179 lines
3.4 KiB
HTML
179 lines
3.4 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Ada</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Secure Programming for Linux and Unix HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Language-Specific Issues"
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HREF="language-specific.html"><LINK
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REL="PREVIOUS"
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TITLE="Shell Scripting Languages (sh and csh Derivatives)"
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HREF="shell.html"><LINK
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REL="NEXT"
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TITLE="Java"
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HREF="java.html"></HEAD
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><BODY
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Secure Programming for Linux and Unix HOWTO</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="shell.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 10. Language-Specific Issues</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="java.html"
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>Next</A
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></TD
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></TR
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="ADA"
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></A
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>10.5. Ada</H1
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><P
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>In Ada95, the Unbounded_String type is often more flexible than the
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String type because it is automatically resized as necessary.
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However, don't store especially sensitive secret values such as passwords
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or secret keys in an Unbounded_String, since core dumps and page areas
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might still hold them later.
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Instead, use the String type for this data, lock it into memory
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while it's used, and overwrite the data as
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soon as possible with some constant value such as (others => ' ').
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Use the Ada pragma Inspection_Point on the object holding the secret
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after erasing the memory.
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That way, you can be certain that
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the object containing the secret will really be erased
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(and that the the overwriting won't be optimized away).</P
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><P
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>It's common for beginning Ada programmers to believe that the
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String type's first index value is always 1, but this isn't true if
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the string is sliced.
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Avoid this error.</P
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><P
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>It's worth noting that SPARK is
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a ``high-integrity subset of the Ada programming language'';
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SPARK users use a tool called the ``SPARK Examiner'' to check
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conformance to SPARK rules, including flow analysis, and there are
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various supports for full formal proof of the code if desired.
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<A
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HREF="http://www.sparkada.com"
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TARGET="_top"
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>See the SPARK website for more
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information</A
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>.
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To my knowledge, there are no OSS/FS SPARK tools.
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If you're storing passwords and private keys you should still
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lock them into memory if appropriate
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and overwrite them as soon as possible.
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Note that SPARK is often used in environments where paging does not occur.</P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="shell.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="index.html"
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>Home</A
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><TD
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VALIGN="top"
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><A
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HREF="java.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>Shell Scripting Languages (sh and csh Derivatives)</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="language-specific.html"
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ACCESSKEY="U"
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>Up</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>Java</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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> |