Principles of Information Security Chapter 8

Is the science of encryption; combines cryptography and cryptanalysis. It has a long and multicultural history.

Is the process of making and using codes to secure transmission of information. It is used to secure most aspects of Internet and Web uses that require it, drawing on extensive set of protocols and tools designed for that purpose.

Is the process of obtaining orginal message from encrypted message without knowing algorithms.

Is converting orginial message into a form unreadable by unauthorized individuals. With emergence of technology the need for this in information technology environment is greatly increased. All popular Web browsers use this built-in feature for secure e-commerce applications.

Is the process of converting the ciphertext message back into plaintext.

This can be encrypted through bit stream or block cipher method.

Is when each plaintext bit is transformed into a cipher bit one bit at a time.

Is when the message is divided into blocks (e.g., sets of 8 or 16 bit blocks) and each is transformed into encrypted "Blank" of "Blank" bits using algorithm and key.

Will substitue one value for another.

This uses only one alphabet.

This is more advanced and uses two or more alphabets.

Is an advanced cipher type that uses simple polyalphabetic code; made up of 26 distinct cipher alphabets.

This is easy to understand, but if properly used, produces eiphertext that is difficult to decipher. It rearragnes values within a block to create ciphertext. It can be done at the bit level or at the byte level. To make the encryption even stronger, the keys and block sizes can be made much larger.

Is a funtion of Boolean algebra; two bits are compared. (e.g., if two bits are identical, result is binary 0: if two bits are not identical, result is binary 1) It is a very simple symmetric cipher that is used in many applications where security is not a defined requirement.

This uses a set of characters once per encryption process. This was developed by AT&T.