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b'hello every one my name is vijay kumar deviredy and i am glad to have you on my episode 03 today we are going to disscuss about how to protect your information in the internet world\\xa0\\n\\nwith the help of cryptography before going into deep let see where it is started with little drama.\\n\\nIn 1586, Mary, Queen of Scots,was convicted of treason against Queen Elizabeth.She was found guilty of plotting to overthrow the English monarch,and not long afterwards she was\\xa0\\n\\nbeheaded.Did you know that the evidence that convicted her was obtained by the English spymaster\'s ability to break Mary\'s secret correspondence\\n\\nwith her supporters? What can we learn from this drama? Well, that you better know how to protect your secrets.\\n\\nWhen we started discussing information security,\\n\\nwe learned that there are two types of parties involved. The defenders and the adversaries.we call it as attackers\\n\\nThe defenders have a variety of goals that they need to achieve,and the adversaries try to disrupt their efforts.\\n\\nIn this episode we will focus on the confidentiality defensive goal,and on attacks against it.\\n\\nThe techniques used to achieve both defensive and offensive goals belong to the body of knowledge\\n\\ncalled cryptography.The word "cryptography" comes from ancient Greek, and translates to "secret writing".\\n\\nCryptography also includes solutions to more advanced goals, like digital signatures and key exchange,\\n\\nwhich we will discuss in a later episodes which will be a continuation of this .The starting point of the confidentiality goal\\n\\nis that our defender, who we shall call lara , has some secret information.But just having a secret\\xa0\\n\\nis not very interesting right.lara needs to send this information,as a secret message, to rakesh,who is also on\\xa0\\n\\nthe defenders\' side.The idea of a secret message implicitly introduces the adversary,who we shall call vijay.vijay can eavesdrop on the communications between lara and rakesh.\\n\\nSo, lara needs a wayto send a secret message to rakesh,in a way that rakesh will understand,but vijay will not,\\n\\ndespite the fact that vijay can hear,or read, the communicated message.In the 1587 drama,Mary played the role of lara,her supporters were rakesh,and Queen Elizabeth\'s spymaster played vijay,\\n\\nTo achieve their joint goal,lara and rakesh need to agree upon a special communication mechanism that is resistant to eavesdropping.\\n\\nThe mechanism lara usesto construct the secret message is called encryption.rakesh uses the inverse mechanism, decryption. Together, the encryption and decryption mechanisms\\n\\nform a cryptographic primitive called a cipher.More specifically, a symmetric cipher.A cryptographic primitiveis a cryptographic capability, or mechanism,that can be used by itself,\\n\\nand can also be used as a building block in a larger context.Symmetric ciphers are the firstcryptographic primitive we will learn about.\\n\\nWe will meet more primitives later in the continuation episodes. until then take rest and beaware about what we had discussed in episode and thankyou...'