IEEE Consumer Electronics Magazine - January/February 2022 - 44

Metaheuristic Methods Can Decrease the Probability of Weak Keys Being Generated
Table 1. Comparison of encryption methods.
Name Encryption categories Computing time Weak key Common scenarios
DES
3DES
AES
RSA
DSA
SHA
MD5
symmetric
symmetric
symmetric
asymmetric
asymmetric
hash-based
hash-based
shortest
longer
short
longer
short
longest
short
√
√
√
√
single user
single user
single user
multiple user
multiple user
digital signature
digital signature
security. Unfortunately, it can only apply to digital
signatures. Hash-based encryption is another system.
Strictly speaking, they cannot be regarded as
an encryption method. This is because hash-based
encryption like secure hash algorithm (SHA) and
message-digest algorithm (MD5) focus on using
one-way ciphertext to ensure the integrity of the
data, but cannot reverse the ciphertext to the
plaintext. Table 1 lists the abovementioned three
types of encryptionmethods.
Although these methods have been widely
used, they still cannot guarantee 100% safety. A
fatal key issue is that the process of key generation
is so linear and regular that the weak key has a certain
chance of being generated. To mitigate this
defect, asymmetric encryption can use a limited
time decryption mechanism as well as hash-based
encryption can increase the length of bytes as
much as possible to shorten the time that malicious
user try to decipher. But symmetric encryption
is difficult to deal with this severe test.
However, in the field of consumer electronics,
most of services need to have a very fast response
time to maintain the consumer experience; hence,
many consumer electronic products choose DES
as themain encryptionmethod. Allinall, inorder
to solve the security problem of generating weak
keys due to too regular rules in the key generation
process, we will propose a method that can effectively
improve the randomness.
PROBLEM DEFINITION AND
SIMILARITY MODEL DESIGN
The major problem is that the traditional
encryption methods cannot avoid the generating
of weak keys. There are scholars that have begun
to try the metaheuristic algorithm which has the
44
Figure 1. Key similarity model based on area.
References
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random nature to solve this problem. The main
purpose of this type of algorithm is to search for
the optimal solution. But it is difficult to define
what is optimum in the problemof key generation.
So they can only regard Shannon entropy as the fitness
function. However, the fitness function based
on Shannon entropy still cannot effectively rule
out the generation of continuous keys. This is
because although Shannon entropy can make one
bit of the two strings different, it does not consider
the translation of the bit, which means that if a
malicious user uses the original text as a starting
point for brute force cracking, the ciphertext will
soon be deciphered.
We must first outline the phenomenon of weak
keys. In Figure 1, a 10 lengths plaintext is shown by
the blue line. The number corresponding to each
index represents the ASCII value of the content.We
can see that index 1 to index 3 of the cyan line is
almost similar to the plaintext line. As well as index
5 to index 10 also have this phenomenon. It can be
found through observation that the mentioned
part of the cyan line is basically just the result of
the basic translation of the plaintext. We can find
that the number of blocks formed by these two
curves is very few, and the total area is also very
small. It means that these two lines are very similar,
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