The GCM test vectors in this directory were downloaded from the NIST
Cryptographic Algorithm Validation Program (CAVP) website
(http://csrc.nist.gov/groups/STM/cavp/) on Mar 29, 2013 using the URL
http://csrc.nist.gov/groups/STM/cavp/documents/mac/gcmtestvectors.zip.

The original test files are about 3 MB each, which are too big to
include in the NSS source tree.  I observed the following patterns in
the test vectors:
1. Taglen changes in a cycle of 7: 128, 120, 112, 104, 96, 64, 32.
2. Then, AADlen changes in a cycle of 5: 0, 128, 160, 384, 720.

To reduce the number of test vectors, I kept Taglen = 128, 96 from
each cycle of 7, and kept AADlen = 0, 720, 160 from each two cycles
of 10.