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agent: compile-time configuration of s2k calibration. 

* configure.ac: add --with-agent-s2k-calibration=MSEC, introduces
AGENT_S2K_CALIBRATION (measured in milliseconds)
* agent/protect.c (calibrate_s2k_count): Calibrate based on
AGENT_S2K_CALIBRATION.

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
GnuPG-bug-id: 3399
This commit is contained in:
Daniel Kahn Gillmor 2017-09-08 17:08:57 -04:00
parent 73ff075204
commit 926d07c5fa
2 changed files with 12 additions and 4 deletions
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6
agent/protect.c
View File

@ -159,7 +159,7 @@ calibrate_s2k_count_one (unsigned long count)
/* Measure the time we need to do the hash operations and deduce an
S2K count which requires about 100ms of time. */
S2K count which requires roughly some targeted amount of time. */
static unsigned long
calibrate_s2k_count (void)
{
@ -171,11 +171,11 @@ calibrate_s2k_count (void)
ms = calibrate_s2k_count_one (count);
if (opt.verbose > 1)
log_info ("S2K calibration: %lu -> %lums\n", count, ms);
if (ms > 100)
if (ms > AGENT_S2K_CALIBRATION)
break;
}
count = (unsigned long)(((double)count / ms) * 100);
count = (unsigned long)(((double)count / ms) * AGENT_S2K_CALIBRATION);
count /= 1024;
count *= 1024;
if (count < 65536)

10
configure.ac
View File

@ -122,7 +122,6 @@ use_tls_library=no
large_secmem=no
show_tor_support=no
GNUPG_BUILD_PROGRAM(gpg, yes)
GNUPG_BUILD_PROGRAM(gpgsm, yes)
# The agent is a required part and can't be disabled anymore.
@ -250,6 +249,15 @@ fi
AC_DEFINE_UNQUOTED(SECMEM_BUFFER_SIZE,$SECMEM_BUFFER_SIZE,
[Size of secure memory buffer])
AC_MSG_CHECKING([calibrated passphrase-stretching (s2k) duration])
AC_ARG_WITH(agent-s2k-calibration,
AC_HELP_STRING([--with-agent-s2k-calibration=MSEC],
[calibrate passphrase stretching (s2k) to MSEC milliseconds]),
agent_s2k_calibration=$withval, agent_s2k_calibration=100)
AC_MSG_RESULT($agent_s2k_calibration milliseconds)
AC_DEFINE_UNQUOTED(AGENT_S2K_CALIBRATION, $agent_s2k_calibration,
[Agent s2k calibration time (ms)])
AC_MSG_CHECKING([whether to enable trust models])
AC_ARG_ENABLE(trust-models,
AC_HELP_STRING([--disable-trust-models],