| Commit message (Collapse) | Author | Age | Files | Lines |
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in parallel. On my laptop, a reseed using only process running takes .22 s wall
clock in trunk and .06 s with this change - and that's after increasing the
amount we read by 5 times (by reducing the entropy estimate per byte from .005
bits to 1/1024 bits).
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priorities slightly, pushing netstat -s and netstat -an higher since
they change freqently and don't have a huge amount of output. Use the
-n flag with lsof, which inhibits name lookups which we don't need.
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Fixes for the amalgamation generator for internal headers.
Remove BOTAN_DLL exporting macros from all internal-only headers;
the classes/functions there don't need to be exported, and
avoiding the PIC/GOT indirection can be a big win.
Add missing BOTAN_DLLs where necessary, mostly gfpmath and cvc
For GCC, use -fvisibility=hidden and set BOTAN_DLL to the
visibility __attribute__ to export those classes/functions.
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up during the Fedora submission review, that each source file include some
text about the license. One handy Perl script later and each file now has
the line
Distributed under the terms of the Botan license
after the copyright notices.
While I was in there modifying every file anyway, I also stripped out the
remainder of the block comments (lots of astericks before and after the
text); this is stylistic thing I picked up when I was first learning C++
but in retrospect it is not a good style as the structure makes it harder
to modify comments (with the result that comments become fewer, shorter and
are less likely to be updated, which are not good things).
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Combine the fast and slow polls, into a single poll() operation.
Instead of being given a buffer to write output into, the EntropySource is
passed an Entropy_Accumulator. This handles the RLE encoding that xor_into_buf
used to do. It also contains a cached I/O buffer so entropy sources do not
individually need to allocate memory for that with each poll. When data
is added to the accumulator, the source specifies an estimate of the number
of bits of entropy per byte, as a double. This is tracked in the accumulator.
Once the estimated entropy hits a target (set by the constructor), the
accumulator's member function predicate polling_goal_achieved flips to true.
This signals to the PRNG that it can stop performing polling on sources,
also polls that take a long time periodically check this flag and return
immediately.
The Win32 and BeOS entropy sources have been updated, but blindly; testing
is needed.
The test_es example program has been modified: now it polls twice and outputs
the XOR of the two collected results. That helps show if the output is consistent
across polls (not a good thing). I have noticed on the Unix entropy source,
occasionally there are many 0x00 bytes in the output, which is not optimal.
This also needs to be investigated.
The RLE is not actually RLE anymore. It works well for non-random inputs
(ASCII text, etc), but I noticed that when /dev/random output was fed into
it, the output buffer would end up being RR01RR01RR01 where RR is a random
byte and 00 is the byte count.
The buffer sizing also needs to be examined carefully. It might be useful
to choose a prime number for the size to XOR stuff into, to help ensure an
even distribution of entropy across the entire buffer space. Or: feed it
all into a hash function?
This change should (perhaps with further modifications) help WRT the
concerns Zack W raised about the RNG on the monotone-dev list.
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a Buffered_EntropySource. Data used in the poll is directly accumulated
into the output buffer using XOR, wrapping around as needed. The
implementation uses xor_into_buf from xor_buf.h
This is simpler and more convincingly secure than the method used
by Buffered_EntropySource. In particular the collected data is persisted
in the buffer there much longer than needed. It is also much harder for
entropy sources to signal errors or a failure to collected data using
Buffered_EntropySource. And, with the simple xor_into_buf function, it
is actually quite easy to remove without major changes.
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is requested, Randpool will first do a fast poll on each entropy
source that has been registered. It will count these poll results
towards the collected entropy count, with a maximum of 96
contributed bits of entropy per poll (only /dev/random reaches
this, others measure at 50-60 bits typically), and a maximum of
256 for sum contribution of the fast polls.
Then it will attempt slow polls of all devices until it thinks enough
entropy has been collected (using the rather naive entropy_estimate
function). It will count any slow poll for no more than 256 bits (100 or
so is typical for every poll but /dev/random), and will attempt to collect
at least 512 bits of (estimated/guessed) entropy.
This tends to cause Randpool to use significantly more
sources. Previously it was common, especially on systems with a
/dev/random, for only one or a few sources to be used. This
change helps assure that even if /dev/random and company are
broken or compromised the RNG output remains secure (assuming at
least some amount of entropy unguessable by the attacker can be
collected via other sources).
Also change AutoSeeded_RNG do an automatic poll/seed when it is
created.
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