Encryption Essay Example | Topics and Well Written Essays - 1500 words

Encryption - Essay Example Chung takes V2 kL mod n1 received from Lilly and operates on it by exponentiation modulo n1 with kC to give V2 kLkC mod n1. He intends to use this as session key ks1C to encrypt his message to a client. Ks1C = V2 kLkC mod n1 = 37(127*234) mod 257 = 133 mod 257 Step 4 Lilly takes V1 kC mod n1 received from Chung and operates on it by exponentiation modulo n1 with kL to give V1 kCkL mod n1. She intends to use this as session key ks1L to attempt to decrypt Chung's message to a client. Ks1L = V1 kCkL mod n1 = 126(234*127) mod 257 = 252 mod 257 (b) If Chung and Lilly had both picked the value V4 for their parts of the key exchange using the method illustrated in part (a), the result would be a session key of 192. Complete Table A4 to show how a session key ks = 192 might be encrypted with the client's public key, and then decrypted by the client on receipt. Table A4 Encryption of the session key Step 1 The value for the session key ks supplied in Question 2 Part (b). ks =192 Step 2 The value for the modulus n2 supplied in Question 2 Part (b) n2 =26 Step 3 The value of the session key ks written as text ks expressed in text = one nine two Step 4 A suitable value for Tait's public key KT KT = 15 Step 5 The session key ks encrypted with Tait's public key KT. { ks} KT = C T: {R}ks, {ks}KT = CNINQNIZSC Step 6 __ A suitable value for Tait's private key KT __ KT =7 Step 7 The result of decrypting the encrypted session key __ using Tait's private key KT {{ks}KT}KT = ONENINETWO Question 3 Complete the following unfinished sections in the main body and appendix of the report printed in the appendix to this companion, and referred to in the 'Background for Questions...Today, the encryption process involves altering and rearranging bits of digital data using a systematic procedure that can be converted into a computer program. Encryption is a commonly used method for providing a certain degree of security in technology-based systems. Simple encryption methods include the substitution of letters for numbers, the rotation of letters in the alphabet or the "scrambling" of voice signals by inverting the sideband frequencies. The more complex methods use sophisticated computer algorithms that rearrange the data bits in digital signals. Data is converted into a series of numbers which are then used as input into calculations. The calculated results become the encrypted data (Case Resource). In 1976 the idea of public key encryption was introduced to the field of cryptography. The idea revolved around the premise of making the encryption and decryption keys different so that the sender and recipient need not know the same keys. The sender and the recipient will both have their own private key and a public key would be known by anyone. Each encryption or decryption process would require at least one public key and one private key (Mycrypto.net 2008). Public key encryption techniques or asymmetric key systems avoid the need to distribute keys in secret. Symmetric key systems are those which allow the decryption process to be derived from the encryption key.