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The security of the cryptographic techniques heavily relies on strong encryption and decryption algorithms and increased complexity associated to the algorithms. In this book the plaintext message is converted to the ciphertext message by using both RSA as asymmetric key algorithm and one-time pad as symmetric key algorithm. Three levels of encryption processes are imposed to produce a ciphertext which for sending to the receiver. First, the original message is encrypted by the private key of RSA algorithm of the sender then the output of the first encryption is again encrypted with the public key RSA algorithm of the receiver and finally the output of the second encryption is further encrypted by a shared secret key of one-time pad algorithm. After the above three encryptions a final ciphertext is generated and then sent to the receiver through the communication channels.

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Anisur Rahman is a Senior Lecturer in Computer Science & Engineering Department at Daffodil International University. He has an MSc in Computer Science & Engineering from Daffodil International University. His interst areas include Networking and Security System.

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