Uzamsal Alanda Bir Kripto-Stegano Hibrit Uygulama

Yıl 2022, Cilt: 5 Sayı: 2, 154 - 164, 31.12.2022

Hüseyin Bilal Macit

https://doi.org/10.55117/bufbd.1100693

Öz

Gelişen teknoloji ile birlikte iletişimde veri güvenliği ihtiyacı artmaktadır. Veri güvenliğini sağlamanın en iyi yolu kriptografidir. İnsanlık yüzlerce yıldır birçok kriptografi yöntemi önerdi. Günümüzde oldukça güvenli ancak yüksek işlem gücü gerektiren karmaşık şifreleme algoritmaları bulunmaktadır. Geçmişte kullanılan şifreleme teknikleri daha az güvenlidir ancak daha az işlem gücü gerektirir. Bu makale, eski bir şifreleme yöntemi olan Vigenère şifresinin geliştirilmiş bir versiyonunu önermektedir. Geliştirilmiş Vigenère şifresi ile oluşturulan şifre metni, iletim ortamında güvende tutmak için bir görüntüde de gizlenir. Gizleme işlemi, bir diğer veri güvenliği yöntemi olan steganografi ile gerçekleştirilir. Böylece hem şüpheden uzak hem de güvenli bir iletişim yöntemi ortaya çıkmıştır. Önerilen yöntemin kriptolojik güvenliği Avalanche etkisi ölçülmüş, steganografik güvenliği ise SSIM ve PSNR ölçümleri ile değerlendirilmiştir.

Anahtar Kelimeler

Vigenère tablosu, Vigenère şifreleme, Steganografi, Çığ etkisi

A Crypto-Stegano Hybrid Application on Spatial Domain

Öz

The need for data security in communication is increasing with the developing
technology. The best way to ensure data security is cryptography. Humanity has
proposed many cryptography methods for hundreds of years. Today, there are
complex cryptography algorithms, which are quite secure but require high processing
power. Cryptography techniques used in the past are less secure but require less
processing power. This article proposes an extended version of the Vigenère cipher,
which is an ancient encryption method. Extended Vigenère cipher is able to encrypt
upper and lower case letters, numeric characters, and punctuation marks. In addition,
the method can use upper and lower case letters, numeric characters and punctuation
marks as encryption key, and there is no key length limit. The cipher text generated
with the extended Vigenère cipher is also hidden in an image to keep it safe in the
transmission medium. Hiding is performed with LSB steganography, which is
another data security method. Thus, both the readability and detectability of
confidential data are reduced. The cryptological security of the proposed method is
measured by the Avalanche effect. Steganographic safety is evaluated with SSIM
and PSNR measurements. A user graphical interface has been developed and the
maximum payload of the carrier image is measured before encryption. Proposed
method applied on some test images with different specifications. 1 bit key
modification avalanche effect results of proposed method with random plain texts
between 1000-10000 characters with a key length of 8 and 16 characters is close to
50%. Also, SSIM value calculated over 0.99 each time while maximum
steganographic payload of the test images reached.

Anahtar Kelimeler

Vigenère table, Vigenère cipher, Steganography, Avalanche effect

Kaynakça

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