Home • Explore • Blog • CI
☰



postgresql
5th chunk of `doc/src/sgml/pgcrypto.sgml`
75296dbaad54abacc8651947d440391bd88cd7ff0a5b96ab0000000100000fa0
 years</entry>
       <entry>3927 years</entry>
       <entry>100k</entry>
      </row>
      <row>
       <entry><literal>crypt-bf/7</literal></entry>
       <entry>3648</entry>
       <entry>2 years</entry>
       <entry>1929 years</entry>
       <entry>50k</entry>
      </row>
      <row>
       <entry><literal>crypt-bf/6</literal></entry>
       <entry>7168</entry>
       <entry>1 year</entry>
       <entry>982 years</entry>
       <entry>25k</entry>
      </row>
      <row>
       <entry><literal>crypt-bf/5</literal></entry>
       <entry>13504</entry>
       <entry>188 days</entry>
       <entry>521 years</entry>
       <entry>12.5k</entry>
      </row>
      <row>
       <entry><literal>crypt-md5</literal></entry>
       <entry>171584</entry>
       <entry>15 days</entry>
       <entry>41 years</entry>
       <entry>1k</entry>
      </row>
      <row>
       <entry><literal>crypt-des</literal></entry>
       <entry>23221568</entry>
       <entry>157.5 minutes</entry>
       <entry>108 days</entry>
       <entry>7</entry>
      </row>
      <row>
       <entry><literal>sha1</literal></entry>
       <entry>37774272</entry>
       <entry>90 minutes</entry>
       <entry>68 days</entry>
       <entry>4</entry>
      </row>
      <row>
       <entry><literal>md5</literal> (hash)</entry>
       <entry>150085504</entry>
       <entry>22.5 minutes</entry>
       <entry>17 days</entry>
       <entry>1</entry>
      </row>
     </tbody>
    </tgroup>
   </table>

   <para>
    Notes:
   </para>

   <itemizedlist>
    <listitem>
     <para>
     The machine used is an Intel Mobile Core i3.
     </para>
    </listitem>
    <listitem>
     <para>
      <literal>crypt-des</literal> and <literal>crypt-md5</literal> algorithm numbers are
      taken from John the Ripper v1.6.38 <literal>-test</literal> output.
     </para>
    </listitem>
    <listitem>
     <para>
      <literal>md5 hash</literal> numbers are from mdcrack 1.2.
     </para>
    </listitem>
    <listitem>
     <para>
      <literal>sha1</literal> numbers are from lcrack-20031130-beta.
     </para>
    </listitem>
    <listitem>
     <para>
      <literal>crypt-bf</literal> numbers are taken using a simple program that
      loops over 1000 8-character passwords.  That way the speed
      with different numbers of iterations can be shown.  For reference: <literal>john
      -test</literal> shows 13506 loops/sec for <literal>crypt-bf/5</literal>.
      (The very small
      difference in results is in accordance with the fact that the
      <literal>crypt-bf</literal> implementation in <filename>pgcrypto</filename>
      is the same one used in John the Ripper.)
     </para>
    </listitem>
   </itemizedlist>

   <para>
    Note that <quote>try all combinations</quote> is not a realistic exercise.
    Usually password cracking is done with the help of dictionaries, which
    contain both regular words and various mutations of them.  So, even
    somewhat word-like passwords could be cracked much faster than the above
    numbers suggest, while a 6-character non-word-like password may escape
    cracking.  Or not.
   </para>
  </sect3>
 </sect2>

 <sect2 id="pgcrypto-pgp-enc-funcs">
  <title>PGP Encryption Functions</title>

  <para>
   The functions here implement the encryption part of the OpenPGP
   (<ulink url="https://datatracker.ietf.org/doc/html/rfc4880">RFC 4880</ulink>)
   standard.  Supported are both symmetric-key and public-key encryption.
  </para>

  <para>
   An encrypted PGP message consists of 2 parts, or <firstterm>packets</firstterm>:
  </para>
  <itemizedlist>
   <listitem>
    <para>
     Packet containing a session key &mdash; either symmetric-key or public-key
     encrypted.
    </para>
   </listitem>
   <listitem>
    <para>
     Packet containing data encrypted with the session key.
    </para>
   </listitem>
  </itemizedlist>

  <para>
   When encrypting with a symmetric key (i.e., a password):
  </para>
  <orderedlist>
   <listitem>
    <para>
Title: Password Hashing and PGP Encryption
Summary
The document discusses password hashing algorithms, including their iteration counts and speeds, and provides tables to compare their relative slowness, and then introduces PGP encryption functions, which implement the OpenPGP standard for symmetric-key and public-key encryption, explaining the structure of an encrypted PGP message and the process of encrypting with a symmetric key.