Virtual vpn in the cloud

4.3.4
 
Software for Performance Metrics 
Iperf
[35] is a network-testing tool/network performance measurement tool with the 
capability of creating TCP and UDP streams and measures the throughput of the network 
carrying them. Written in C language it enables the user to set various parameters required 
for testing the network. It has client and server functionality to measure the throughput 
across the two ends, either unidirectional or bi-directional. 
Iperf
reports throughput, jitter and 
packet loss. TCP and UDP analysis have been calculated with the 
iperf
tool and resulting 
statistics are deduced. 

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27 
5
 
R
ESULTS
 
This section involves a detailed study on different combinations of encryption and hashing 
algorithms considered in the experimental procedure to determine the cryptographic, metric 
and overhead analysis involved in each case. The different encryption algorithms considered 
are AES526, AES128 and 3DES; the hashing algorithms considered are SHA256 and MD5. 
The parameters considered are TCP throughput, UDP throughput, and jitter and packet loss. 
These parameters are measured for different MTU values to understand the impact of packet 
size on overheads. Comparative analyses on tunneled and non-tunneled traffic are computed 
to determine the overhead of encryption in a virtualized environment. All the measurements 
are plotted with 95% confidence intervals.
5.1
 
Brief description of Algorithms
 
5.1.1
 
Advanced Encryption Standard 
AES comprises of variable length ciphers including 128-bit and 256-bit key length 
ciphers. Each cipher encrypts and decrypts data in blocks of 128 and 256 bits using 128-
bit and 256-bit cryptographic keys respectively. Due to its high computational 
complexity, AES is considered to be of high speed and reliability assuming the 
approximate cipher cracking time to be 149 trillion years [36] [37].