Define CIA triad. State the encryption process of double and triple DES. What is the task of S-Box in DES ? Discuss with an example.

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Suresh Chand · Accepted Answer

The CIA triad is one of the most important models which is designed to guide policies for information security within an organization. CIA stands for : Confidentiality Integrity Availability 1. Confidentiality: It is roughly equivalent to privacy. Confidentiality measures are designed to prevent sensitive information from unauthorized access attempts. It is common for data to be categorized according to the amount and type of damage that could be done if it fell into the wrong hands. More or less stringent measures can then be implemented according to those categories. 2. Integrity: It involves maintaining the consistency, accuracy, and trustworthiness of data over its entire lifecycle. Data must not be changed in transit, and steps must be taken to ensure data cannot be altered by unauthorized people (for example, in a breach of confidentiality). 3. Availability: It means information should be consistently and readily accessible to authorized parties. This involves properly maintaining hardware and technical infrastructure and systems that hold and display the information. Encryption in Double DES: Given plaintext and two encryption keys K1 and K2 a cipher text can be generated as, Cipher Text = E(K2, E(K1, Plaintext)) Encryption in Triple DES: Given a plaintext and two encryption and decryption keys K1, K2 and K3, a cipher text can be generated as Cipher Text = E(K3, D(K2, E(K1, Plaintext))) Task of S-Box: An S-box is a substitution box and it is the only non-linear component in the cipher. Its main purpose is to obscure the relationship between the key, the plaintext, and the ciphertext. The role of the S-boxes is the function F is that the substitution consists of a set of eight S-boxes, each of which accepts 6 bits as input and produces 4 bits as follows: The first and last bits of the input to box Si form a 2-bit binary number to select one of the four substitutions defined by the four rows in the table for Si. The middle four bits select one of the sixteen columns. The decimal value in the cell selected by the row and column is then converted to its 4-bit representation to produce the output. For Example: in S1, for input 011001, the row is 01 and the column is 1100. The value in row 1, column 12 is 9. So, the output is 1001.

Define CIA triad. State the encryption process of double and triple DES. What is the task of S-Box in DES ? Discuss with an example.

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Define CIA triad. State the encryption process of double and triple DES. What is the task of S-Box in DES ? Discuss with an example.

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