Hi!
Thanks Rob for your comments. Here are some additional points:
On Sat, 9 Sep 2023 22:07, Robert J. Hansen said:
> and for the vast majority of users isn't worth it. The easy wins (28%
> cost savings on RSA encryption! Whee, almost half a millisecond!) are
The blinding we use for RSA (to mitigate side-channel attacks) should be
in the same range as these wins. I bet that by adding threads to the
computation you will open another can of side-channel attacks.
> performance. I'm sure that if and when the next RFC is officially
> released, there will be interest in getting parallelization support
OCB mode is already used and deployed for years. With a decent
Libgcrypt (1.10) I get these figures for the old (CFB) and the new mode
(OCB)
AES256 | nanosecs/byte mebibytes/sec cycles/byte auto Mhz
CFB enc | 0.691 ns/B 1379 MiB/s 5.14 c/B 7440±1
CFB dec | 0.064 ns/B 14959 MiB/s 0.470 c/B 7372±2
OCB enc | 0.070 ns/B 13547 MiB/s 0.522 c/B 7415±2
OCB dec | 0.071 ns/B 13451 MiB/s 0.520 c/B 7336±3
These values are for the low level crypto routines. In reality we also
do a SHA-1 hashing in addition to CFB which makes it even slower. OTOH.
the protocol requires buffering and the way gpg implements things has a
large impact on the performance. Fortunately, Jussi Kivilinna also
worked on gpg's buffering and gained a lot of extra speed:
* gpg: Threefold decryption speedup for large files.
https://dev.gnupg.org/rGab177eed51 (For the old CFB mode)
* gpg: Nearly double the AES256.OCB encryption speed.
https://dev.gnupg.org/rG99e2c178c7
Thus in 2.4 we get this for symmetric encryption of a 4 GiB file from
RAM to /dev/null on a Ryzen5800X:
AES256.CFB encryption 1.3 GiB/s
AES256.OCB encryption 4.2 GiB/s
FWIW there are also improvements in signature verification:
* gpg: Up to five times faster verification of detached signatures.
Doubled detached signing speed.
https://dev.gnupg.org/rG4e27b9defc
https://dev.gnupg.org/rGf8943ce098
YMMV depending on what kind of data you encrypt, whether signing and
compression comes into the game. Compression is a major performance hog
- feeding gpg from a (threaded) bzip2 and using -z0 will in general give
better performance than the using the internal compressor code.
Shalom-Salam,
Werner
--
The pioneers of a warless world are the youth that
refuse military service. - A. Einstein
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