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More number for the questions about SSL overheads....
The following numbers were generated on a pentium pro 200, running linux.
They give an indication of the SSL protocol and encryption overheads.
The program that generated them is an unreleased version of ssl/ssltest.c
which is the SSLeay ssl protocol testing program. It is a single process that
talks both sides of the SSL protocol via a non-blocking memory buffer
How do I read this? The protocol and cipher are reasonable obvious.
The next number is the number of connections being made. The next is the
number of bytes exchanged bewteen the client and server side of the protocol.
This is the number of bytes that the client sends to the server, and then
the server sends back. Because this is all happening in one process,
the data is being encrypted, decrypted, encrypted and then decrypted again.
It is a round trip of that many bytes. Because the one process performs
both the client and server sides of the protocol and it sends this many bytes
each direction, multiply this number by 4 to generate the number
of bytes encrypted/decrypted/MACed. The first time value is how many seconds
elapsed doing a full SSL handshake, the second is the cost of one
full handshake and the rest being session-id reuse.
SSLv2 RC4-MD5 1000 x 1 12.83s 0.70s
SSLv3 NULL-MD5 1000 x 1 14.35s 1.47s
SSLv3 RC4-MD5 1000 x 1 14.46s 1.56s
SSLv3 RC4-MD5 1000 x 1 51.93s 1.62s 1024bit RSA
SSLv3 RC4-SHA 1000 x 1 14.61s 1.83s
SSLv3 DES-CBC-SHA 1000 x 1 14.70s 1.89s
SSLv3 DES-CBC3-SHA 1000 x 1 15.16s 2.16s
SSLv2 RC4-MD5 1000 x 1024 13.72s 1.27s
SSLv3 NULL-MD5 1000 x 1024 14.79s 1.92s
SSLv3 RC4-MD5 1000 x 1024 52.58s 2.29s 1024bit RSA
SSLv3 RC4-SHA 1000 x 1024 15.39s 2.67s
SSLv3 DES-CBC-SHA 1000 x 1024 16.45s 3.55s
SSLv3 DES-CBC3-SHA 1000 x 1024 18.21s 5.38s
SSLv2 RC4-MD5 1000 x 10240 18.97s 6.52s
SSLv3 NULL-MD5 1000 x 10240 17.79s 5.11s
SSLv3 RC4-MD5 1000 x 10240 20.25s 7.90s
SSLv3 RC4-MD5 1000 x 10240 58.26s 8.08s 1024bit RSA
SSLv3 RC4-SHA 1000 x 10240 22.96s 11.44s
SSLv3 DES-CBC-SHA 1000 x 10240 30.65s 18.41s
SSLv3 DES-CBC3-SHA 1000 x 10240 47.04s 34.53s
SSLv2 RC4-MD5 1000 x 102400 70.22s 57.74s
SSLv3 NULL-MD5 1000 x 102400 43.73s 31.03s
SSLv3 RC4-MD5 1000 x 102400 71.32s 58.83s
SSLv3 RC4-MD5 1000 x 102400 109.66s 59.20s 1024bit RSA
SSLv3 RC4-SHA 1000 x 102400 95.88s 82.21s
SSLv3 DES-CBC-SHA 1000 x 102400 173.22s 160.55s
SSLv3 DES-CBC3-SHA 1000 x 102400 336.61s 323.82s
What does this all mean? Well for a server, with no session-id reuse, with
a transfer size of 10240 bytes, using RC4-MD5 and a 512bit server key,
a pentium pro 200 running linux can handle the SSLv3 protocol overheads of
about 49 connections a second. Reality will be quite different :-).
Remeber the first number is 1000 full ssl handshakes, the second is
1 full and 999 with session-id reuse. The RSA overheads for each exchange
would be one public and one private operation, but the protocol/MAC/cipher
cost would be quite similar in both the client and server.
eric (adding numbers to speculation)
--- Appendix ---
- The time measured is user time but these number a very rough.
- Remember this is the cost of both client and server sides of the protocol.
- The TCP/kernel overhead of connection establishment is normally the
killer in SSL. Often delays in the TCP protocol will make session-id
reuse look slower that new sessions, but this would not be the case on
a loaded server.
- The TCP round trip latencies, while slowing indervidual connections,
would have minimal impact on throughput.
- Instead of sending one 102400 byte buffer, one 8k buffer is sent until
- the required number of bytes are processed.
- The SSLv3 connections were actually SSLv2 compatable SSLv3 headers.
- A 512bit server key was being used except where noted.
- No server key verification was being performed on the client side of the
protocol. This would slow things down very little.
- The library being used is SSLeay 0.8.x.
- The normal mesauring system was commands of the form
time ./ssltest -num 1000 -bytes 102400 -cipher DES-CBC-SHA -reuse
This modified version of ssltest should be in the next public release of
The general cipher performace number for this platform are
SSLeay 0.8.2a 04-Sep-1997
built on Fri Sep 5 17:37:05 EST 1997
options:bn(64,32) md2(int) rc4(idx,int) des(ptr,risc1,16,long) idea(int) blowfish(ptr2)
C flags:gcc -DL_ENDIAN -DTERMIO -O3 -fomit-frame-pointer -m486 -Wall -Wuninitialized
The 'numbers' are in 1000s of bytes per second processed.
type 8 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes
md2 131.02k 368.41k 500.57k 549.21k 566.09k
mdc2 535.60k 589.10k 595.88k 595.97k 594.54k
md5 1801.53k 9674.77k 17484.03k 21849.43k 23592.96k
sha 1261.63k 5533.25k 9285.63k 11187.88k 11913.90k
sha1 1103.13k 4782.53k 7933.78k 9472.34k 10070.70k
rc4 10722.53k 14443.93k 15215.79k 15299.24k 15219.59k
des cbc 3286.57k 3827.73k 3913.39k 3931.82k 3926.70k
des ede3 1443.50k 1549.08k 1561.17k 1566.38k 1564.67k
idea cbc 2203.64k 2508.16k 2538.33k 2543.62k 2547.71k
rc2 cbc 1430.94k 1511.59k 1524.82k 1527.13k 1523.33k
blowfish cbc 4716.07k 5965.82k 6190.17k 6243.67k 6234.11k
sign verify
rsa 512 bits 0.0100s 0.0011s
rsa 1024 bits 0.0451s 0.0012s
rsa 2048 bits 0.2605s 0.0086s
rsa 4096 bits 1.6883s 0.0302s
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