James Bowes - Post 16 Computer Science

De Morgan's Law "Either logical function AND or OR may be replaced by each other, given certain changes to the equation." NOT (A OR B) = (NOT A) AND (NOT V) Distribution "Multiplying or factoring of an expression" A AND (B OR C) =  (A AND B) OR (A AND C) Association "Allows for removal of brackets from an expression and regrouping of variables" A OR (B OR C) = (A OR B) OR C = A OR B OR C Commutation "The order of application of two separate values does not matter" A AND B = B AND A Double Negation "If you reverse something twice, you end up back where you started" THE NOT NOT OF A = A. Absorption  "The second term inside the bracket can always be eliminated and 'absorbed' by the term outside the bracket if the given conditions are met" "Rules: Operators outside and inside bracket must be different. The term outside bracket must also be inside the bracket." X OR

Symmetric Encryption - Private Key Symmetric encryption is a type of encryption where only one key (a secret key) is used to both encrypt and decrypt electronic information. The entities communicating via symmetric encryption must exchange the key so that it can be used in the decryption process. Asymmetric Encryption - Public Key One public key, one private key. A public key is used to encrypt which everyone can see and then the private key is unique to each user to unlock.  Digital Signatures Used to verify the data has come from a genuine source and no malicious files are contained. Hashing An algorithm is used to convert data into a numerical file. It can only be done one way so cannot be reverse engineered so data is secured. Once a user enters data the algorithm can be used to perform the same hash on that data and then data can be compared for passwords etc.