</p>
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</li>
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</ol>
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</div>
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<p>
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Once you have done that, all of the databases that you create in
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the environment are encrypted/decrypted by the password you specify
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using the <a href="../api_reference/C/envset_encrypt.html" class="olink">DB_ENV->set_encrypt()</a> method.
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</p>
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<p>
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For databases not created in an environment:
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</p>
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<div class="orderedlist">
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<ol type="1">
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<li>
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<p>
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Specify the <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_ENCRYPT" class="olink">DB_ENCRYPT</a> flag to the database handle.
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</p>
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</li>
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<li>
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<p>
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Call the <a href="../api_reference/C/dbset_encrypt.html" class="olink">DB->set_encrypt()</a> method.
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</p>
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</li>
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<li>
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<p>
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Open the database.
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</p>
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</li>
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</ol>
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</div>
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<p>
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Note that databases cannot be converted to an encrypted
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format after they have been created without dumping and re-creating
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them. Finally, encrypted databases cannot be read on systems with
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a different endianness than the system that created the encrypted
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database.
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</p>
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<p>
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Each encrypted database environment (including all its encrypted
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databases) is encrypted using a single password and a single
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algorithm. Applications wanting to provide a finer granularity of
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database access must either use multiple database environments or
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implement additional access controls outside of Berkeley DB.
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</p>
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<p>
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The only encrypted parts of a database environment are its
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databases and its log files. Specifically, the
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<a class="xref" href="env_region.html" title="Shared memory regions">Shared memory regions</a> supporting
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the database environment are not encrypted. For this reason, it
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may be possible for an attacker to read some or all of an encrypted
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database by reading the on-disk files that back these shared memory
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regions. To prevent such attacks, applications may want to use
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in-memory filesystem support (on systems that support it), or the
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<a href="../api_reference/C/envopen.html#envopen_DB_PRIVATE" class="olink">DB_PRIVATE</a> or <a href="../api_reference/C/envopen.html#envopen_DB_SYSTEM_MEM" class="olink">DB_SYSTEM_MEM</a> flags to the <a href="../api_reference/C/envopen.html" class="olink">DB_ENV->open()</a> method, to
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place the shared memory regions in memory that is never written to
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a disk. As some systems page system memory to a backing disk, it
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is important to consider the specific operating system running on
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the machine as well. Finally, when backing database environment
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shared regions with the filesystem, Berkeley DB can be configured
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to overwrite the shared regions before removing them by specifying
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the <a href="../api_reference/C/envset_flags.html#set_flags_DB_OVERWRITE" class="olink">DB_OVERWRITE</a> flag. This option is only effective in the
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presence of fixed-block filesystems, journaling or logging
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filesystems will require operating system support and probably
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modification of the Berkeley DB sources.
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</p>
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<p>
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While all user data is encrypted, parts of the databases and log
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files in an encrypted environment are maintained in an unencrypted
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state. Specifically, log record headers are not encrypted, only
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the actual log records. Additionally, database internal page
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header fields are not encrypted. These page header fields includes
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information such as the page's <a href="../api_reference/C/lsn.html" class="olink">DB_LSN</a> number and position in the
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database's sort order.
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</p>
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<p>
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Log records distributed by a replication master to replicated
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clients are transmitted to the clients in unencrypted form. If
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encryption is desired in a replicated application, the use of a
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secure transport is strongly suggested.
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</p>
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<p>
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We gratefully acknowledge:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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Vincent Rijmen, Antoon Bosselaers and Paulo Barreto for writing
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the Rijndael/AES code used in Berkeley DB.
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</li>
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<li>
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Steve Reid and James H. Brown for writing the SHA1 checksum
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code used in Berkeley DB.
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</li>
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<li>
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Makoto Matsumoto and Takuji Nishimura for writing the Mersenne
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Twister code used in Berkeley DB.
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</li>
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<li>
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Adam Stubblefield for integrating the Rijndael/AES, SHA1
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checksum and Mersenne Twister code into Berkeley DB.
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</li>
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</ul>
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</div>
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<p>
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Berkeley DB 11g Release 2 supports encryption using Intel's
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Performance Primitive (IPP) on Linux. This works only on Intel
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processors. To use Berkeley DB with IPP encryption, you must have
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IPP installed along with the cryptography extension. The IPP
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performance is higher in most cases compared to the current AES
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implementation. See
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<a href="../installation/build_unix_conf.html#build_unix_conf.--with-cryptography" class="olink">--with-cryptography</a>
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for more information. See the
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<a class="ulink" href="http://software.intel.com/en-us/articles/intel-integrated-performance-primitives-documentation/" target="_top">
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Intel Documenation</a> for more information on IPP.
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</p>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="env_security.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="env.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="env_remote.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Security </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Remote filesystems</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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