Comprehensive Analysis: Cryptographic Security Principle and Method

This report provides an analysis of the principle and method in cryptographic security, specifically focusing on the transposition cipher technique. The report explains the concept of transposition ciphers, particularly the double transposition method, and how it works. It describes the process of encryption and decryption using column transposition. The report also discusses the possibility of decrypting messages with different keys, concluding that it is not feasible due to the dependency on keyword length and alphabetical order. Furthermore, the report evaluates the statement that transposition ciphers are not very secure, explaining that these ciphers are vulnerable due to the rearrangement of letters. The report includes references to support the analysis.

Running head: PRINCIPLE AND METHOD IN CRYPTOGRAPHIC SECURITY
Principle and Method in Cryptographic Security
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1PRINCIPLE AND METHOD IN CRYPTOGRAPHIC SECURITY
Explanation of the Encryption Technique:
In this case for the encryption of the message, transposition technique has been utilized.
In the field of cryptography, the method of transposition cipher is a specific type of encryption
process in which specific positions held by the plaintext units are shifted specifically to regular
type of system (Krishna et al., 2016). Thus, the encrypted text or the cipher text consists
permutation of the plaintext that has been encrypted. It means, for the encryption process only
the order of the units are changed and for this reason this type of encryption process does not
provides so much of security. For this type of encryption process a bijetive type of function is
utilized on the position of the characters so that encryption can be done and an inverse function
is also implemented for the decryption process.
For particularly in this case two stage transposition or the double transposition has been
utilized. The double transposition is actually a simple column transposition which is executed
twice. This type of text transposition is quite safe when compared with the other type of
encryption process (Budiman & Rachmawati, 2018). The column transposition cipher is a
specific type of form of the transposition cipher. In this case, this type of transposition is
executed by writing the plain texts in the rows and then the cipher text is achieved off the
columns in one by one manner. In the following section this technique is described briefly.
The two stage transposition is consisting two applications of the column transposition.
Both of the applications can use a similar key for each of the applications or different types of
keys can be used. To execute this type of encryption first a key is chosen for the first column
transposition, In this case the message which need to be encrypted, need to be written under the
rows of key word (Priyam, 2015). After that numbering of the letters need to be done which are

2PRINCIPLE AND METHOD IN CRYPTOGRAPHIC SECURITY
present in the key word and this numbering will be done depending on the alphabetical order.
Now the cipher texts are extracted from table off by columns and this is done by starting with the
column which is having the lowest number. At this stage, the first column transposition is done.
Now, a second key word need to be selected. Under this second key word, cipher texts achieved
from the first column transposition need to be placed like the previous case and the same
operations done for the first columnar transposition need to be executed again for the second
columnar transposition. This type of encrypted texts cannot be decrypted without having those
predetermined key words. For decryption of this type of cipher texts a block need to be created
having the right number of rows under the keyword, blocking off the columns which are short in
nature (Ramya et al., 2016). After that, the ciphers texts needs to be written in columns and
reading need to be done by the rows. The whole process need to be done again with the other key
word for full decryption of the text.
Possibility of decrypting message with different key:
Considering this type of encryption technique, it is not possible to decrypt the message
with some different keys. The main reason that the message cannot be decrypted using some
different type of keyword is the length of the keyword and the alphabets used in the keyword and
the order of these alphabets. In this case if some other keyword is chosen which is having
different length then it is not possible to decrypt the message as the gathered output will not have
any type of meaning (Horel et al., 2018). Now if it is considered that chosen keyword is different
but having the similar length with the original keyword, still it is not possible to decrypt the
message due to alphabetical order of the keyword. If the alphabetical order is not the same in this
then generated number from the keyword will be different which will be ultimately leading to
decryption of something that is not having any type of meaning.

3PRINCIPLE AND METHOD IN CRYPTOGRAPHIC SECURITY
Discussion on the statement of the message:
In the statement it is defined that cipher technique is executed by permuting the letters of
the plain texts and this type of techniques are not so secure in nature. Here the statement of the
above section is right as transposition ciphers really utilises the letters of the plaintext message
and permute the order of the letter (Lasry, Kopal & Wacker, 2016). This type of ciphers provides
very weak security as for the encryption of the texts, only the alphabets of a word is rearranged
which can be spotted easily. One of the simple transposition cipher is reversing the letters of the
plaintext. For example, if this type of encryption is applied on the plaintext “General Store” then
the encrypted text will be “EROTS LARENEG”. By observing this encrypted text properly, it
can be decrypted easily and for this reason this type of encryption fails to provide adequate
security.

4PRINCIPLE AND METHOD IN CRYPTOGRAPHIC SECURITY
References:
Budiman, M. A., & Rachmawati, D. (2018, March). Implementation of Super-Encryption with
Trithemius Algorithm and Double Transposition Cipher in Securing PDF Files on
Android Platform. In Journal of Physics: Conference Series (Vol. 978, No. 1, p. 012088).
IOP Publishing.
Horel, T., Park, S., Richelson, S., & Vaikuntanathan, V. (2018). How to subvert backdoored
encryption: security against adversaries that decrypt all ciphertexts. arXiv preprint
arXiv:1802.07381.
Krishna, B. H., Reddy, I. R. S., Kiran, S., & Reddy, R. P. K. (2016, March). Multiple text
encryption, key entrenched, distributed cipher using pairing functions and transposition
ciphers. In 2016 International Conference on Wireless Communications, Signal
Processing and Networking (WiSPNET) (pp. 1059-1061). IEEE.
Lasry, G., Kopal, N., & Wacker, A. (2016). Cryptanalysis of columnar transposition cipher with
long keys. Cryptologia, 40(4), 374-398.
Priyam, A. (2015). Extended Vigenère using double Transposition Cipher with One Time Pad
Cipher. Intl J Engg Sci Adv Research, 1(2), 62-65.
Ramya, C. P., Vipin, K. M., Mareena, M., Ramya, C. P., Vipin, K. M., & Mareena, M. (2016).
Keyword Search on Public Key Ciphertexts with Reduced Overhead using a Query Based
Ranking System. International Journal, 3, 69-73.