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Inspired by comments from Jeffrey Walton in: https://lists.gnu.org/r/bug-gnulib/2020-06/msg00002.html * doc/glibc-functions/getentropy.texi (getentropy): * doc/glibc-functions/getrandom.texi (getrandom): Improve discussion of problems with "random" data, and cite Ristenpart & Yilek. Also, mention GRND_INSECURE.
52 lines
1.6 KiB
Plaintext
52 lines
1.6 KiB
Plaintext
@node getrandom
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@subsection @code{getrandom}
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@findex getrandom
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Documentation:
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@itemize
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@item
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@ifinfo
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@ref{Unpredictable Bytes,,Generating Unpredictable Bytes,libc},
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@end ifinfo
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@ifnotinfo
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@url{https://www.gnu.org/software/libc/manual/html_node/Unpredictable-Bytes.html},
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@end ifnotinfo
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@item
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@uref{https://www.kernel.org/doc/man-pages/online/pages/man2/getrandom.2.html,,man getrandom}.
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@end itemize
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Gnulib module: getrandom
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Portability problems fixed by Gnulib:
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@itemize
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@item
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This function is missing on some platforms:
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glibc 2.24, Mac OS X 10.5, FreeBSD 11.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, Solaris 11.0, Cygwin, mingw, MSVC 14, Android 9.0.
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@item
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This function has a different return type on some platforms:
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Solaris 11.4.
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@end itemize
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Portability problems not fixed by Gnulib:
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@itemize
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@item
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The @code{GRND_INSECURE} flag is missing on some platforms:
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glibc 2.31, macOS 10.15, GNU/kFreeBSD, FreeBSD 12.0, OpenBSD 6.5,
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Minix 3.3, Haiku.
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@item
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The @code{GRND_RANDOM} flag has different effects on different platforms.
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Some platforms ignore the flag, or yield data that can fail to be
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random in some cases.
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@end itemize
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@noindent
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Although this function is intended to produce random data, the data's
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security properties may not be appropriate for your application.
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For example, identical ``random'' data streams might be produced by
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rebooted virtual machines. If this is of concern you may need to use
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additional techniques such as hedging.@footnote{Ristenpart T, Yilek
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S@. @url{http://pages.cs.wisc.edu/~rist/papers/sslhedge.pdf, When good
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randomness goes bad: virtual machine vulnerabilities and hedging
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deployed cryptography}. NDSS 2010.}
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