Cryptography

Pabitra Bansal
Sep 9, 2018 · 2 min read

The word cryptography is derived from the Ancient Greek word kryptos which translates to secrete or hidden (from- http://www.herongyang.com/Cryptography/Concept-What-Is-Cryptography.html). Cryptography is techniques used to keep communications private and secure.

One of the first use of cryptography dates back to 50BC when Julias Ceasar used a cypher ( an algorithm used to convert plaintext to some code not readable as such) where he shifted each letter by 3 in the Roman alphabets. He had done it since he did not trust his messengers and didn’t want them to read the messages meant to higher authorities.

Source:http://treasures2remember.com/wp-content/uploads/2016/11/RW013.jpg

Today being an era of computers and internet cryptography plays a significant role in maintaining our privacy and security.

Cryptography methods include hiding text in an image, using a cypher to create an encrypted version, etc. Three widely used types of cryptographic algorithms are:

1.Secret Key Cryptography(SKC): In this case, “a key is shared between the sender and receiver which is used for both encrypting and decrypting the message” (https://nnc3.com/mags/Networking2/tcp/ch12_06.htm). The algorithm to generate such a shared key is given by the Diffie-Hellman key exchange which is done using the concept of modular exponentiation.SKC is also known as symmetric encryption.

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2.Public Key Cryptography(PKC): In this case, there are two different keys one of them is public(can be viewed by anyone), and the other is a private key(only the owner knows about it), something encrypted using the public key can be decrypted only by using the private key. So while sending the message, the sender encrypts it using the public key of who is supposed to receive it, and the receiver then decrypts it using its private key. PKC is also known as asymmetric encryption.

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3.Hash Functions: These functions are used to check if there is a change in the original message or not. Hash functions take in a message and give a fixed size string as output. They do not use any key and are also known as one-way encryption.

Source:https://kifanga.com
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