Lee McKenna
Mon Nov 19 18:46:01 2001

Werner Koch wrote:

>On Mon, 19 Nov 2001 09:17:25 -0600, Lee McKenna said:
>>I have tried different key lengths (768 - 2048) and I've tried every
>>cipher available to try to improve performance, but I get about the
>The keylength does not matter for large files.  Only the performance
>of the symmetric cipher algorithm counts.  It depends on the recipients
>preference which algorithm is chosen, to get more reliable numbers you
>should use "gpg -c --cipher <algo>".  Try 3DES, BLOWFISH and AES - I
>have no benchmarks for large files - I can only remember that it took
>quite long to test the large file support ;-)
>>Any suggestions on improving performance?
>RIJNDAEL should be the fasted.  You may want to tweak the IOBUFs (grep
>for iobuf_alloc in util/iobuf.c) or the hash buffers (cipher/md.c
A little background info...we maintain over 1 TB of large encrypted 
files, with 50-75GB new each month.  gnupg has been working wonderfully 
for over a year now on our large files, I think the largest has been 
over 7GB, while the average is 3.5GB.  I'm not really complaining too 
much about performance, but we do have one "business" instance whereby 
it would be "nice" if it was maybe twice the speed it currently is :)

For the record book :) I ran the following tests using gpg 1.0.6, 
1024bit key, on a PIII/800, 256MB RAM, SCSI/IDE RAID, stock FreeBSD 4.3 
release, on a file size 3363088179 (3.3GB).  CAST5 is the fastest, 3DES 
slowest.  All others are relatively close.

The file is an MPEG2 movie.  We've experimented with compression -z 
options, but we found it of no use on these MPEG2 files (in fact, 
detrimental to speed and file size), hence the -z0 in our script.

Here is a snipet of the test script I used so you can see the gpg 
command syntax:

echo -e '\n3DES encrypt' >>timer.dat
/usr/bin/time -a -h -o timer.dat cat 23054.mpg | gpg -e -z0 -o 
23054.mpg.3DES.gpg --cipher-algo 3DES -r content
echo -e '\n3DES decrypt' >>timer.dat
/usr/bin/time -a -h -o timer.dat gpg -v -d -o 23054.mpg.3DES.decrypted 

Here is the output file timer.dat:

3DES encrypt
        15m3.50s real           0.21s user              18.73s sys

3DES decrypt
        18m45.87s real          17m54.32s user          41.26s sys

CAST5 encrypt
        9m11.62s real           0.20s user              20.35s sys

CAST5 decrypt
        9m59.68s real           8m59.71s user           42.02s sys

BLOWFISH encrypt
        9m44.20s real           0.27s user              19.47s sys

BLOWFISH decrypt
        11m28.13s real          10m39.52s user          40.37s sys

RIJNDAEL encrypt
        9m18.35s real           0.27s user              19.80s sys

RIJNDAEL decrypt
        11m15.23s real          10m26.04s user          41.63s sys

RIJNDAEL192 encrypt
        9m31.82s real           0.23s user              19.51s sys

RIJNDAEL192 decrypt
        11m45.56s real          10m55.74s user          42.09s sys

RIJNDAEL256 encrypt
        9m45.13s real           0.21s user              19.65s sys

RIJNDAEL256 decrypt
        12m21.69s real          11m26.39s user          42.01s sys

TWOFISH encrypt
        9m38.59s real           0.22s user              19.46s sys

TWOFISH decrypt
        11m28.03s real          10m37.77s user          41.13s sys

768bit RIJNDAEL256 encrypt
        9m32.32s real           0.26s user              19.57s sys

768bit RIJNDAEL256 decrypt
        12m32.70s real          11m30.50s user          40.94s sys

Symetric (-c) RIJNDAEL256 decrypt
        10m2.10s real           0.24s user              19.89s sys

Symetric (-c)  RIJNDAEL256 decrypt
        12m19.85s real          11m28.25s user          42.16s sys