Libgcrypt may be used in a FIPS 140-2 mode. Note, that this does not necessary mean that Libcgrypt is an appoved FIPS 140-2 module. Check the NIST database at http://csrc.nist.gov/groups/STM/cmvp/ to see what versions of Libgcrypt are approved.
Because FIPS 140 has certain restrictions on the use of cryptography which are not always wanted, Libgcrypt needs to be put into FIPS mode explicitly. Three alternative mechanisms are provided to switch Libgcrypt into this mode:
0, Libgcrypt is put into FIPS mode at initialization time. Obviously this works only on systems with a
procfile system (i.e. GNU/Linux).
GCRYCTL_FORCE_FIPS_MODE. This must be done prior to any initialization (i.e. before
In addition to the standard FIPS mode, Libgcrypt may also be put into
an Enforced FIPS mode by writing a non-zero value into the file
/etc/gcrypt/fips_enabled or by using the control command
GCRYCTL_SET_ENFORCED_FIPS_FLAG before any other calls to
libgcrypt. The Enforced FIPS mode helps to detect applications
which don't fulfill all requirements for using
Libgcrypt in FIPS mode (see FIPS Mode).
Once Libgcrypt has been put into FIPS mode, it is not possible to switch back to standard mode without terminating the process first. If the logging verbosity level of Libgcrypt has been set to at least 2, the state transitions and the self-tests are logged.