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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>19.8. Encryption Options</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="preventing-server-spoofing.html" title="19.7. Preventing Server Spoofing" /><link rel="next" href="ssl-tcp.html" title="19.9. Secure TCP/IP Connections with SSL" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">19.8. Encryption Options</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="preventing-server-spoofing.html" title="19.7. Preventing Server Spoofing">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="runtime.html" title="Chapter 19. Server Setup and Operation">Up</a></td><th width="60%" align="center">Chapter 19. Server Setup and Operation</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="ssl-tcp.html" title="19.9. Secure TCP/IP Connections with SSL">Next</a></td></tr></table><hr /></div><div class="sect1" id="ENCRYPTION-OPTIONS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">19.8. Encryption Options</h2></div></div></div><a id="id-1.6.6.11.2" class="indexterm"></a><p>
   <span class="productname">PostgreSQL</span> offers encryption at several
   levels, and provides flexibility in protecting data from disclosure
   due to database server theft, unscrupulous administrators, and
   insecure networks. Encryption might also be required to secure
   sensitive data such as medical records or financial transactions.
  </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">Password Encryption</span></dt><dd><p>
     Database user passwords are stored as hashes (determined by the setting
     <a class="xref" href="runtime-config-connection.html#GUC-PASSWORD-ENCRYPTION">password_encryption</a>), so the administrator cannot
     determine the actual password assigned to the user. If SCRAM or MD5
     encryption is used for client authentication, the unencrypted password is
     never even temporarily present on the server because the client encrypts
     it before being sent across the network. SCRAM is preferred, because it
     is an Internet standard and is more secure than the PostgreSQL-specific
     MD5 authentication protocol.
    </p></dd><dt><span class="term">Encryption For Specific Columns</span></dt><dd><p>
     The <a class="xref" href="pgcrypto.html" title="F.28. pgcrypto">pgcrypto</a> module allows certain fields to be
     stored encrypted.
     This is useful if only some of the data is sensitive.
     The client supplies the decryption key and the data is decrypted
     on the server and then sent to the client.
    </p><p>
     The decrypted data and the decryption key are present on the
     server for a brief time while it is being decrypted and
     communicated between the client and server. This presents a brief
     moment where the data and keys can be intercepted by someone with
     complete access to the database server, such as the system
     administrator.
    </p></dd><dt><span class="term">Data Partition Encryption</span></dt><dd><p>
     Storage encryption can be performed at the file system level or the
     block level.  Linux file system encryption options include eCryptfs
     and EncFS, while FreeBSD uses PEFS.  Block level or full disk
     encryption options include dm-crypt + LUKS on Linux and GEOM
     modules geli and gbde on FreeBSD.  Many other operating systems
     support this functionality, including Windows.
    </p><p>
     This mechanism prevents unencrypted data from being read from the
     drives if the drives or the entire computer is stolen. This does
     not protect against attacks while the file system is mounted,
     because when mounted, the operating system provides an unencrypted
     view of the data. However, to mount the file system, you need some
     way for the encryption key to be passed to the operating system,
     and sometimes the key is stored somewhere on the host that mounts
     the disk.
    </p></dd><dt><span class="term">Encrypting Data Across A Network</span></dt><dd><p>
      SSL connections encrypt all data sent across the network: the
      password, the queries, and the data returned. The
      <code class="filename">pg_hba.conf</code> file allows administrators to specify
      which hosts can use non-encrypted connections (<code class="literal">host</code>)
      and which require SSL-encrypted connections
      (<code class="literal">hostssl</code>). Also, clients can specify that they
      connect to servers only via SSL.
     </p><p>
      GSSAPI-encrypted connections encrypt all data sent across the network,
      including queries and data returned.  (No password is sent across the
      network.)  The <code class="filename">pg_hba.conf</code> file allows
      administrators to specify which hosts can use non-encrypted connections
      (<code class="literal">host</code>) and which require GSSAPI-encrypted connections
      (<code class="literal">hostgssenc</code>).  Also, clients can specify that they
      connect to servers only on GSSAPI-encrypted connections
      (<code class="literal">gssencmode=require</code>).
     </p><p>
      <span class="application">Stunnel</span> or
      <span class="application">SSH</span> can also be used to encrypt
      transmissions.
     </p></dd><dt><span class="term">SSL Host Authentication</span></dt><dd><p>
     It is possible for both the client and server to provide SSL
     certificates to each other. It takes some extra configuration
     on each side, but this provides stronger verification of identity
     than the mere use of passwords. It prevents a computer from
     pretending to be the server just long enough to read the password
     sent by the client. It also helps prevent <span class="quote"><span class="quote">man in the middle</span></span>
     attacks where a computer between the client and server pretends to
     be the server and reads and passes all data between the client and
     server.
    </p></dd><dt><span class="term">Client-Side Encryption</span></dt><dd><p>
     If the system administrator for the server's machine cannot be trusted,
     it is necessary
     for the client to encrypt the data; this way, unencrypted data
     never appears on the database server. Data is encrypted on the
     client before being sent to the server, and database results have
     to be decrypted on the client before being used.
    </p></dd></dl></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="preventing-server-spoofing.html" title="19.7. Preventing Server Spoofing">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="runtime.html" title="Chapter 19. Server Setup and Operation">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ssl-tcp.html" title="19.9. Secure TCP/IP Connections with SSL">Next</a></td></tr><tr><td width="40%" align="left" valign="top">19.7. Preventing Server Spoofing </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 19.9. Secure TCP/IP Connections with SSL</td></tr></table></div></body></html>