INTRODUCTION TO CRYPTOGRAPHY
Cryptography is the branch of science that deals with data security relating to encryption and decryption. This science has been in existence about 4000 years ago with its initial and limited use by the Egyptians, to the twentieth century where it played a crucial role in the outcome of both world wars. Cryptography was used as a tool to protect national secrets and strategies. DES, the Data Encryption Standard, is an adoption with the Federal Information Processing Standard for encrypting unclassified information, is the most well-known cryptographic mechanism in the history. It remains the standard means for securing electronic commerce for many financial institutions around the world. The two most basic terms related to cryptography are Encryption and Decryption. These terms play a crucial role in bringing up this topic, and have been discussed in detail. The other terms that are crucial related to this topic is Secret Keys and Ciphers (upon which our entire report is based).
ENCRYPTION AND DECRYPTION
As said earlier, Encryption and Decryption are the two most basic terms of Cryptography. Here, the secret is to convert the plain text, which is the usual text that we encounter daily, into a Cipher text which on sight looks just like a ordinary plain text but with a secret message hidden which can be only read by the person who knows the secret behind the new text. The above situation can be termed as Encryption and Decryption. The term Encryption means to convert the plain text into the Cipher text and Decryption means to convert the Cipher text back to plain text. Both Encryption and Decryption are done using a secret key or symmetric key which is usually possessed only by the one who encrypts and by the one who decrypts. Figure 1-1 shows us the basic diagram of the encryption and decryption process.
Figure 1-2 shows the conventional encryption which even includes the secret key....
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