mirror of
https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
241 lines
11 KiB
HTML
241 lines
11 KiB
HTML
<?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 18.1.40</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. The Berkeley DB Environment </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
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Rijndael/AES (also known as the Advanced Encryption Standard
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and Federal Information Processing Standard (FIPS) 197)
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algorithm for encryption or decryption. The algorithm is
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configured to use a 128-bit key. Berkeley DB uses a 16-byte
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initialization vector generated using the Mersenne Twister.
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All encrypted information is additionally checksummed using
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the SHA1 Secure Hash Algorithm, using a 160-bit message
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digest.
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</p>
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<p>
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The encryption support provided with Berkeley DB is
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intended to protect applications from an attacker obtaining
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physical access to the media on which a Berkeley DB database
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is stored, or an attacker compromising a system on which
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Berkeley DB is running but who is unable to read system or
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process memory on that system. <span class="bold"><strong> The
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encryption support provided with Berkeley DB will not
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protect applications from attackers able to read system
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memory 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
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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
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create in the environment are encrypted/decrypted by the
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password you specify 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
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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
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re-creating them. Finally, encrypted databases cannot be read
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on systems with a different endianness than the system that
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created the encrypted database.
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</p>
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<p>
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When a database is encrypted, its log files are also encrypted, so
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accessing the logs also requires the encryption key. By default,
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logs are placed in the same directory as the environment.
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Encrypted log files should never be simply deleted. For
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instructions on how to properly remove log files see,
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<a class="xref" href="transapp_logfile.html" title="Log file removal">Log file removal</a>.
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</p>
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<p>
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Each encrypted database environment (including all its
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encrypted databases) is encrypted using a single password and
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a single algorithm. Applications wanting to provide a finer
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granularity of database access must either use multiple
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database environments or implement additional access controls
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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 <a class="xref" href="env_region.html" title="Shared memory regions">Shared memory regions</a>
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supporting the database environment are not encrypted. For
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this reason, it may be possible for an attacker to read some
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or all of an encrypted database by reading the on-disk files
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that back these shared memory regions. To prevent such
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attacks, applications may want to use in-memory filesystem
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support (on systems that support it), or the <a href="../api_reference/C/envopen.html#envopen_DB_PRIVATE" class="olink">DB_PRIVATE</a> or
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<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 place the
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shared memory regions in memory that is never written to a
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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
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on the machine as well. Finally, when backing database
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environment shared regions with the filesystem, Berkeley DB
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can be configured to overwrite the shared regions before
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removing them by specifying the <a href="../api_reference/C/envset_flags.html#set_flags_DB_OVERWRITE" class="olink">DB_OVERWRITE</a> flag. This
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option is only effective in the presence of fixed-block
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filesystems, journaling or logging filesystems will require
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operating system support and probably modification of the
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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
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and log files in an encrypted environment are maintained in an
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unencrypted state. Specifically, log record headers are not
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encrypted, only the actual log records. Additionally, database
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internal page header fields are not encrypted. These page
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header fields includes information such as the page's <a href="../api_reference/C/lsn.html" class="olink">DB_LSN</a>
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number and position in the database's sort order.
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</p>
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<p>
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Log records and database pages distributed by a replication
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master to replicated clients are transmitted to the clients in
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unencrypted form. If encryption is desired in a replicated
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application, the use of a secure transport is strongly
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suggested and all sites in the replication group must use
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encryption.
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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
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for writing 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
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checksum 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
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the Mersenne 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,
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SHA1 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 12c 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
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have IPP installed along with the cryptography extension. The
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IPP performance is higher in most cases compared to the
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current AES implementation. See <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="https://software.intel.com/en-us/articles/intel-integrated-performance-primitives-documentation/" target="_top">
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Intel Documentation</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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