Virtual vpn in the cloud

5.1.2
 
Triple Data Encryption Standard 
With the expanding computer processing power, the 56-bit DES algorithm is considered 
inadequate to keep data secure for a longer period. It is referred to as 
3DES, 
since it 
encrypts the data three times each with different keys increasing the productivity of the 
same algorithm. Each has a 64-bit key length, summing it to a 192-bit symmetric key 
algorithm. Despite its slow speed, the approximate cracking time of this algorithm is 
considered to be 4.6 billion years with current technology [36] [37]. 
 
5.1.3
 
Secure Hash Algorithm 
SHA2 [38, p. 2] stands for 2
nd
version of Secure Hash Algorithm designed to overcome 
the vulnerabilities imposed by the 1
st
version, SHA1. SHA2 is a cryptographic hash 
function with a digest length of 256 bits. In comparison to SHA1, SHA2 is considered 
stronger and longer hashes are generated for data security. 
5.1.4
 
Message Digest Algorithm 
MD5 stands for Message Digest Algorithm 5, which verifies data integrity through the 
creation of a 128-bit message digest from data input of any length [39, p. 5]. Despite 
being slower in comparison to MD4, it offers higher assurance of data security. 
 
5.2
 
Results for TCP traffic 
The bandwidth for different combinations of encryption and hashing algorithms are 
reviewed for different MTU sizes. Each measurement has been iterated 30 times with a 
time period of 10 seconds each. The TCP congestion control algorithm used for this 
research is the default 
CUBIC. 
This algorithm is considered to be a less aggressive 
variant of BIC that is Binary Increase Congestion Control. In TCP, different packet sizes 
with MTU 1500, 1000, 500 and 250 are considered. Graphs are plotted at different 
MTUs against their achieved throughputs for different algorithms. Non-tunneled traffic 

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indicates the traffic measured for plaintext data and the tunnel traffic using different 
encryption algorithms for cipher text data.